The diagnosis is primarily clinical, that is, based on findings at examining the patient.
The hairless patches are typically painless, smooth and circular, with short broken hairs around the edges.
The nails may also be involved, with roughening and pitting.
Rarely, the eye may be affected. Biopsy of affected sites is rarely needed.
Blood tests may be done to establish whether there are any underlying auto-immune conditions that may have precipitated alopecia and which might need to be treated.