010311 Hemolytic and Megaloblastic Anemia by m1Z60682

VIEWS: 153 PAGES: 11

									                            Year Level 7 [Module #16: Hematology]
                            HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                            Beatriz Gepte, MD, MPH                                                                January 3, 2011

 OUTLINE:                                                                      5.   Increased mechanical fragility due to increased
 I. Introduction                                                                    membrane deformability
      A. The Red Blood Cell
      B. Red Cell Life Span                                          II. HEMOLYTIC ANEMIAS
 II. Hemolytic Anemias                                                       Hemolysis is defined as the premature destruction of
      A. Hereditary Spherocytosis                                             red blood cells (RBCs)
      B. Pyruvate Kinase deficiency                                           o Rate of destruction exceeds the capacity of the
      C. G6PD Deficiency                                                           bone marrow (BM) to produce RBCs
      D. Thalassemia                                                          o RBC survival is shortened
      E. Iron Deficiency Anemia                                               o Erythropoietin is increased  the stimulation of
 III. Megaloblastic Anemia                                                         marrow activity  heightened RBC production
      A. Folic Acid Deficiency                                                      increased percentage of reticulocytes in the
      B. Vitamin B12 Deficiency                                                    blood
 IV. Summary                                                                           Reticulocytes = young RBCs; can be seen in
 Note: Text in italics or with diamond bullets are audio                                peripheral smear, presence of these in
                                                                                        peripheral smear gives the suspicion of
I. INTRODUCTION                                                                         hemolytic anemia with marrow
   A. The Red Blood Cell                                                                compensation – as such, they are measured
         No nucleus                                                                    during hemolytic process in order to see if
          o Better vessel for oxygen transport                                          the BM is compensating.
          o Loss of ability for protein synthesis                             o The marrow can increase its output 2 to 3-fold
          o Finite life span                                                       acutely, with a maximum of 6 to 8-fold in long-
         No mitochondria                                                          standing hemolysis
          o Cannot generate ATP through Kreb’s cycle                                   Even if you hemolyze, you may not develop
          o Metabolism of glucose by anaerobic glycolysis                               anemia for as long as your bone marrow
                (Embden-Meyerhof pathway) and pentose                                   can compensate. However, if this
                phosphate pathway                                                       compensatory mechanism is overwhelmed,
         Importance of ATP                                                             you may have severe anemia.
          1. Maintenance of electrolyte gradients
             o Accomplished by an energy (ATP)-dependent                General Principles
                membrane mechanism, the cation pump                          Reticulocyte Count and Reticulocyte Index
          2. Initiation of energy production                                  o Reticulocyte index = reticulocyte count (in %) *
             o ATP is required for the initial reaction of                          (observed hematocrit/actual hematocrit) * (1/μ)
                glycolysis involving phosphorylation of glucose               o μ = maturation factor of 1-3 related to the
                to glucose-6-phosphate                                              severity of the anemia
          3. Maintenance of RBC membrane and shape                                            Hct       μ
             o Maintains phospholipid structure of the RBC                                    36-45     1
                membrane and the RBC’s biconcave shape                                        26-35     1.5
          4. Maintenance of heme iron in the reduced (ferrous)                                16-25     2
             form                                                                             < 15      2.5
             o Oxidative potentials within the RBC are                        o Normal Reticulocyte Index = 1, hemolysis = 2-3
                inactivated                                                         or more
             o Protection of RBCs from the effects of oxidation               o The higher the anemia, the higher the mu (μ).
                ultimately depends on NADPH and NADH                         General consequences of hemolysis
          5. Maintenance of the levels of organic phosphates                  1. Erythroid hyperplasia resulting to the expansion
             such as 2,3-diphosphoglycerate (2-3 DPG) and ATP                       of the medullary spaces at the expense of the
             within the RBCs                                                        cortical bone
             o Have profound effects on oxygen affinity                             □ For instance, the skull may thicken in order
                                                                                          to make new red blood cells
   B. Red Cell Life Span                                                      2. Increased billiary excretion of heme pigment
         The average life span for a neonatal RBC is 60-90                         derivatives and increased urinary and fecal
                                        rd
          days, approximately ½ to 2/3 that of an adult RBC                         urobilinogen
          (120 days).                                                               □ Patient may have tea-colored urine
          1. A rapid decline in intracellular enzyme activity                 3. Gallstones composed of calcium bilirubinate may
                and ATP                                                             be formed in children as young as 4 yrs of age
          2. Loss of membrane surface area by                                            Usual gallstone formers: Fat, Female, Fourty
                internalization of membrane lipids                                        (3 Fs!)
          3. Decreased levels of intracellular carnitine                      4. Elevations of serum unconjugated bilirubin and
          4. Increased susceptibility of membrane lipids and                        lactic dehydrogenase
                proteins to peroxidation
 Team 7 | Agustin, Aranjuez, Magat, Maglaque, Ocampo, Parco, Regalado, Serrano, Tan, Tanbonliong                         Page 1 of 11
                                                                                 HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                      Year Level 7 [Module #15: Hematology]|January 3, 2011

            Presence of free hemoglobin in the plasma and
           5.                                                             2. Extracellular – resulting from antibodies,
            urine                                                              mechanical factors, or plasma factors
            □ yellowish plasma instead of being straw                o Autoimmune Hemolytic Anemias are usually
                 colored                                                  found in SLE and other Autoimmune Diseases.
       Hemolytic anemia
        o Can be extravascular or intravascular               A. Hereditary spherocytosis
                Intravascular: RBCs do not have to pass            Epidemiology
                 through liver and spleen for them to be             o Prevalence of approximately /5,000 in people of
                 destroyed                                                Northern European descent
                Extravascular: RBC destruction happens in           o Most common inherited abnormality of the red
                 spleen or liver                                          blood cell (RBC) membrane
        o Classification of hemolytic anemias                        o 25% do not have a family history, mostly
            1. Cellular – resulting from intrinsic                        representing a new mutation
                 abnormalities of the membrane, enzymes,             o Unknown epidemiology in the Philippines.
                 or hemoglobin
__________________________________________________________________________________________________________




                                          Figure 1. Pathophysiology of Hereditary Spherocytosis
          Etiology                                                                 Depending on the gene, the surface membrane
Protein        Band     Gene        Proportion        Inheritance                    protein may be either defective or deficient.
               on Gel               of Patients                                     Mostly, dominant in band 3 is involved.
                                    w/ HS                                           Spectrin can be dominant or recessive.
Ankyrin         2.1     ANK1        50-67%            Dominant                      Spectrin and ankirin both are present in the lipid
                                                      and Recessive                  surface membrane of RBCs – deficiency / defective
Band 3          3      AE1          15-20%            Mostly                         causes uncoupling of phospholipid bilayer.
                       (SLC4A1)                       dominant                      Normal RBC has a large surface membrane area so
β Spectrin    2        SPTB         15-20%            Dominant                       as to be easily deformed when passing through
α Spectrin    1        SPTA1        < 5%              Recessive                      blood vessels.
Protein 4.2   4.2      EPB42        < 5%              Recessive                     PBS (peripheral blood smear) will have RBC
            Genes involved are already identified.                                  fragmentation, burr cells, spherocytosis.



Team 7 |                                                                                                                   Page 2 of 11
                                                                             HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                   Year Level 7 [Module #15: Hematology]|January 3, 2011

            Depending on the gene mutation, some affected
              people can be asymptomatic.
            On PE, you can appreciate splenomegaly or
              gallstones.
            On EBV or parvovirus infection, you can get
              aplastic anemia.
            Spherocytes have no central pallor, unusually high
              spherocyte count
          Clinical manifestations
           o Severe anemia and hyperbilirubinemia in the
                 newborn period requiring phototherapy or
                 exchange transfusions
           o Asymptomatic
           o Severe anemia with pallor, jaundice, fatigue, and
                 exercise intolerance
           o Splenomegaly
           o Pigmentary (bilirubin) gallstones may form as                    o
                 early as age 4-5 yrs                                                   Figure 3. Osmotic Fragility Test
           o Susceptible to aplastic crisis
                                                                             Differential diagnosis
                                                                              o Isoimmune hemolytic disease of the newborn
                                                                                       Due to ABO and RH incompatibility
                                                                                       Detection of antibody on an infant’s RBC
                                                                                        using a direct antiglobulin (Coomb’s) test
                                                                              o Autoimmune hemolytic anemias
                                                                                       Evidence of previously normal values for
                                                                                        hemoglobin, hematocrit, and reticulocyte
                                                                                        count
                                                                              o Rare causes of spherocytosis
               Figure 2: Spherocytosis                                                 Thermal injury, clostridial septicaemia with
          Laboratory findings                                                          exotoxemia, and Wilson disease
           o Reticulocytosis                                                 Treatment
           o Indirect hyperbilirubinemia                                      o Splenectomy (Recommended after age 5-6 yrs)
           o Increased MCHC 36-38 g/dL                                                 Curative!
           o Spherocytes usually account for > 15-20% of the                           Indications
               cells when hemolytic anemia is present                                   1. Severe anemia
           o Erythroid hyperplasia is evident in the marrow                             2. Reticulocytosis
               aspirate or biopsy                                                       3. Hypoplastic or aplastic crises
           o Marrow expansion may be evident on routine                                 4. Poor growth
               Xray                                                                     5. Cardiomegaly
           o Gallstones on UTZ                                                o Partial splenectomy also may be useful in
          Diagnosis                                                               children younger than age 5 and can provide
           o The diagnosis of hereditary spherocytosis usually                     some increase in hemoglobin and reduction in
               is established clinically from the blood film,                      the reticulocyte count, with potential
               which shows many spherocytes and                                    maintenance of splenic phagocytic and immune
               reticulocytes, from the family history, and from                    function
               splenomegaly                                                            Younger children undergo partial
           o Osmotic fragility test                                                     splenectomy because they still need their
                    Nonspecific                                                        spleens for immune responses against
                    Normal test result also may be found in 10-                        capular bacteria.
                     20% of patients.                                                  If you have a patient who underwent
                    Procedure: Incubate the patient’s blood at                         splenectomy and yetstill present with
                     specific gradients of NaCl for 24 hours.                           anemia, wrong diagnosis or presence of
                     Positive for HS: get RBC lysis at around 2                         accessory spleens may be the causes.
                     hours.                                                    The spleen has microcapillaries where most of the
           o Cryohemolysis test                                                  spherocytes are destroyed – hence the curative
           o Osmotic gradient ektacytometry                                      function of splenectomy.
           o Eocin-5-maleimide test                                            After splenectomy, revaccinate patients until
           o DNA analysis                                                        (some say) 21 – but others are revaccinated at an
                                                                                 older age due to severe pneumococcal infections.


Team 7 |                                                                                                                   Page 3 of 11
                                                                             HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                   Year Level 7 [Module #15: Hematology]|January 3, 2011

          Supportive care                                                   Lab findings
           1. Folic acid 1mg/day                                              o Polychromatophilia and mild macrocytosis,
           2. Vaccination prior to splenectomy:                                    elevated reticulocyte count
                   Pneumococcus                                              o Spherocytes are uncommon, but few speculated
                   Meningococcus                                                  pyknocytes (dimpled RBCs) are found
                   Haemophilus influenza type b.                             o Normal non-incubated osmotic fragility
           3. Prophylactic oral penicillin V                                  o Diagnosis relies on demonstration of a marked
                   Age < 5 yr, 125 mg twice daily                                 reduction of RBC PK activity or an increase in the
                   Age 5 through adulthood, 250mg twice                           Michaelis-Menten dissociation constant (Km) for
                    daily                                                          its substrate, phosphoenolpyruvate
                                                                             Treatment
  B. Pyruvate Kinase deficiency                                               o Exchange transfusions may be indicated for
                                                                                   hyperbilirubinemia in newborns
                                                                              o Generally rare need for packed RBCs (pRBCs)
                                                                              o Transfusions of packed RBCs are necessary for
                                                                                   severe anemia or for aplastic crises
                                                                              o Splenectomy for patients w/ recurrent and
                                                                                   severe anemia 5-6 years of age (not curative).
                                                                                        Splenectomy is non-curative because RBCs
                                                                                         can lyse even if outside the splenic
                                                                                         microvasculature.

                                                                       C. G6PD Deficiency
                                                                             High detection in Philippines due to inclusion in
           Figure 4. Fragmented RBCs                                          newborn screening: 1 in every 55 detected.
                                                                             Well studied disease (Biotler)
          No tests exist to diagnose this                                   Most important disease in the hexose
          Pyruvate kinase: important for ATP generation                      monophosphate pathway
          Homozygous for an autosomal recessive gene                         o Remember, G6PD is needed to create NADPH,
          2 types: Deficiency of Amount and Deficiency of                         which is then used to reduce glutathione which is
           Function.                                                               an anti-oxidant (needed to remove oxidants from
          PBS shows fragmented RBCs.                                              RBC for it to survive)
          Marked reduction in RBC PK or production of an                    Responsible for 2 clinical syndromes:
           abnormal enzyme w/ decreased activity                              o Episodic, hemolytic anemia induced by
           o Decreased ATP  RBc’s cannot maintain                                 infections, certain drugs, or rarely, fava beans (in
                 potassium and water content  cells become                        Philippines, Dingdong nuts have fava beans!)
                 rigid  life span is considerably reduced                    o Spontaneous chronic nonspherocytic hemolytic
          Etiology                                                                anemia
           o Defect in the human PKLR gene located on                        Affects more than 400 people worldwide
                 chromosome 1q21                                             “Balanced Polymorphism” – evolutionary advantage
           o 133 mutations are reported in this structural                    of resistance to falciparum malaria in heterozygous
                 gene, which codes for a 574-amino acid protein               females that outweighs the small effect of affected
                 that forms a functional tetramer                             hemizygous males
          Clinical manifestations                                           Etiology
           o Severe neonatal hemolytic anemia                                 o X-linked
                      Jaundice and anemia                                    o Inheritance of any of a large number of
                      Kernicterus has been reported                               abnormal alleles of the gene responsible for the
           o Mild, varies in severity, with hemoglobin values                      synthesis of G6PD protein
                 ranging from 8-12 g/dL                                       o Milder disease is associated with mutations near
                      Associated with some pallor, jaundice,                      the amino terminus of the G6PD molecule, and
                       splenomegaly                                                chronic nonspherocytic hemolytic anemia is
                      Well-compensated hemolysis first noted in                   associated with mutations clustered near the
                       adulthood                                                   carboxyl terminus
           o Severe form of the disease found among the
                 Amish of the Midwestern United States




Team 7 |                                                                                                                  Page 4 of 11
                           Year Level 7 [Module #16: Hematology]
                           HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                           Beatriz Gepte, MD, MPH                                                                        January 3, 2011




                                              Figure 5. Inheritance of G6PD Deficiency (Remember this!)
                                                                                                 Vicine and convicine hydrolyzed to divicine
(X)Y – Deficient, symptomatic                                                                     and isouramil producing hydrogen peroxide
(X)(X) – Deficient, Sympomatic                                                                    and other reactive oxygen products
(X)x Carrier                                                                            o The degree of hemolysis varies with the inciting
                                                                                            agent, the amount ingested, and the severity of
           o Women can get G6PD def, (not necessarily X-                                    the enzyme deficiency
                 linked) – healthy father + carrier mother = 25%                       Laboratory findings
                 chance of female carrier OR 25% chance of male                         o Abrupt fall in hemoglobin and hematocrit
                 with G6PD def.                                                         o Tea colored urine  jaundice  anemia
           o Father is deficient + normal mother = child will                           o Hexose Monophosphate Shunt – G6PD is
                 have no manifestations but 50% chance of a                                 important for NADPNADPH, glutathione 
                 carrier child                                                              reduced glutathione (antioxidant), continuous
           o Remember the inheritance!!                                                     generation of H2O2 and free oxygen radicals;
           o In high malaria prevalence countries, there is a                               therefore RBCs are not destroyed
                 high population with G6PD def, most probably                           o Unstained or supravital preparations of RBCs
                 for adaptation to Plasmodium falciparum                                    reveal Heinz bodies (precipitated hemoglobin)
                 endemicity
     1. Episodic or induced hemolytic anemia
           o Considerable variation in the defect is noted
                 among various racial groups.
           o No need for blood transfusion, no anemia, no
                 jaundice - a lot don’t know they have it – but
                 upon exposure to certain drugs (e.g.,
                 cotrimoxazole, anti-malarial drugs) or viruses or
                 fava beans or even spontaneously (e.g.,
                 transfusion-dependent), they manifest anemia
                 symptoms.
           o Example: The enzyme activity of RBCs containing
                 the variant enzyme (G6PD B-) in Americans of
                                                                                      Figure 6. Heinz bodies, polychromatophilic cells
                 European descent is very low, often < 1% of
                 normal.
                     rd                                                                 o Fragmented and polychromatophilic cells (5-
           o A 3 common mutant enzyme with markedly
                                                                                            15%).
                 reduced activity (G6PD Canton) occurs in
                                                                                        o In the Philippines, we usually only do
                 approximately 5% of the Chinese population
                                                                                            confirmatory enzyme activity and newborn
           o More than 100 distinct enzyme variants of G6PD
                                                                                            screening.
                 are associated with a wide spectrum of
                                                                                       Diagnosis
                 hemolytic disease
                                                                                        o Direct measurement of enzyme activity
          Clinical manifestations
                                                                                                 Affected persons: < 10% of normal activity
           o Hemolysis develops 24-48 hours after a patient
                                                                                        o Screening tests
                 has ingested a substance that has oxidant
                                                                                                 Decoloration of methylene blue
                 properties of infection
                                                                                                 Reduction of methemoglobin
                                                                                                 Fluorescence of NADPH (the principle
           o Favism
                                                                                                  behind newborn screening for G6PD)

Team 7 | Agustin, Aranjuez, Magat, Maglaque, Ocampo, Parco, Regalado, Serrano, Tan, Tanbonliong                                  Page 5 of 11
                                                                               HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                    Year Level 7 [Module #15: Hematology]|January 3, 2011

           o    G6PD variants also can be detected by                           o    In α -thalassemia, there are relatively fewer α -
                electrophoretic analysis                                             globin chains and an excess of β and γ -globin
           o DNA analysis  can detect carriers                                      chains
           o In Philippines, only screening is done                                       These excess chains form Bart’s hemoglobin
           o Severe G6PD deficiency: RBCs not necessarily                                  (γ 4) in fetal life and Hb H (β 4) after birth
                destroyed only upon exposure because we only                              Prenatally, a fetus w/ α-thalassemia may
                need 2% of G6PD                                                            become symptomatic because HbF requires
          Treatment                                                                       sufficient α-globin gene production,
           o Prevention of hemolysis constitutes the most                                  whereas postnatally, infants with β-
                important therapeutic measure                                              thalassemia become symptomatic because
           o Supportive therapy may require blood                                          Hb A requires adequate production of β-
                transfusions.                                                              globin genes
           o Vitamin E and Ginkgo Biloba – there are studies                              Babies with α –thalassemia can get hydrops
                being done at the moment.                                                  fetalis.
           o Splenectomy not recommended.
           o Usually asymptomatic, therefore just preventive              1.    Homozygous β -thalassemia (thalassemia Major,
                medicine such as avoidance of inciting agents.                  cooley anemia)
           o Injectable glutathione – no studies to support                     o Severe anemia requiring regular transfusions (6
                that it can prevent hemolysis                                        mos of life)
                                                                                o Classic findings: typical facies (maxillary
    2.     Chronic nonspherocytic hemolytic anemia                                   hyperplasia, flat nasal bridge, frontal bossing),
           o Type of G6PD that requires constant transfusion                         pathologic bone fractures, marked
           o Caused by enzyme variants, particularly those                           hepatosplenomegaly and cachexia.
               defective in quantity, activity or stability
           o Gene defects located primarily in the region of
               the NADP binding site near the carboxyl
               terminus of the protein
           o Impairment of the regeneration of GSH as an
               oxidant “sump”
           o Manifest as pallor, jaundice, splenomegaly
               requiring regular transfusions.
           o Occasionally mistaken as hereditary
               spherocytosis, thalassemia, etc.

  D. Thalassemia
        Epidemiology
         o 3% of the world’s population carries genes for β-
              thalassemia
         o 5-10% of the population carries genes for α-
              thalassemia in Southeast Asia
         o In the US, an estimated 2000 individuals have β-              Figure 7. Skull becomes so thick, hair-on-end appearance
              thalassemia
        Pathophysiology                                                        o    Spleen may become so enlarged that it causes
         o An imbalance in α - and β -globin chain                                   mechanical discomfort and secondary
              production                                                             hypersplenism
         o In bone marrow, thalassemic mutations disrupt                        o    Hemosiderosis
              the maturation of red blood cells, resulting in                   o    Maintain >9 grams iron.
              ineffective erythropoiesis                                        o    Use serum ferritin because liver biopsy can’t be
         o In β -thalassemias, there is an excess of α -globin                       done always – although liver biopsy is the MOST
              chains relative to β or γ -globin chains – you also                    accurate.
              get anemia.                                                       o    Serum ferritin is an acute phase reactant – easily
                  α -globin tetramers (α 4) are formed, and                         increased in times of infection; therefore, make
                   these inclusions interact with the red cell                       sure that inflammation is not present during test.
                   membrane and shorten red cell survival                       o    Laboratory findings
                  The γ -globin chains are produced in                                  HbF (α2γ2) can be seen in Hb
                   increased amounts, leading to an elevated                              electrophoresis
                   Hb F (α2γ2)                                                           Thalassemia minor: only needs transfusion
                  The δ -globin chains are also produced in                              during crisis
                   increased amounts, leading to an elevated                             Severe hypochromic anemia
                   Hb A2(α2 δ 2) in β -thalassemia                                       Numerous nucleated red cells
                                                                                         Microcytosis with target cells.

Team 7 |                                                                                                                    Page 6 of 11
                                                                                  HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                        Year Level 7 [Module #15: Hematology]|January 3, 2011

           o    Treatment                                                                   Transfusion is not commonly used for
                    Blood transfusion                                                       therapy because the range of hemoglobin is
                      Promotes general health and well-                                     7.0–11.0 g/dL, with a mean corpuscular
                         being and avoids the consequences of                                volume of 51–73 fl.
                         ineffective erythropoiesis                                d. Deletion of all 4 a-globin genes
                    Chelation                                                              Causes profound anemia during fetal life,
                      Counteracts iron deposition                                           resulting in hydrops fetalis
                      Measurement of the iron level by liver                                 There are no normal hemoglobins
                         biopsy is the standard method for                                        present at birth (primarily Bart’s
                         accurately determining the iron store -                                  hemoglobin, with Gower-1, Gower-2
                         but in practice, serum ferritin is                                       and Portland)
                         measured instead                                                     If the fetus survives, immediate
                    Bone marrow transplantation has cured >                                      exchange transfusion is indicated.
                     1,000 patients who have thalassemia major                                Infants with α- thalassemia major are
                      Most success has been in children                                          transfusion-dependent, and bone
                         younger than 15 years of age without                                     marrow transplant is the only cure.
                         excessive iron stores and without                         e. Hb H Constant Spring
                         hepatomegaly, who have HLA-matched                                 Nondeletional a-globin mutation with a 2-
                         siblings                                                            gene deletion (-a/a, aCS)
                      Splenectomy is not curative – rather, it                             Results in more severe anemia than
                         only decreases transfusion requirement                              deletion type of α-globin thalassemia
                         – spleen is needed for deposition of                               Increased hepatosplenomegaly, increased
                         iron, so if the spleen is absent, it will                           jaundice, and a much more severe clinical
                         deposit in other organs – like the lungs.                           course.
                      But in Philippines, splenectomy is done                              Transfusion dependent.
                         (especially if the child is of older age) to             Generally alpha or beta thalassemia, management is
                         reduce transfusion dependence;                            transfusion and chelation; splenectomy to reduce
                         HOWEVER it does not cure thalassemia                      transfusion requirement and comfort
                         - This is done to prevent enlargement
                         of spleen, since enlarged spleen traps             E. Iron Deficiency Anemia (IDA)
                         more RBCs                                                 General facts
                                                                                    o Most common hematologic disease of infancy
    2.     α -thalassemia                                                                and childhood
           a. Deletion of 1 a-globin gene (silent trait)                            o About 1 mg of iron must be absorbed each day
                    No alterations are noted in the mean                                to maintain positive iron balance in childhood
                     corpuscular volume and mean corpuscular                             required for growth and to replace losses (1 mg).
                     hemoglobin                                                     o A diet containing 8-10 mg of iron daily is
                    Individuals with this deletion are usually                          necessary for optimal nutrition since absorption
                     diagnosed after the birth of a child with a 2-                      of dietary iron is assumed to be about 10%
                     gene deletion, or Hb H (β4)                                    o Site of absorption: proximal small intestine
                    Newborn period: <3% Bart's hemoglobin is                       o Iron is absorbed 2-3 times more efficiently from
                     observed                                                            human milk than from cow’s milk
                    Common in African-Americans.                                   o Obese toddlers can also have deficiency of iron if
           b. Deletion of 2 a-globin genes/a-thalassemia trait                           they consume more than 24 oz of milk daily since
                    Presents as a microcytic anemia                                     calcium binds with iron and can’t be absorbed.
                    hemoglobin analysis is normal, except                          o Adolescents are also susceptible to iron
                     during the newborn period, when Bart's                              deficiency
                     hemoglobin is commonly <8%, but >3%                                     High requirements due to the growth spurt
                    distinguished from IDA by history and trial                             Dietary deficiencies
                     tx of iron                                                              Menstrual blood loss
           c. Deletion of 3 a-globin genes: called Hb H disease                    Etiology
                    HbH disease causes patients to be easily                       o Insufficient iron stores during infancy due to
                     fatigued – they are given pRBCs. During the                         prematurity or perinatal hemorrhage
                     newborn period, the Bart’s hemoglobin                          o Inadequate dietary iron is the cause among term
                     level is commonly >25% (Bart’s Hb present                           infants (unusual before 6 mo and usually occurs
                     at birth).                                                          at 9-24 mo of age)
                    At least 1 parent must have a-thalassemia                      o Prolonged consumption of large amounts of
                     trait                                                               cow’s milk (>24 oz/day) and of foods not
                    Definitive diagnosis of Hb H disease                                supplemented with iron
                     requires DNA analysis                                          o Intense physical activity


Team 7 |                                                                                                                     Page 7 of 11
                                                                                 HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                      Year Level 7 [Module #15: Hematology]|January 3, 2011

          Other causes of IDA                                                  Differential diagnosis
           o Chronic blood loss                                                       Ferritin Iron          TIBC       %sat       FEP
                     GIT (milk protein–induced inflammatory           IDA            low        Low         high       low        high
                      colitis, peptic ulcer, Meckel’s diverticulum,    Thalassemia Normal Normal normal normal normal
                      polyp, or hemangioma, inflammatory bowel                        or Inc     or Inc
                      disease, hookworm infestation,                   ACD            Normal low             low        normal
                      Helicobacter pylori)                                            or Inc
                     Pulmonary hemosiderosis – iron                   Lead                                                        high
                      concentrated in pulmonary system.                poisoning
           o Chronic diarrhea                                                             ACD – Anemia of Chronic disease: Iron is
           o Cow’s milk-induced colitis                                                    low because it is sequestered by
                     Due to a protein-losing enteropathy                                  macrophages.
                     Presents with edema and anemia                                      IDA – Iron Deficiency Anemia.
          Clinical manifestations and laboratory findings                                Basically, low ferritin in IDA with high TIBC
           o Pallor                                                                        (total iron binding capacity); high FEP in IDA
           o Pagophagia – eating of clay, soil, etc (pica)                                 and lead poisoning.
           o Plumbism                                                            o TfR is high in IDA and normal in ACD
           o Weight problems                                                     o FEP – free or non-complexed non-heme
           o Irritability                                                             protophorphyrin
           o Anorexia                                                           Treatment
           o Neurologic and intellectual dysfunction                             o Iron therapy: 4-6 mg/kg of elemental iron in 3
           o Low serum ferritin                                                       divided doses
           o Low serum iron level                                                o Proper education in nutrition
           o Increased iron-binding capacity of the serum                        o Time after iron administration and responses
                 (serum transferrin)                                                      12-24 hrs: replacement of intracellular iron
           o Low percent saturation (transferrin saturation-                               enymes, subjective improvement,
                 %sat)                                                                     decreased irritability, increased appetite
           o Accumulation of free erythrocyte                                             36-48 hrs: initial bone marrow response;
                 protoporphyrins (FEP).                                                    erythroid hyperplasia
           o In some cases, patients can have low reticulocyte                            48-72 hrs: Reticulocytosis, peaking at 5-7
                 count in PBS.                                                             days
                                                                                          4-30 days: increase in hemoglobin level 1-2
                                                                                           g/L
                                                                                          1-3 mos: repletion of stores
                                                                                 o Blood transfusion if necessary
                                                                                 o IV iron therapy if oral form cannot be tolerated
                                                                                 o Correction of underlying condition

                                                                       III. MEGALOBLASTIC ANEMIAS
                                                                               rare
                                                                            General Characteristics



               Figure 8. Microcytic hypochromic RBCs of IDA

          Laboratory findings
           o Microcytic, hypochromic RBCs with poikilocytosis
               (increase in abnormal red blood cells of any
               shape where they make up 10% or more of the
               total population)
           o Normal or moderately elevated reticulocyte
               percentage but low absolute reticulocyte counts
               indicate an insufficient response to anemia                                    Figure 9. Megaloblastic anemia
           o Thrombocytosis                                                      Vitamin B12 or Folic acid deficiencies result in
           o Red cell hyperplasia in the bone marrow                              defective synthesis of DNA and, to a lesser extent,
           o No stainable iron in marrow reticulum cells                          RNA and protein
                                                                                 Ineffective erythropoiesis
                                                                                  o RBCs are larger than normal at every stage of
                                                                                       development and have an open, finely dispersed

Team 7 |                                                                                                                    Page 8 of 11
                                                                               HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                     Year Level 7 [Module #15: Hematology]|January 3, 2011

                nuclear chromatin and an asynchrony between                             Malabsorption due to chronic diarrheal
                the maturation of nucleus and cytoplasm, with                            states or diffuse inflammatory disease such
                the delay in nuclear progression becoming more                           as celiac disease or chronic infectious
                evident with further cell divisions Folic acid                           enteritis, and in association with
                deficiency                                                               enteroenteric fistulas
          RBCs are large (increased mean corpuscular volume                             1. May be caused by impaired folate
           [MCV]) and often oval                                                         conjugase activity.
          Giant metamyelocytes and bands also are present in                            2. Interferes with the enterohepatic
           the marrow                                                                    circulation of folate, thereby enhancing
          Hypersegmented neutrophils also are characteristic,                           folate losses because of rapid intestinal
           with many neutrophils having >5 lobes.                                        passage
          The difference with Iron Deficiency Anemia is that                           Previous intestinal surgery
           there are macrocytes and hypersegmented                                      Anticonvulsant drugs (e.g., phenytoin,
           neutrophils.                                                                  primidone, phenobarbital) can impair
                                                                                         absorption of folic acid
                                                                                o Congenital abnormalities in folate metabolism
  A. Folic Acid Deficiency                                                              a very rare disorder that is due to an
         Folic acid is heat-labile and water soluble                                    inability to form biologically active
         Folic acid is absorbed throughout the small intestine                          tetrahydrofolate
          o Folate conjugase activity in the intestinal brush                           severe megaloblastic anemia in early
                border aids the conversion of polyglutamates to                          infancy
                the monoglutamate and thereby enhances                                  treated successfully with large doses of folic
                absorption                                                               acid or folinic acid
         Not biologically active                                                       Deficiency of methylene tetrahydrofolate
          o It is reduced by dihydrofolate reductase to                                  reductase has been described in some
                tetrahydrofolate, which is transported into tissue                       patients with homocystinuria without
                cells and polyglutamated.                                                hematologic abnormalities.
         Megaloblastic anemia occurs after 2–3 mos on a                        o Drug-induced abnormalities in folate metabolism
          folate-free diet                                                              Methotrexate - binds to dihydrofolate
         Vegetarians get this.                                                          reductase and prevents formation of
                                                                                         tetrahydrofolate, the active form
         Patients can develop thrombocytopenia
                                                                                        Pyrimethamine -used in the therapy of
         Clinical manifestations
                                                                                         toxoplasmosis
          o Anemia
                                                                                        Trimethoprim- present in cotrimoxazole
          o Irritability
                                                                                        Therapy with folinic acid (5
          o Inadequate weight gain
                                                                                         formyltetrahydrofolate) usually is
          o Chronic diarrhea
                                                                                         beneficial.
          o Hemorrhages from thrombocytopenia in
                                                                               Laboratory Findings
                advanced cases
                                                                                o Anemia is macrocytic (mean corpuscular volume
          o Peak incidence: 4 – 7 months of life
                                                                                    >100 fL)
          o Very-low-birth weight infants
                                                                                o reticulocyte count is low, and nucleated RBCs
          o May accompany kwashiorkor, marasmus, or
                                                                                    demonstrating megaloblastic morphology
                sprue
                                                                                o Neutropenia and thrombocytopenia may be
         Etiology
                                                                                    present in patients with long-standing and
          o Inadequate folate intake
                                                                                    severe deficiencies
                     Decreased folate intake usually becomes
                                                                                o Neutrophils are large, some with
                      manifest under clinical conditions that have
                                                                                    hypersegmented nuclei
                      increased vitamin requirements e.g.,
                                                                                o Serum folic acid levels are <3 ng/mL(N: 5–20
                      pregnancy, growth in infancy, chronic
                                                                                    ng/mL)
                      hemolysis
                                                                                o Levels of iron and vitamin B12in serum usually
                     Weight-based requirements are higher in
                                                                                    are normal or elevated
                      children than adults because of children's
                                                                                o Serum activity of lactate dehydrogenase (LDH), a
                      increased needs for growth
                                                                                    marker of ineffective erythropoiesis, is markedly
                     Goat's milk is deficient in folic acid
                                                                                    elevated
                     Folate supplementation of at least
                                                                                o Bone marrow findings:
                      400μg/day is recommended from the start
                                                                                        hypercellular because of erythroid
                      of pregnancy to prevent neural tube defects
                                                                                         hyperplasia, and megaloblastic changes
                      and to meet growth needs of the
                                                                                        large, abnormal neutrophilic forms (giant
                      developing fetus
                                                                                         metamyelocytes) with cytoplasmic
          o Decreased folate absorption
                                                                                         vacuolation


Team 7 |                                                                                                                  Page 9 of 11
                                                                              HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                      Year Level 7 [Module #15: Hematology]|January 3, 2011

          Treatment                                                                    Symptoms at around 1 yr of age
           o When the diagnosis of folate deficiency is                                 Weakness, irritability, anorexia, listlessness,
                established, folic acid may be administered                              tongue is smooth, red, and painful,
                orally or parenterally at 0.5–1.0 mg/day.                                neurologic manifestations include ataxia,
           o If the specific diagnosis is in doubt, smaller doses                        paresthesias, hyporeflexia, Babinski
                of folate (0.1 mg/day) may be used for 1 week as                         responses, and clonus
                a diagnostic test, because a hematologic                        o   Lack of Intrinsic Factor - Juvenile pernicious
                response can be expected within 72 hrs.                             anemia
           o Vitamin B12deficiency but may aggravate any                                Atrophy of the gastric mucosa,
                associated neurologic abnormalities                                      achlorhydria, and antibodies in serum
           o Transfusions are indicated only when the anemia                             against IF and parietal cells
                is severe or the child is very ill.                                     Additional immunologic abnormalities,
           o Folic acid therapy (0.5–1.0 mg/day) should be                               cutaneous candidiasis, hypoparathyroidism,
                continued for 3–4 wk until a definite                                    and other endocrine deficiencies
                hematologic response has occurred.                                      Parenteral vitamin B12 should be
           o     Maintenance therapy with a multivitamin                                 administered regularly to these patients
                (containing 0.2 mg of folate) is adequate.                              Gastric surgery can lead to intrinsic factor
                                                                                         deficiency, and susceptible individuals need
  B. Vitamin B12 Deficiency                                                              lifelong parenteral vitamin
        Vitamin B12is derived from cobalamin in food (mainly                            B12supplementation.
         animal sources) secondary to production by                             o   Impaired Vitamin B12 Absorption
         microorganisms                                                                 Regional enteritis or neonatal necrotizing
        Absorbed in the distal ileum via specific receptors for                         enterocolitis
         IF-cobalamin (IF – intrinsic factor)                                           Surgical removal of the terminal ileum
        In the plasma, cobalamin binds to a transport protein,                         Overgrowth of intestinal bacteria within
         transcobalamin II (TC-II), which carries vitamin B12 to                         diverticula or duplications of the small
         the liver, bone marrow, and other tissue storage sites.                         intestine by consumption of (or competition
        TC-II enters cells by receptor-mediated endocytosis,                            for) the vitamin or by splitting of its
         and cobalamin is converted to active forms                                      complex with IF.
         (methylcobalamin and adenosylcobalamin) important                              Fish tapeworm Diphyllobothrium latum
         in the transfer of methyl groups and DNA synthesis.                             infestation of the upper small intestine
        TC I and TC III – no role in transport but reflects body                       Lifelong parenteral administration should
         stores                                                                          be used if there is evidence that vitamin
        In contrast to folate stores, older children and adults                         B12 is not absorbed.
         have sufficient vitamin B12 stores to last 3–5 yrs.                    o   Impaired Vitamin B12 absorption - Imerslund-
        In young infants born to mothers with low vitamin                          Grasbeck syndrome
         B12 stores, clinical signs of cobalamin deficiency can                         Defects of the receptor for IF-B12in the
         become apparent in the first 6–18 months of life.                               terminal ileum
        Etiology                                                                       Autosomal recessive disorder is caused by
         o Inadequate Vitamin B12 Intake.                                                defects in the CUBN gene on chromosome
                   May occur in cases of extreme dietary                                10p12.1, resulting in decreased expression
                    restriction (e.g., strict vegetarians or                             of the IF-B12 receptor cubilin
                    vegans) in which no animal products are                             Parenteral treatment with vitamin B12
                    consumed.                                                            monthly corrects the deficiency
                   Not common in kwashiorkor or infantile                      o   Absence of Vitamin B12 Transport Protein
                    marasmus                                                            Rare congenital deficiency inherited as an
                   Occurs in breast-fed infants whose mothers                           autosomal recessive condition, with failure
                    are vegans or who, themselves, have                                  to absorb and transport vitamin B12
                    pernicious anemia.                                                  Patients lack TC-II, but some have
                   Maternal pernicious anemia may be                                    functionally defective forms
                    manifest by reduced serum vitamin B12with                           Serum vitamin B12 levels are normal
                    or without macrocytic anemia in the                                  because the storage forms of cobalamin,
                    mother. This cause of childhood                                      TC-I and TC-III, are not affected
                    megaloblastic anemia can appear in the first                        Usually manifests in the first weeks of life as
                    year of life.                                                        failure to thrive, diarrhea, vomiting,
         o Lack of Intrinsic Factor - Congenital pernicious                              glossitis, neurologic abnormalities, and
               anemia                                                                    megaloblastic anemia
                   Rare autosomal recessive disorder due to                            diagnosis of this disorder is suggested by
                    an inability to secrete gastric IF or secretion                      the presence of severe megaloblastic
                    of functionally abnormal IF                                          anemia with normal serum vitamin B12 and


Team 7 |                                                                                                                 Page 10 of 11
                                                                                 HEMOLYTIC AND MEGALOBLASTIC ANEMIAS
                                                                    Year Level 7 [Module #15: Hematology]|January 3, 2011

                    folate levels and no evidence of any other                            physiologic requirement 1–5μg/day
                    inborn errors of metabolism                                           if with evidence of neurologic involvement,
                   Tx: large parenteral doses of vitamin B12                              1 mg should be injected intramuscularly
                    given twice a week for life                                            daily for at least 2 wk
                   Most children with this disorder die if                               maintenance therapy is necessary
                    treatment is not provided in infancy.                                  throughout a patient's life: monthly IM of 1
          Laboratory Tests                                                                mg of vit B12
           o Schilling test
                   To confirm that absence of IF is the basis of      IV.       SUMMARY
                    the vitamin B12 malabsorption, IF is given                   History: know when anemia developed, or if it is
                    with a second dose of radioactive vitamin                     congenital.
                    B12. Normal amounts of radioactive vitamin                   Physical Examination: jaundice, icterus,
                    should now be absorbed and flushed out in                     hepatosplenomegaly.
                    the urine.                                                   Differential Diagnoses
                   If vitamin B12 malabsorption results from                    Laboratory Findings
                    absence of ileal receptor sites or other                      o Smears – different RBC anomalies, color of
                    intestinal causes, no improvement in                               plasma, tea-colored urine, hemoglobinuria.
                    absorption occurs with IF.                                   Diagnosis
                   The Schilling test result remains abnormal                    o Stainable iron in bone marrow – gold standard
                    in patients with pernicious anemia, even                           for IDA.
                    when therapy has completely reversed the
                                                                                 Treatment and Outcome
                    hematologic and neurologic manifestations
                                                                                  o Green leafy veggies are good sources of non-
                    of the disease.
                                                                                       Heme iron.
                   It is the test for etiology of Vitamin B12
                                                                                  o Oral or IV Chelation – thalassemia patients need
                    deficiency.
                                                                                       this.
          Treatment
           o Parenteral administration of vit B12 (1 mg)
                   reticulocytosis in 2–4 days, unless there is
                    concurrent inflammatory disease                                                  End




Team 7 |                                                                                                                  Page 11 of 11

								
To top