Platelet count (PLT)

Platelet count is a fundamental clinical laboratory measurement that quantifies the concentration of thrombocytes (platelets) in the blood, typically reported as the number of cells per microliter (µL). Platelets are non-nucleated cell fragments derived from megakaryocytes in the bone marrow and are essential for primary hemostasis, where they aggregate at sites of vascular injury to form a platelet plug (StatPearls, NBK534811). While platelet count is a physiological parameter and biomarker rather than a specific molecular target like a receptor or enzyme, it is the primary clinical endpoint for therapies that modulate platelet production. Drugs such as thrombopoietin receptor (MPL) agonists are utilized to raise platelet counts in conditions like immune thrombocytopenia (ITP) and chronic liver disease, whereas cytoreductive therapies are used to lower counts in myeloproliferative disorders (NIH, NCI Dictionary). Monitoring the platelet count is critical for assessing risks of spontaneous hemorrhage when counts are pathologically low or thrombotic events when counts are excessively high (Mayo Clinic).

Other names

Thrombocyte countPLT countPeripheral platelet countBlood platelet count

Pharmacological modulation of platelet count is achieved by stimulating the thrombopoietin receptor (MPL) to increase megakaryocyte proliferation and platelet shedding, or by inhibiting megakaryocyte maturation and DNA synthesis to decrease platelet production (FDA, Nplate/Promacta Prescribing Information).