Thrombocytopenia (Low platelet count)

 A reduced platelet count may arise by one of two mechanisms: 

• decreased or abnormal production (bone marrow failure and hereditary thrombocytopathies)
• increased consumption following release into the circulation (immune-mediated, DIC or sequestration).

Spontaneous bleeding does not usually occur until the platelet count falls below 20 × 109 /L, unless their function is also compromised. Purpura and spontaneous bruising are characteristic but there may also be oral, nasal, gastrointestinal or genitourinary bleeding. Severe thrombocytopenia (< 10 × 109 /L) may result in retinal haemorrhage and potentially fatal intracranial bleeding, but this is rare.

  Investigations are directed at the possible causes listed in below figure.

A blood film is the single most useful initial investigation. Examination of the bone marrow may reveal increased megakaryocytes in consumptive causes of thrombocytopenia, or the underlying cause of bone marrow failure in leukaemia, hypoplastic anaemia or myelodysplasia.

    Treatment (if required) depends on the underlying cause. Platelet transfusion is rarely required and is usually confined to patients with bone marrow failure and platelet counts below 10 × 109 /L, or to clinical situations with actual or predicted serious haemorrhage.