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BLOOD TESTS AND THEIR MEANINGS

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BLOOD TESTS AND THEIR MEANINGS Powered By Docstoc
					Interpreting Blood Tests and
        Investigations
         Maureen Cox




       RCN Conference January 2009
AIM

 To explore the role of the nurse in
 assisting, carrying out and assessing the
 results of blood tests and investigations
 To discuss the most commonly used
 investigations in the diagnosis of
 rheumatological conditions
 To explore the investigations commonly
 used for the ongoing monitoring of
 therapies used in the treatment of
 rheumatological conditions
 To look at normal values ( and ranges) and
 begin to recognise the significance of the
 results

             RCN Conference January 2009
The Nurses Role in Blood Tests and
Investigations
To provide safe, informed care.
To request investigations that are timely and
appropriate
Support the patient
Provide explanation of need for tests
Carry them out safely for both patient and nurse
Correct labelling and transportation
Interpretation of results
Action taken on abnormal values
Explain results to patient and how this will
influence treatment.
                RCN Conference January 2009
Diagnosis- Commonly used blood tests


Full blood count                   Uric acid
Urea and electrolytes              Creatinine Kinase
Liver function tests               Antinuclear antibodies
                                   Compliment levels
ESR
Plasma Viscosity
C-Reactive Protein
Rheumatoid factor
Anti CCP
                RCN Conference January 2009
           FULL BLOOD COUNT
This is used to monitor disease activity, to assess
the effects of drug treatment, to exclude dietary
deficiency.
IMPORTANT VALUES MEASURED
  Haemoglobin (Hb)
  White cell count (WCC or WBC)
  Neutrophils/Granulocytes
  Eosinophils
  Platelets
  Mean cell volume (MCV)
                 RCN Conference January 2009
               HAEMOGLOBIN (Hb)
Normal value
Male                 13 -18 g dL-1
Female               11.5-15.5 g dL-1

  Low haemoglobin, can be due to the increased
  disease activity.

   A sudden fall in Hb should be checked as this can
indicate blood loss, e.g from anti-inflammatory drugs.
Check FOB’s (Faeces for occult blood)


  Low HB ? Poor Nutrition. Assess function / mobility
                   RCN Conference January 2009
           WHITE CELL COUNT
Normal value     4-11x109/l
These are the cells which “gobble” up infection

A raised white cell count is suggestive of
infection.
White cell count also is elevated when patients
are on or have had steroids.

A low white cell count (below 3.5) can occur
as a side effect to drug treatments.
Patients with SLE and Felty’s often have a low
white cell countRCN Conference January 2009
       NEUTROPHILS (Neuts /Grans)
Specific type of white cell.
Normal value 2 - 7.5 x 109/l (absolute value)
Same as WCC, up with infection,steroids, also
inflammation
Down (below 2) side effect of drug treatment,
SLE flare, viral infections, severe bacterial
infection
   1 - 1.5 no significant risk
   0.5 - 1 some increased risk
   < 0.5 major risk of infection
Also lower in some races - black Africans -”Negro
neutropaenia”       RCN Conference January 2009
                 Eosinophils (EOS)
Another specific type of white cell.
Normal value up to 0.4 (absolute value)
Elevation may indicate:
   Allergy to either a drug i.e Methotrexate
   pneumonitis or asthma.
   Particularly important with Myocrisin (Gold
Injection) as may herald allergic reaction.
   Seen in certain conditions
   – Churg Struass syndrome
   – worm infestations.

                    RCN Conference January 2009
                     PLATELETS
Normal value 150 - 400x109/l

These are the cells which help the blood to clot

Platelets often elevated in active disease
  (thrombocytosis) due to inflammation.

A low platelet count ( thrombocytopaenia) can
  occur
  –   as a side effect of drug treatment,
  –   in patients with active SLE, Felty’s
  –   viral infections
                    RCN Conference January 2009
          MEAN CELL VOLUME (MCV)
Normal value 78 - 104
Reduced MCV(<78) can indicate:
  – Anaemia of chronic disease
  – Iron deficiency anaemia
  (? Need to check Ferritin levels)


Elevated MCV (>104) can indicate:
  –   Vitamin B12 deficiency
  –   Folate deficiency
  –   Thyroid problems
  –   Liver problems
  –   Marrow dysplasia /Aplastic anaemia
                    RCN Conference January 2009
                    FERRITIN
Serum ferritin is an acute phase protein.
It goes up with inflammation.

Ferritin is used as a test to check for iron deficiency
anaemia in patients with a low Hb and low MCV.
In active disease a Ferritin below 90 can indicate
iron deficiency.

If patients are treated with iron supplements they
need to take for at least 3 months then have Ferritin
rechecked before stopping treatment
                    RCN Conference January 2009
           B12 and Folate
Should be measured in patients with
macrocytosis ie elevated MCV

Macrocytosis seen with some DMARD’s
especially Azathioprine, Sulphasalazine and
Methotrexate

May also herald aplastic anaemia – so don’t
ignore!!


             RCN Conference January 2009
      UREA AND ELECTROLYTES

Blood biochemistry is used to check for
abnormalities in the body chemistry.

Abnormal renal or liver function may
occur as a result of organ involvement in
multisystem inflammatory diseases, or a
side effect of drug treatment.


               RCN Conference January 2009
         LIVER FUNCTION TESTS

ALT – Alanine Transaminase (15-45)
 Elevated as a side effect of some drugs
 Alcohol
 Hepatitis and liver damage

Alkaline Phosphatase (up to 300)
  Elevated when bony activity, flare, fractures
  Also as side effect of drugs
  Malignancy

                 RCN Conference January 2009
      Inflammatory Markers
Commonly used to assess disease activity
in RA
– Erythrocyte sedimentation rate (ESR)
– Plasma viscosity ( PV)

– C reactive protein (CRP)




               RCN Conference January 2009
  Erythrocyte Sedimentation Rate (ESR)
 Erythrocyte sedimentation rate measures the rate
at which the red cells settle. The higher the value
the more inflammation. Therefore elevated in active
arthritic disorders such as Rheumatoid Arthritis,
  Lupus, vasculitis, polymyalgia rheumatica
  Also malignancies.

NORMAL VALUES
 0-10mm/hr in men aged 18-65 years
 1-20mm/hr in women aged 18-65 years
 Over 65 can go up by 5-10mm/hr
                 RCN Conference January 2009
         Plasma Viscosity
Used in some hospitals in preference to
ESR
Reacts in the same way as ESR –
elevated with disease activity due to an
increase in protein concentration.
In same way as ESR elevated in
malignancy and paraproteinuraemias
Normal range 1.5 - 1.72cp

            RCN Conference January 2009
            C REACTIVE PROTEIN
An acute phase protein

This is a sensitive and quantitative measurement
used for evaluating severity and course of an
inflammatory process

Considered more accurate than ESR by some.

Normal range 0-8mg/l
NB Oral contraceptives may affect CRP levels
                  RCN Conference January 2009
          RHEUMATOID FACTOR
This test measures the presence of rheumatoid
factor - the circulating immunoglobulin IgM / IgG
It is not a specific test
     Rheumatoid factor is positive in 4-6% of population
    Can be negative - Sero- negative inflammatory
    disease ( AS, PSA)

   Present in 70% of patients with RA
Highest titres found in patients with severe
disease
   It can also be found in patients with cirrhosis,
TB, infection and cancer

                    RCN Conference January 2009
         RHEUMATOID FACTOR 2
Three tests:
  RA latex fixation test >1:40 or higher is
  significant
  Rose-Waaler – Positive at titre of 1:32 or more
  Particle agglutination test – Normal range 0-40

In all tests, antibodies cause agglutination of sheep
red cells, bacteria or latex, which has been coated
with IgG fraction


                  RCN Conference January 2009
RCN Conference January 2009
                    Anti CCP
  Anti Cyclic Citrullinated Peptide Antibody
  Used in diagnosis of RA
  Used as an indicator of potential severity of
  disease

Normal Levels:
< 11 negative
> 11 Positive, the higher the positivity the greater the
  potential for errosive disease

                   RCN Conference January 2009
           SERUM URIC ACID
Uric acid produced as a by-product of purine
  metabolism.
This is the test used if gout is suspected.
Normal value       Male – 210-480 umol/l
                Female – 170-420 umol/l

NB Women do not get gout prior to the
menopause.
Commonly seen in diuretic use.
Men.
               RCN Conference January 2009
                    URIC ACID
In addition to this test,
aspiration of a swollen
joint and the fluid
looked at for uric acid
crystals under the
microscope can
confirm Gout.


                  RCN Conference January 2009
MUSCLE ENZYMES - Creatine Kinase
            (CK)
This is an enzyme released when muscle is
damaged. Often done in post MI to measure for
heart muscle damage.
It is a useful test for muscle disorders such as
Myositis (inflammation of the muscles)

In Myositis the CK level is often elevated into
the 1000’s
(Normal 24-190)
                RCN Conference January 2009
     ANTINUCLEAR ANTIBODIES
Antinuclear antibodies are found in several
rheumatic diseases. It is a useful screening test
  for SLE, most patients with SLE
have +ve ANA, but it is also found in RA,
scleroderma, juvenile arthritis and mixed
connective tissue diseases.

This is a sensitive, but not specific test.
Low titres can be found in 1 - 5% of healthy
population, titres rise with age.
                RCN Conference January 2009
    ANTINUCLEAR ANTIBODIES 2
The test measures and differentiates
antinuclear antibodies.

The immunoglobulins IgM, IgG and
IgA are the antibodies which react with
the nuclear part of leucocytes forming
antibodies to DNA and RNA.

Test uses immunoflorescence to detect
their presence
              RCN Conference January 2009
ANTINUCLEAR ANTIBODIES 3




       RCN Conference January 2009
       Complement – C3 and C4
Useful to diagnose immune complex disease.
The complement system activated by IgM and IgG
and concerned with the mediation of inflammation.
Once system has been activated C3 and C4 act
as enzymes.
Elevate C3 and normal C4 indicates an acute
phase response
Raised or normal C4 occurs in RA
Low C3 and /or C4 suggests SLE, RA or a CTD
Normal values C3 - 0.63- 1.7g/l, C4 - 0.11- 0.45g/l

                RCN Conference January 2009
                TPMT Assay
1:33 individuals lack thiopurine s-methyltransferase
(TPMT) which helps the body remove drugs such as
azathioprine form the body when they are present above
therapeutic levels.
Assessment of TPMT helps to determine if a patient is
going suffer from adverse reactions for Thiopurine drugs
such as Azathioprine

Individuals with no TPMT enzyme can become severely ill
with normal doses of thiopurine drugs because toxic levels
of the drug accumulate, leading to bone marrow
suppression, a reduction in blood cell production, with
subsequent increase in risk of infection and abnormal
bleeding

                   RCN Conference January 2009
        Ongoing Monitoring of
      rheumatological conditions
Clear evidence from randomised placebo
controlled trials that DMARD’s:
–    Reduce symptoms
–   Improve function
–   Improve global well being
–   Improve function
–   Improve long term outcome and survival
Mode of action poorly understood
All have the potential to cause adverse effects
– Require safety monitoring

                   RCN Conference January 2009
     Monitoring of DMARD’s
All DMARD’s present some risk to the
patient, and require regular monitoring to:
– Monitor disease activity
– Monitor the patients general health
– Detect any adverse effects occurring as a result
  of the medication
Patients are cautioned that medication will
not be prescribed if blood monitoring is not
undertaken.

               RCN Conference January 2009
  Current Monitoring Regimes
Revised Guidelines Published by BSR 2008
BSR Website www.rheumatology.org

At commencement of medication
– FBC, U& E’s, LFT’s and CPR every 2 weeks for 3 months then
  monthly
– After 6 months, if stable rheumatologist will advise 6 weekly testing.
  With the exception of Sulphasalazine which can be every 3 months.
If a second DMARD is prescribed in addition to an
established medication, monitoring should revert to 2
weekly for 3 months, and continue monthly


                      RCN Conference January 2009
             Methotrexate
Dose 7.5 mg –25mg WEEKLY(2.5 mg tabs)
If oral dose is not effective or causes intolerance
consider subcutaneous
Folic acid (5mg weekly)to be taken day after
methotrexate
Monthly monitoring for at least 12 months,
decrease frequency, based on clinical judgement if
disease / dose stable
Alcohol-limit within national recommendations


                RCN Conference January 2009
              Methotrexate (2)
Pulmonary toxicity (1:108 pt yrs)
–    Potentially fatal hypersensitivity
–    Usually seen within 12 months of treatment
–   Incidence may be higher in pre existing lung disease
Pregnancy-
– Adequate contraception- withdraw mtx for 3 months
  before conception for both men and women. Avoid
  breast feeding
Infection-do not withdraw pre operatively


                    RCN Conference January 2009
               Leflunomide
Monitoring
– BP if>140/90 X 2 occasions 2 weeks apart, treat
  hypertension before commencement
– Weight -pre treatment and on each monitoring visit
– FBC and LFT’s monthly for 6 months, then if stable, 2
  monthly.
SPC states caution if used with MTX although
combination therapy is used. Monitor monthly



                  RCN Conference January 2009
             Leflunomide (2)
Pregnancy
– Teratogenic, requires adequate contraception.
– Females planning conception, withdraw treatment for 2
  years or use washout procedure. Avoid Breast feeding
– Men should continue adequate contraception for 3
  months after discontinuation of treatment.
Alcohol limit to within national limits (4-8 units
week)
Treat hypertension


                  RCN Conference January 2009
            Sulfasalazine
Time to response minimum 3/12
Transient reversible oligospermia
Can be prescribed in pregnancy
– Assess risk to mother /baby
– Prescribe folic acid supplement when trying to
  conceive and during pregnancy
– Small amounts excreted in breast milk, not
  thought to be a risk


               RCN Conference January 2009
         Sulfasalazine (2)
Monitoring
– FBC and LFT monthly for 3 months then 3
  monthly. If following the first year, dose and
  blood results have been stable -6 monthly for
  2nd yr of treatment. Thereafter monitoring can
  be discontinued
– Pts should be asked about the presence of rash
  or oral ulceration at each visit


               RCN Conference January 2009
         Other Investigations
Plain x-rays                 Pulmonary function
MRI                          tests
CT                           Biopsy – Muscle
Ultrasound                             Skin
Thermography                           Synovial
Arthrogram                 Bone scans
Arthroscopy                DEXA
Capilliary                 Synovial fluid analysis
microscopy                 Urine testing –Stick
Nerve conduction                 Bence Jones
studies                          24 hr collections
            RCN Conference January 2009
                Urinalysis
Routine dipstick urinalysis – should never be
underestimated
Can detect: Blood, protein, bilirubin
Indicated possible infection, active disease in
Lupus, other organ involvement – kidney or
liver
Used for drug monitoring – Gold,
Penicillamine, cyclophoshamide, ciclosporin,
biologic therapies
Should be done routinely for all new
admissions/clinic attenders
Is a case for urinalysis at every visit
              RCN Conference January 2009
Urine specimens and 24hr collections
  Bence Jones protein – A protein of low
  molecular weight found in the urine of
  patients with multiple myeloma, other bone
  tumours, amyloidosis and metastatic disease.
  24 hour collection
      Creatinine clearance
      Urinary protein
Used to assess disease and damage, for
example in Lupus.
Also as a baseline prior to commencing therapy

               RCN Conference January 2009
                 Conclusion
Multiple investigations available to health
professional

A full history will give a preliminary diagnosis in 70%
of cases
Investigations assist us in not only diagnosis, but
monitoring and assessing disease process and effect
of treatment.
Biomechanical measurement is only a small part of
assessment of disease –remember assessment of
pain, anxiety, depression, function, QOL

                 RCN Conference January 2009

				
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Description: BLOOD TESTS AND THEIR MEANINGS