Thrombocytosis causes increased ______

• A. Viscosity
• B. Bleeding tendency
• C. Coaguability
• D. Platelet aggregation

Answer: (C)

More platelets mean more surface and substances to drive clot formation. Platelets provide the phospholipid surface on which coagulation factors assemble, and they release procoagulant mediators that promote thrombin generation and fibrin formation. This increases the blood’s tendency to clot, i.e., coagulability.

Viscosity is not primarily driven by platelet count; it’s more influenced by hematocrit and plasma proteins. Bleeding tendency is not the typical outcome of thrombocytosis—usually the opposite, with a tendency toward thrombosis, though rare functional abnormalities can cause bleeding in some cases. Platelet aggregation is a related function of platelets, but the general effect of thrombocytosis is best described as increased coagulability.