Diagnosis and Tests for Hair Loss

A doctor usually diagnoses the cause of hair loss from history, scalp examination and a few targeted tests.

History and examination

Expect questions about when shedding began, recent illness, fever, childbirth, surgery, diet, new medicines, stress, periods and family history. The doctor will check the scalp, the parting width, the hairline and any patches.

Simple bedside tests

• Pull test: a gentle tug on a bunch of hair to check how easily it comes out.
• Dermoscopy (trichoscopy): a magnified look at follicles and hair shafts, which helps separate pattern loss, alopecia areata and scarring types.
• Hair count or photos: to follow change over time.

Blood tests, chosen by the doctor

• Complete blood count and ferritin (iron stores)
• Thyroid function (TSH)
• Vitamin B12 and vitamin D
• Blood sugar, and hormones such as testosterone or prolactin if a hormonal cause is suspected, for example with irregular periods
• Antinuclear antibody if lupus is a concern

Other tests

A scalp scraping or culture for a suspected fungal infection, and a scalp biopsy when scarring alopecia is possible.

Why not skip tests

Treating pattern hair loss with a product while iron deficiency or thyroid disease goes unchecked can waste months.

Key point

Ask for ferritin, thyroid and B12 checks if shedding is diffuse. These are common, treatable findings.

Before your appointment

Note when shedding began, how much you lose, and any recent illness, fever, surgery, crash diet, new medicine or stress. Bring recent blood reports such as ferritin, thyroid, B12 and vitamin D, a list of the products you use, and monthly photos of your parting. Mention any family history of hair loss or autoimmune disease.