Haematology

at a Glance

Fourth EditionAtul B. Mehta and A. Victor Hoffbrand

Case Studies

Case 6: A 56-year-old woman with low platelets

A 56-year-old woman has a blood test performed to check her cholesterol level. The full blood count was found to be abnormal as follows:
Hb 147 g/L
White cells 7.6 × 109/L
Platelets 43 × 109/L
She is well and asymptomatic.
Physical examination was undertaken. She has occasional bruises over her legs, but no other abnormality is detected.

  • (a) What is the differential diagnosis?

    Correct answer: Causes of thrombocytopenia are discussed in Chapter 41. Likely causes in this patient include drugs or autoimmune thrombocytopenia. Myelodysplasia is unlikely as the red cells and white cells are normal. The patient is clinically well, and sepsis, disseminated intravascular coagulation (DIC) and thrombotic thrombocytopenic purpura (TTP) are therefore unlikely.

  • (b) What further specific questions would you ask in the history?

    Correct answer: The consequences of the thrombocytopenia should be documented. Does she bleed excessively? Thrombocytopenia can cause increased menstrual loss, bleeding from mucosal membranes, e.g. gums bleeding when brushing the teeth. Bruises can coccur and there may be a history of excessive bleeding in response to injury or following surgery. The potential causes of thrombocytopenia should also be explored. A drug history is important – drugs that can cause thrombocytopenia are discussed in Chapter 37 and include thiazide diuretics, antibiotics. Alcohol consumption should be documented. A family history should be taken as some causes of thrombocytopenia are inherited, e.g. von Willebrand disease.

  • (c) What tests would you do?

    Correct answer: Full blood count with blood film examination to exclude the presence of platelet clumps or red cell fragmentation indicative of microangiopathic haemolytic anaemia. Liver function tests, coagulation screen and routine biochemistry to include renal function. The direct antiglobulin test should be done to look for autoantibodies to red cells. Screening for connective tissue disturbances including an antinuclear and rheumatoid factors should be undertaken. Assessment of platelet antibodies can be undertaken in some centres, but these tests are usually difficult to perform and often give non-specific results. Screening for von Willebrand disease is done by assessing the level of von Willebrand factor. Hepatitis B and hepatitis C antibody status should also be assessed. Bone marrow examination should be considered.

  • (d) How would you treat her?

    Correct answer: The cause of thrombocytopenia should be established and treatment directed toward it. A causative drug should be replaced. If she has asymptomatic autoimmune thrombocytopenia she should simply be monitored. Treatment is not indicated unless the patient is at active risk of bleeding, e.g. platelets less than 20 × 109/L. She should avoid aspirin and non-steroidal anti-inflammatory drugs as they interfere with platelet function and could cause bleeding.

  • (e) 5. What precautions are required if she wishes to undertake air travel?

    Correct answer: The platelet count should be in excess of 20 × 109/L as there is an increased risk of bleeding when ambient air pressure is lower than at ground level. A short course of steroid therapy may be appropriate if she has autoimmune thrombocytopenia.

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