Thrombocytopenia is defined as a platelet count below 150,000/µL. Which option states this threshold?

• A. A platelet count above 200,000/µL.
• B. A platelet count below 150,000/µL.
• C. A platelet count below 500,000/µL.
• D. A platelet count above 50,000/µL.

Answer: (B)

Thrombocytopenia is defined by having too few platelets, which impairs the blood’s ability to clot. The standard cutoff is a platelet count lower than 150,000 per microliter. When platelets fall below this level, clot formation is less reliable, increasing the risk of bleeding even with minor injuries. Normal platelet counts range roughly from 150,000 to 450,000 per microliter, so crossing below 150,000 marks the condition. Other options describe counts that are either within or above the normal range or set thresholds that do not correspond to the definition of thrombocytopenia, so they don’t define the condition.