16. Hyperandrogenism: localising the source

First principle: separate the three "hairy" phenomena, then localise

• Hirsutism — terminal hair in an androgen‑dependent, male pattern → an androgen problem.
• Hypertrichosis — diffuse, non‑androgen‑dependent hair → not an androgen problem (drugs, systemic illness).
• Virilisation — hirsutism plus deepening voice, clitoromegaly, muscle bulk, temporal balding → marked androgen excess. 🚩

Localise by which androgen is elevated

• Testosterone → ovary (PCOS most commonly; rarely an ovarian tumour).
• DHEA‑S → adrenal (non‑classical CAH; adrenal tumour).

The discriminator that changes urgency

Assessment

• Modified Ferriman–Gallwey score (9 sites) to quantify and track.
• Consider 17‑OHP (non‑classical CAH), and imaging if tumour is suspected.

Pitfalls

• Reassuring a rapidly virilising woman as "PCOS" without measuring androgens/imaging.
• Forgetting non‑classical CAH as a PCOS mimic.

Pearls

• 🎯 Testosterone → ovary; DHEA‑S → adrenal. Rapid + virilising → tumour.
• 🩺 Idiopathic hirsutism (normal androgens, regular cycles) is common and benign — but a diagnosis of exclusion.

Next → The commonest cause, and the diagnostic rigour it demands (Concept 17).