Medical Term for Low Platelet Count
The medical term for low platelet count is thrombocytopenia, defined as a platelet count less than 150 × 10⁹/L (or 150,000/μL). 1, 2
Definition and Terminology
- Thrombocytopenia is the universally accepted medical term for a platelet count below 150 × 10⁹/L 1, 2, 3, 4
- The term has replaced older terminology such as "idiopathic thrombocytopenic purpura" (ITP), which is now called "immune thrombocytopenia" to reflect current understanding of the immune-mediated nature of the disease and the fact that many patients do not present with purpura (bleeding into the skin) 1
Clinical Severity Classification
The severity of thrombocytopenia is stratified based on platelet count thresholds:
- Mild thrombocytopenia: Platelet count >50 × 10⁹/L - patients are generally asymptomatic 2
- Moderate thrombocytopenia: Platelet count 20-50 × 10⁹/L - patients may develop mild skin manifestations such as petechiae, purpura, or ecchymosis 1, 2
- Severe thrombocytopenia: Platelet count <20 × 10⁹/L - significantly increased bleeding risk 1, 2
- Critical thrombocytopenia: Platelet count <10 × 10⁹/L - high risk of serious spontaneous bleeding including intracranial hemorrhage 1, 2
Important Clinical Context
- Pseudothrombocytopenia must be excluded first, as it occurs in approximately 0.1% of adults due to platelet clumping in EDTA-containing blood collection tubes 5, 6
- Thrombocytopenia can result from four main mechanisms: decreased platelet production, increased platelet destruction, splenic sequestration, or dilution 2, 3
- While classically associated with bleeding, certain thrombocytopenic conditions paradoxically cause both bleeding and thrombosis, including heparin-induced thrombocytopenia, antiphospholipid syndrome, and thrombotic microangiopathies 2