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Randa Al-Harizy Prof of Internal Medicine Much information may be obtained from the history and physical examination: Is there a generalized haemostatic defect? Bleeding from multiple sites, spontaneous bleeding, and excessive bleeding after injury. Is the defect inherited or acquired? A family history of a bleeding disorder Severe inherited defects usually become apparent in infancy, while mild inherited defects may only come to attention later in life. Some defects are revealed by routine coagulation screens which are performed before surgical procedures. Is the bleeding suggestive of a vascular/platelet defect or a coagulation defect? Vascular/platelet bleeding is characterized by easy bruising and spontaneous bleeding from small vessels. There is often bleeding into the skin. The term purpura includes both petechiae, which are small skin haemorrhages varying from pinpoint size to a few millimetres in diameter and which do not blanch on pressure, and ecchymoses, which are larger areas of bleeding into the skin. Bleeding also occurs from mucous membranes especially the nose and mouth. Coagulation disorders are typically associated with haemarthroses and muscle haematomas, and bleeding after injury or surgery. There is often a short delay between the precipitating event and overt haemorrhage or haematoma formation. Blood count and film show the number and morphology of platelets and any blood disorder such as leukaemia or lymphoma. The normal range for the platelet count is 150-400 × 109/L. Bleeding time measures platelet plug formation in vivo. It is normally between 3 and 10 minutes. Prolonged bleeding times are found in patients with platelet function defects, and there is a progressive prolongation with platelet counts less than 80 × 109/L. The bleeding time should not be performed at low platelet counts. Coagulation tests are performed using blood collected into citrate, which neutralizes calcium ions and prevents clotting. The prothrombin time (PT) is measured by adding tissue thromboplastin in the form of animal brain extract, or a recombinant equivalent, and calcium to the patient's plasma ('extrinsic' system). The normal PT is 16-18 s, and it is prolonged with abnormalities of factors VII, X, V, II or I, liver disease, or if the patient is on warfarin. The activated partial thromboplastin time (APTT) is also sometimes known as the PTT with kaolin (PTTK). It is performed by adding a surface activator (such as kaolin), phospholipid (as platelet substitute) and calcium to the patient's plasma ('intrinsic' system). The normal APTT is 30-50 s depending on the exact methodology, and it is prolonged with deficiencies or inhibitors of one or more of the following factors: XII, XI, IX, VIII, X, V, II or I (but not factor VII) . The thrombin time (TT) is performed by adding thrombin to the patient's plasma. The normal TT is about 12 s, and it is prolonged with fibrinogen deficiency, dysfibrinogenaemia (normal level of fibrinogen but abnormal function) or inhibitors such as heparin or FDPs. Correction tests can be used to differentiate prolonged times in the PT, APTT and TT due to various coagulation factor deficiencies and inhibitors of coagulation. Prolonged PT, APTT or TT because of coagulation factor deficiencies are corrected by addition of normal plasma to the patient's plasma; no correction of an abnormal result after the addition of normal plasma is suggestive of the presence of an inhibitor of coagulation. Factor assays are used to confirm coagulation defects, especially where a single inherited disorder is suspected. Special tests of coagulation will often be required to confirm the precise haemostatic defect. Such tests include estimation of fibrinogen and FDPs, platelet function tests such as platelet aggregation and tests of the fibrinolytic pathway. Results in spontaneous bleedings mostly affecting the skin resulting in purpuric eruptions and ecchymosis and also affecting the mucus membranes with gingival, conjunctival and orificial bleeds. Prolonged bleeding after trauma is also common. Intracerebral and intraabdominal bleedings can also occur. Where platelets are normal in count and function. They include hereditary hemorrhagic telangiectasia. An autosomal dominant trait affecting the mucous membranes and skin resulting in gastrointestinal bleedings and chronic iron deficiency. The causes of vascular bleeding disorders also include: Simple easy bruising: occuring in healthy women Senile purpura: due to atrophy of the supporting tissues of blood vessels and affects the dorsum of the hands and forearms Purpura associated with infections e.g. infective endocarditis Vasculitis: characterized by palpable purpura e.g. Henoch- Schonlein purpura: immune complex reaction with hematuria, abdominal pains and joint affection. Usually self limited though can progress to severe renal involvement. SLE, polyarteritis nodosa Vitamin C deficiency: where the purpuric eruptions are around hair follicles Hereditary connective tissue disorders with abnormal collagen as in Ehlers-Danols syndrome and pseudoxanthoma elasticum A- Quantitative platelet abnormalities -Thrombocytopenia: Quantitative reduction of platelets can results from a defective production from the marrow, an increased consumption or abnormal distribution and rarely from a dilutional effect Failure of platelet production by the bone marrow Selective depression of megakaryocytes as with drugs, chemicals or infections Part of generalized bone marrow failure as in aplastic, dysplastic marrow or with bone marrow infiltration Increased consumption of the platelets: Immune mediated reactions as in autoimmune and idiopathic, drug-induced including heparin, infections and neonatal Consumption as in disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome Hypersplenism Dilutional as in cases of massive transfusion of stored blood Thrombocytopenia is due to immune destruction of platelets. The antibody coated platelets are removed following binding to Fc receptors on macrophages. ITP in children The condition is usually acute but self-limiting and may follow a viral infection or immunization. Bone marrow examination is not usually performed unless treatment becomes necessary on clinical grounds. ITP in adults The presentation is usually less acute than in children. Adult ITP is characteristically seen in women and may be associated with other autoimmune disorders such as SLE, thyroid disease and autoimmune haemolytic anaemia (Evans' syndrome), in patients with chronic lymphocytic leukaemia and solid tumours, and after infections with viruses such as HIV. Platelet autoantibodies are detected in about 60-70% of patients, and are presumed to be present, although not detectable, in the remaining patients; the antibodies often have specificity for platelet membrane glycoproteins IIb/IIIa and/or Ib. Clinical features: Major haemorrhage is rare and is seen only in patients with severe thrombocytopenia. Easy bruising, purpura, epistaxis and menorrhagia are common. Physical examination is normal except for evidence of bleeding. Splenomegaly is rare. Investigation : The only blood count abnormality is thrombocytopenia. Normal or increased numbers of megakaryocytes are found in the bone marrow The detection of platelet autoantibodies is not essential for confirmation of the diagnosis. Treatment: Children do not usually require treatment. Where this is necessary on clinical grounds, high-dose prednisolone is effective, given for a very short course. Intravenous immunoglobulin (i.v. IgG) should be reserved for very serious bleeding or urgent surgery. Adults: Patients with platelet counts greater than 30 × 109/L require no treatment unless they are about to undergo a surgical procedure. First-line therapy consists of oral corticosteroids 1 mg/kg body weight but i.v. IgG is useful where a rapid rise in platelet count is desired, especially before surgery. There are also advocates for high-dose corticosteroids as initial therapy. Second-line therapy involves splenectomy, to which the majority of patients respond, but a wide range of treatments is available in chronic ITP. These include high-dose corticosteroids, high-dose i.v. IgG, intravenous anti-D, vinca alkaloids, danazol, immunosuppressive agents such as azathioprine, ciclosporine and dapsone. There is also interest in the use of specific monoclonal antibodies such as rituximab, as well as recombinant thrombopoietin. Platelet transfusions are reserved for intracranial or other extreme haemorrhage, where emergency splenectomy may be justified. TTP-HUS results from factors leading to platelet aggregation and formation of microvascular thrombi. These factors include toxins, drugs or defeciency of von Willebrand cleaving protease Red cells are sheared leading to microangiopathic hemolytic anemia and the consumption of the platelets leads to a paradox of ischemia of the involved organs and bleeding thrombocytopenia Hemolytic anemia, thrombocytopenia, fever, neurological and renal impairement constitute the syndrome Treatment: Plasma exchange should be initiated promptly and carried out daily till LDH and platelet count are normalized. Steroids, immunosuppression and splenectomy are used in refractory cases May be congenital as Glanzman’s thrombasthenia and von Willibrand’s disease Acquired: as seen with drugs such as aspirin, clopidogrel, NSAIDS, and many antibiotics. They are also seen in myelodysplastic syndrome and renal failure Common causes of abnormal coagulation tests Prolonged PTT Prolonged PT Prolonged PT/PTT LA LA LA Heparin Warfarin Liver disease Deficiency of factor Vitamin K deficiency Warfarin VIII, IX, XI, XII Hypofibrinogenemia Deficiency or Deficiency of factor II, inhibitors to II, VII,X V, X Hypofibrinogenemia DIC Hypofibrinogenemia Congenital coagulation factor deficiencies result in bleeding. Characteristically, the bleeding occurs in response to trauma. Haemarthrosis, muscle hematoma, retroperitoneal and intracranial collections, postoperative bleeding and hematuria are usually the presenting features. Factor VIII deficiency is X-linked, resulting in bleeding with prolonged PTT. Desmopressin (synthetic vasopressin) are used for mild cases. Factor VIII concentrate is needed in severe cases or in the presence of bleeding. In the absence of concentrates, cryoprecipitate can be used, though the risks of viral infections are very high 25% of patients with hemophilia A will develop inhibitors to the transfused factor necessitating the use of excess human factor to bypass the inhibitor or use a prothrombin complex concentrate or more recently recombinant activated factor VIIa Hemophilia B (Christmas disease): It is less common and results from factor IX deficiency von Willebrand disease (vWD): It results from quantitative (type 1 and 3) or qualitative (type 2) deficiency of von Willebrand factor. vWF is an adhesive protein needed for platelet adhesion and aggregation and is also carrier of factor VIII. Subsequently in vWD, PTT is prolonged because of the lack of availability of factor VIII and prolonged bleeding time resulting from platelet dysfunction. Desmopressin and vWF replacement are usually the lines of therapy Congenital deficiencies of factor V, VII and XI are less common Vitamin K deficiency Vitamin K is necessary for the γ-carboxylation of glutamic acid residues on coagulation factors II, VII, IX and X and on proteins C and S. Without it, these factors cannot bind calcium. Deficiency of vitamin K may be due to: inadequate stores, as in haemorrhagic disease of the newborn and severe malnutrition (especially when combined with antibiotic treatment) malabsorption of vitamin K, a fat-soluble vitamin, which occurs in cholestatic jaundice owing to the lack of intraluminal bile salts oral anticoagulant drugs, which are vitamin K antagonists. The PT and APTT are prolonged and there may be bruising, haematuria and gastrointestinal or cerebral bleeding. Minor bleeding is treated with phytomenadione (vitamin K1) 10 mg intravenously. Some correction of the PT is usual within 6 hours but it may not return to normal for 2 days. Liver disease Liver disease may result in a number of defects in haemostasis: Vitamin K deficiency. This occurs owing to intrahepatic or extrahepatic cholestasis. Reduced synthesis. Reduced synthesis of coagulation factors may be the result of severe hepatocellular damage. The use of vitamin K does not improve the results of abnormal coagulation tests, but it is generally given to ensure that a treatable cause of failure of haemostasis has not been missed. Thrombocytopenia. This results from hypersplenism due to splenomegaly associated with portal hypertension or from folic acid deficiency. Functional abnormalities. Functional abnormalities of platelets and fibrinogen are found in many patients with liver failure. Disseminated intravascular coagulation. DIC may occur in acute liver failure. Disseminated intravascular coagulation (DIC) There is widespread generation of fibrin within blood vessels, owing to activation of coagulation by release of procoagulant material, and by diffuse endothelial damage or generalized platelet aggregation. The consequences of these changes are a mixture of initial thrombosis followed by a bleeding tendency due to consumption of coagulation factors and fibrinolytic activation. Causes of DIC These include: malignant disease, septicaemia (e.g. Gram-negative and meningococcal), haemolytic transfusion reactions obstetric causes (e.g. abruptio placentae, amniotic fluid embolism), trauma, burns, surgery, other infections (e.g. falciparum malaria), liver disease or snake bite. Clinical features The underlying disorder is usually obvious. The patient is often acutely ill and shocked. The clinical presentation of DIC varies from no bleeding at all to profound haemostatic failure with widespread haemorrhage. Bleeding may occur from the mouth, nose and venepuncture sites and there may be widespread ecchymoses. Thrombotic events may occur as a result of vessel occlusion by fibrin and platelets. Any organ may be involved, but the skin, brain and kidneys are most often affected. Disseminated intravascular coagulation (DIC) Investigations The diagnosis is often suggested by the underlying condition of the patient. Severe cases with haemorrhage, The PT, APTT and TT are usually very prolonged and the fibrinogen level markedly reduced. High levels of FDPs, including D-dimer are found owing to the intense fibrinolytic activity stimulated by the presence of fibrin in the circulation. There is severe thrombocytopenia. The blood film may show fragmented red blood cells. Treatment The underlying condition is treated and this may be all that is necessary in patients who are not bleeding. Maintenance of blood volume and tissue perfusion is essential. Transfusions of platelet concentrates, FFP, cryoprecipitate and red cell concentrates is indicated in patients who are bleeding. The use of heparin to prevent intravascular coagulation is rarely indicated. Inhibitors of fibrinolysis such as tranexamic acid should not be used in DIC as dangerous fibrin deposition may result. Antithrombin and/or activated protein C concentrates have been used in selected cases.
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