Blood test to investigate hair loss: what to know

Depending on your pattern of loss and other symptoms, a clinician may consider tests related to blood count, iron stores, thyroid function, nutrient status, hormones, or inflammation. Blood work can identify a contributor, but it cannot diagnose every type of hair loss. A scalp examination helps distinguish diffuse shedding from patchy loss, breakage, infection, or a condition affecting hair follicles. The timing of illness, childbirth, major stress, weight change, and medicines also matters.

Bring a list of medicines and supplements, describe when shedding began, and mention itching, scaling, pain, or bald patches. Avoid starting iron or hormone supplements before discussing testing, since treatment should match the cause. A clinician may recommend gentle hair care, correction of a confirmed deficiency, treatment for scalp inflammation, or referral to a dermatologist. Conditions such as anaemia and chronic kidney disease can be relevant to the wider assessment.

Book an appointment if hair loss is sudden, rapidly worsening, patchy, or accompanied by scalp redness, tenderness, sores, or scaling. Seek prompt care if it occurs with severe fatigue, fainting, unexplained weight change, or other new systemic symptoms. Emergency care is needed for breathing difficulty or facial swelling from a suspected medicine reaction.

Which causes fit my pattern of loss? Which blood tests are relevant? Could a medicine, recent illness, nutrition problem, or anaemia contribute? When should I expect follow-up, and should a dermatologist examine my scalp?