Valproate Thrombocytopenia — ORE Part 1 MCQ

Correct answer: D — Sodium valproate can cause dose-dependent thrombocytopenia as a side effect

The correct answer is D. Sodium valproate is a well-established cause of both thrombocytopenia (low platelet count) and platelet dysfunction. This adverse effect is dose-related, meaning higher doses carry greater risk. The patient's clinical presentation—gingival bleeding with a platelet count of 85 × 10⁹/L while on valproate—is classic for valproate-induced thrombocytopenia. Option B is incorrect because valproate does not increase platelet aggregation; it reduces platelet number and function. Option A is wrong as the evidence firmly establishes causation. Option E contradicts the known effect (valproate decreases, not increases, platelets). Option C is partially correct in that qualitative defects occur, but valproate causes quantitative defects too (the thrombocytopenia demonstrated in this case). Careful monitoring of platelet counts is recommended during valproate therapy, especially when doses exceed 40 mg/kg/day.

Reference: Winfield DA, Benton P, Espir ML, Arthur LJ. Sodium valproate and thrombocytopenia. British Medical Journal. 1978; https://pubmed.ncbi.nlm.nih.gov/6781890/; supported by recent real-world data: Prospective monitoring studies consistently demonstrate dose-dependent platelet count reduction during sodium valproate therapy.