Hair Loss Blood Test Panel (Iron, Ferritin, Thyroid, Vitamin D, B12 & Androgens)

Nine tests: a complete blood count with differential (anemia and red cell indices); ferritin (stored iron); serum iron, total iron binding capacity and transferrin saturation; TSH and free T4 (thyroid function); 25-hydroxy vitamin D; vitamin B12; free and total testosterone by mass spectrometry and equilibrium dialysis; and DHEA-sulfate (an androgen made mainly by the adrenal glands).

Women and men with new or increased shedding, a widening part, or thinning on the top of the scalp; women with thinning hair alongside irregular periods, acne or extra facial or body hair, which can suggest androgen excess or PCOS; people with heavy periods, a vegetarian or vegan diet, or past bariatric surgery who may be low in iron or B12; people with known or suspected thyroid disease; and anyone whose dermatologist or clinician wants these baseline labs.

Further reading: Ferritin vs Iron: Which Test Do You Actually Need?; The Complete PCOS Lab Tests Panel Your Doctor Should Order.

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When shedding or thinning is new, sudden or getting worse, ideally before starting supplements so the results reflect your baseline, and before or alongside a dermatology visit. Because thyroid and iron problems are treatable, earlier is better. Book a morning appointment, ideally between 7 and 10 a.m., after a 12-hour fast: iron requires a fasting morning sample, and testosterone is usually measured in the morning when it is highest.

Each result answers a different question. Low ferritin, with or without low iron, saturation or hemoglobin, points to low iron stores, a recognized and treatable contributor to shedding; the next step is finding why iron is low. A high or low TSH, read with free T4, suggests an underactive or overactive thyroid that needs a clinician's evaluation. Low vitamin D or B12 can be corrected and is worth treating whether or not it is the cause of your hair loss. In women, high testosterone or DHEA-S suggests androgen excess and usually leads to further evaluation for PCOS or an adrenal cause. If everything is normal, a blood-based cause is less likely, and the most common explanations are hereditary hair loss or temporary shedding after a stressor; a dermatologist diagnoses these by examining the scalp. JustLabs results are informational: review them with a clinician or dermatologist before starting any treatment or supplement.