Generalised reduction in scalp hair density rather than one sharply defined bald patch.
Diffuse thinning means the hair looks reduced across a broad area of the scalp. In women it may be female pattern hair loss, telogen effluvium, diffuse alopecia areata, nutritional deficiency, medication-related shedding, or a combination. In men, diffuse thinning can still be androgenetic alopecia, but diffuse unpatterned loss may raise concerns about donor area stability if hair transplantation is being considered. Diagnosis relies on the history, pattern, scalp examination, trichoscopy and sometimes blood tests or biopsy. The treatment depends on the underlying cause, so guessing can waste valuable time.
DermNet: Trichoscopy of generalised noncicatricial hair loss — https://dermnetnz.org/topics/trichoscopy-of-generalised-noncicatricial-hair-loss; British Association of Dermatologists: Hair loss female pattern (androgenetic alopecia) — https://www.bad.org.uk/pils/hair-loss-female-pattern-androgenetic-alopecia; Starace M et al. Female Androgenetic Alopecia: Diagnosis and Management, Am J Clin Dermatol, 2020 — https://doi.org/10.1007/s40257-019-00479-x
