Which condition is an example of a qualitative platelet defect?

• A. Uremia
• B. Iron deficiency
• C. Thrombocytopenia due to aplastic anemia
• D. Vitamin K deficiency

Answer: (A)

Qualitative platelet defects are problems with how platelets work, not how many are present. Uremia from kidney failure leads to accumulation of toxins that impair platelet adhesion and aggregation, so bleeding occurs even though the platelet count is normal and the coagulation tests are usually normal. This makes uremia a classic example of a qualitative platelet defect. In contrast, iron deficiency typically causes a change in platelet count (often thrombocytosis) rather than a primary dysfunction of platelet function; aplastic anemia lowers the platelet number (quantitative defect); and vitamin K deficiency affects the coagulation cascade (secondary hemostasis) rather than platelet function.