Drug-Induced Alopecia — SCE Dermatology MCQ

Correct answer: B — Telogen effluvium

Telogen effluvium (option C) is the correct answer because sodium valproate characteristically pushes hair follicles prematurely out of the anagen (growth) phase into telogen (resting) phase, producing diffuse, non-scarring shedding rather than focal or scarring loss. This matches the stem exactly: a young woman on long-term valproate with diffuse, non-scarring hair loss developing over months, the classic latency (typically two to four months after starting therapy) for telogen effluvium. The mechanism is thought to relate to dose-dependent disruption of the normal hair cycle, and possibly interference with zinc and biotin metabolism, rather than direct follicular destruction. Hair loss is usually reversible on drug withdrawal or dose reduction, reinforcing the non-scarring, cycle-disruption nature of the process. Why the other options are wrong: E. Anagen effluvium: this occurs with agents that directly damage actively dividing hair matrix cells (classically cytotoxic chemotherapy), causing abrupt hair breakage within days to weeks; valproate does not act by this mechanism. C. Androgenetic alopecia: this is a patterned, hormonally mediated, progressive miniaturisation of follicles related to androgen sensitivity, not a diffuse drug-induced effluvium, and has no temporal or mechanistic link to valproate. A. Alopecia areata: this is an autoimmune, T-cell mediated attack on anagen follicles causing patchy, well-demarcated non-scarring loss, distinct from the diffuse pattern described and not attributable to valproate. D. Cicatricial alopecia: this involves permanent follicular destruction and scarring, which contradicts the stem's explicit description of non-scarring hair loss. Key point: Sodium valproate causes diffuse, non-scarring hair loss via telogen effluvium (premature entry into the resting phase), typically reversible after stopping or reducing the drug.

Reference: BNF (NICE), Sodium Valproate, Side-effects section: alopecia listed as a recognised adverse effect, https://bnf.nice.org.uk/drugs/sodium-valproate/