What causes platelet disorders?

Updated: Nov 30, 2019
  • Author: Perumal Thiagarajan, MD; Chief Editor: Srikanth Nagalla, MBBS, MS, FACP  more...
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Platelet disorders can involve either a decreased number of platelets (thrombocytopenia) or defective platelet function. Functional disorders of platelets can be inherited (rare) or acquired (common). Platelet aggregation tests are useful in differentiating various disorders of platelet function. In all cases of thrombocytopenia, the peripheral blood smear must be reviewed to confirm the thrombocytopenia. This review is crucial.

Spurious thrombocytopenia can occur due to aggregates forming in the specimen. In addition, dilutional thrombocytopenia may occur in situations of fluid replacement or blood component replacement without platelet support.

Thrombocytopenia can be further divided into increased destruction or decreased production. Thrombocytopenia resulting from increased destruction occurs either by an immune mechanism or increased consumption.

Platelets are consumed intravascularly by the activation of the coagulation process (diffuse/disseminated intravascular coagulation [DIC]) or by deposition on damaged endothelial cells (microangiopathy). Production defects result from those diseases that cause bone marrow failure, such as aplastic anemia, infiltration by leukemia or another malignancy, fibrosis or granulomatous disorders, or tuberculosis.

Causes of thrombocytopenia related to increased destruction include (1) immune thrombocytopenias (eg, autoimmune, alloimmune, drug-induced) and (2) increased consumption (eg, DIC, TTP).

Causes of thrombocytopenia related to decreased production include bone marrow depression and inherited disorders. Genetic defects have been defined for 30 forms of inherited thrombocytopenia, but the underlying genetic or molecular mechanisms remain unidentified for nearly 50% of cases. [15]

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