A platelet count that falls below the lower limit of normal, i.e., 150000/microliter (for adults) is defined as thrombocytopenia. Platelets are blood cells that help in blood clotting and wound healing — risks associated with thrombocytopenia range from no risk at all to bleeding risks and thrombosis. The correlation of severity of thrombocytopenia and bleeding risk is uncertain. Spontaneous bleeding can occur with a platelet count under 10000/microliter and surgical bleeding with counts below 50000/microL. Thrombocytopenia is associated with risk of thrombosis in conditions like heparin-induced thrombocytopenia (HIT), antiphospholipid antibody syndrome (APS), disseminated intravascular coagulation (DIC), thrombotic microangiopathy (TMA), paroxysmal nocturnal hemoglobinuria (PNH).
Jinna S, Khandhar PB. Thrombocytopenia. 2022 Jul 5. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 31194365.