Thrombocytopenia
Thrombocytopenia is an abnormally low platelet count in the blood. It can impair clot formation and increase the risk of bleeding.
Megakaryocyte: A large bone-marrow cell that produces platelets by releasing fragments of its cytoplasm. Reduced megakaryocyte development or platelet release can lower circulating counts.
Platelet: A small, nucleus-free blood component that helps form clots and repair damaged blood vessels. Thrombocytopenia is defined by having too few of these circulating cell fragments.
Pseudothrombocytopenia: A falsely low platelet count caused by platelet clumping in a blood sample rather than a true reduction in the body. It must be distinguished from genuine thrombocytopenia before treatment decisions.
Thrombocytosis: An abnormally high number of platelets in the blood. It is the count-based opposite of thrombocytopenia.
Heparin-induced thrombocytopenia: An immune reaction to heparin that activates platelets, lowers their count, and raises the risk of thrombosis. This drug-related case is notable because clotting, rather than bleeding, is the principal danger.
Thrombopoietin: A hormone that regulates platelet production by stimulating megakaryocytes and their precursors. Disrupted thrombopoietin signaling can reduce platelet production.
Complete blood count: A blood test that measures red cells, white cells, hemoglobin, and platelets. Its platelet result commonly identifies a low count.
Peripheral blood smear: A microscope examination of blood cells spread thinly across a glass slide. It can reveal platelet clumps, unusually large platelets, or other clues behind a low count.
Pancytopenia: A reduction in red cells, white cells, and platelets in the blood. A low platelet count accompanied by reductions in other blood cells suggests a broader disorder.
Gestational thrombocytopenia: A usually mild, late-pregnancy decline in platelet count without another identified cause. It is a common pregnancy-associated case, typically distinct from severe maternal platelet disorders.