Androgenic alopecia
Hair thinning in an androgen-driven pattern, usually at the crown and along the part. Common in PMOS, and often reversible when the underlying signal is addressed.
Androgenic alopecia is scalp hair thinning driven by androgens. In women with PMOS it tends to show at the crown and along the central part, while the frontal hairline is usually preserved. The hairs do not all fall at once; they miniaturise, growing back finer and shorter with each cycle until coverage thins.
The mechanism is the same one behind the other androgenic signs. Hair follicles on the scalp carry androgen receptors. When free testosterone is elevated, sensitive follicles respond by shrinking. The same hormone that drives terminal hair growth on the chin can drive thinning on the scalp.
Because the driver is hormonal rather than local, approaches that lower androgen load or improve insulin sensitivity often help, alongside dermatological options. It is worth raising early, since earlier intervention tends to preserve more.