In a patient with a normal platelet count but abnormal platelet function tests, what disorders should be considered?

• A. Platelet Function Disorders (e.g., Glanzmann thrombasthenia) or aspirin/antiplatelet effects
• B. Hemophilia A
• C. Factor VII deficiency
• D. Liver Disease

Answer: (A)

When platelets are present in normal numbers but tests show they don’t work properly, the problem lies in platelet function itself or in drugs that impair that function. Platelet Function Disorders are a group of conditions where platelets can’t aggregate or form a proper plug, even though the count is normal. Glanzmann thrombasthenia is a classic example, caused by a defect in the GPIIb/IIIa complex that prevents platelet aggregation. In such cases, laboratory testing shows defective aggregation with multiple agonists, reflecting a qualitative defect in platelet function rather than a shortage of platelets.

Another important cause is aspirin or other antiplatelet drugs, which blunt platelet function by inhibiting thromboxane A2 or other pathways, leading to abnormal function tests despite a normal platelet count.

The other options point to problems with the coagulation cascade or liver-derived factors. Hemophilia A and Factor VII deficiency involve deficiencies in coagulation factors, so they disrupt secondary hemostasis rather than platelet function; platelet tests are typically not abnormal due to those issues. Liver disease can affect both coagulation factors and platelet function, and often coexists with low platelet counts, so it’s less consistent with normal platelet numbers paired with abnormal platelet function tests.