GPAtlas🧭 When to suspect
Male pattern hair loss (androgenetic alopecia) is the commonest cause of hair loss in men, affecting around half of men by 50 and the majority by 70. It is an androgen-dependent, genetically determined process: in susceptible follicles, dihydrotestosterone (DHT) – produced from testosterone by the enzyme 5-alpha reductase – drives progressive follicular miniaturisation, so each successive hair grows finer, shorter and less pigmented until the follicle stops producing a visible hair.
The diagnosis is clinical. Suspect it in a man describing gradual, painless thinning with bitemporal recession of the hairline and loss over the crown (vertex), on a scalp that is otherwise normal – no scaling, no inflammation and no scarring. Around one in ten men instead show a “female” pattern: diffuse thinning over the crown with a widening central parting but a preserved frontal hairline.
The two practical skills in primary care are to recognise the typical pattern confidently – sparing unnecessary investigation – and to spot the features that point to a different cause, some of which are reversible or follicle-destroying.
| Presentation | Suggests |
|---|---|
| Gradual bitemporal recession and vertex thinning on a non-inflamed, non-scarred scalp | Male pattern hair loss (androgenetic alopecia) |
| Diffuse shedding 2–3 months after a trigger (illness, surgery, childbirth, crash diet, severe stress) | Telogen effluvium – usually self-limiting |
| Well-defined, smooth, round bald patches ± short tapering “exclamation-mark” hairs | Alopecia areata |
| Redness, scaling, pustules, or loss of follicular openings with scarring | Cicatricial (scarring) alopecia – irreversible; refer early |
| Frontal hairline recession with eyebrow loss, typically in a post-menopausal woman | Frontal fibrosing alopecia |
| Loss confined to the margins or sites of tight or pulled hairstyles | Traction alopecia |
Source: NICE · DermNet
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