We do not need to do a skin biopsy to diagnose hair loss in most cases. Common causes of hair loss such as male and female pattern hair loss, telogen effluvium and aloepcia areata are usually diagnosed clinically without a need for biopsy.
In cases of scarring alopecia, where there is destruction of the hair follicles and in cases where the diagnosis is uncertain, a skin biopsy will usually be needed.