Platelet disorders Thrombocytopenia

Rarely symptomatic until the platelet count <50 x 109/l; spontaneous bleeding is more likely <20 x 109/l. Although bleeding is often minor, e.g. skin petechiae, oozing at intravascular catheter sites, it may be massive or life-threatening, e.g. haemoptysis, intracranial haemorrhage.

Causes

• Sepsis — in the ICU this is the commonest cause of a low platelet count; often provides a good barometer of recovery or deterioration

• Disseminated intravascular coagulation

• Related to antiplatelet antibody production, e.g. heparin (heparin-induced thrombocytopenia syndrome, 'HITS'), sulphonamides, quinine

• Resulting in bone marrow suppression, e.g. chemotherapy agents

• Others, e.g. aspirin, chlorpromazine, prochlorperazine, digoxin

• Following massive bleeding and multiple blood transfusions

• Bone marrow failure, e.g. tumour infiltration, drugs

• Splenomegaly

• Thrombotic thrombocytopenic purpura (TTP), haemolytic uraemic syndrome (HUS)

• Idiopathic thrombocytopenic purpura (ITP)

• Specific infections, e.g. measles, infectious mononucleosis, typhus

• Collagen vascular diseases, e.g. SLE

Management

1. Directed at the cause, e.g. antibiotics for sepsis, stopping offending drugs, plasma exchange for TTP, splenectomy and steroids for ITP.

2. Platelet support

• Given routinely (e.g. 6-10 units/day) when counts <10-20 x 109/l

• 6-10 units given if <50 x 109/l and either symptomatic or due to undergo surgery or another invasive procedure

3. Unless actively bleeding, avoid platelet transfusions in TTP or HUS.

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Responses

  • letizia
    How are low platelets and metabolic acidosis related?
    2 months ago

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