investigations in primary care

Last reviewed 01/2018

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 (2)
• examine for splenomegaly
• if patient >60x109/l then should consider myelodysplasia as possible cause (3)
• 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:

1. GP magazine (August 8th 2004): 33-4.
2. George, J.N. For low platelets, how low is dangerous? Cleveland Clinic Journal of Medicine 2004;71(4): 277-278.
3. American Society of Hematology.Diagnosis and treatment of idiopathic thrombocytopenic purpura: recommendations of the American Society of Hematology. Annals of Internal Medicine 1997;126(4): 319-326.
4. Kam PC et al. Thrombocytopenia in the parturient, Anaesthesia 2004;59:255–264.