Investigations will be influenced by any presumed aetiology, but include:
- repeat FBC and request blood film
- this is in order to confirm thrombocytopenia is real - also this will exclude other diseases such as chronic lymphocytic leukaemia and myelodysplastic syndromes
- renal biochemistry
- liver function tests (liver disease)
- viral serology (EBV, hepatitis screen); consider HIV
- autoantibodies - thrombocytopenia may occur in conditions such as SLE
- B12, folate - deficiency may result in pancytopenia or cytopenia of particular cell line
- immunoglobulins - to exclude common variable immunodeficiency
- clotting studies - also related to liver function
Bone marrow will be a secondary care investigation.
Notes:
- if thrombocytopaenia is drug-induced then platelet counts will recover 5-7 days after stopping the incriminated drug
- if platelet count is < 30x10^9/l then this is an indication for stopping antiplatelet medication e.g. aspirin, clopidogrel
- examine for splenomegaly
- if patient >60x109/l then should consider myelodysplasia as possible cause
- gestational thrombocytopenia (GT) is considered the most prevalent cause of thrombocytopaenia in pregnancy
- accounts for about 75% of cases of thrombocytopenia during pregnancy
- defined by a platelet count of no less than 70 × 10^9/l, particularly during the third trimester
Reference:
- Provan D, Arnold DM, Bussel JB, et al. Updated international consensus report on the investigation and management of primary immune thrombocytopenia. Blood Adv. 2019 Nov 26;3(22):3780-817.