Blood Tests for Hair Loss
Hair loss often has an underlying cause that blood tests can identify. Low iron, thyroid issues, and vitamin deficiencies are treatable culprits.
Educational Information Only
This guide is for educational purposes and does not constitute medical advice. Hair loss has many causes including genetics (androgenetic alopecia), autoimmune conditions (alopecia areata), and scarring conditions. A dermatologist can provide proper diagnosis, which may include scalp biopsy in addition to blood tests.
Key insight: Ferritin (iron stores) can be low enough to cause hair loss while still being in the "normal" lab range. Many dermatologists want ferritin above 70 ng/mL for optimal hair growth, not just above 12.
Primary Labs to Request
Ferritin (Iron Stores)
IronLow ferritin is one of the most common causes of hair loss in women. Hair follicles are highly sensitive to iron levels. You can have low ferritin WITHOUT being anemic.
Target: Above 30 ng/mL minimum; many dermatologists target 70+ for hair regrowth.
Thyroid Panel (TSH, Free T4, Free T3)
ThyroidBoth hypothyroidism and hyperthyroidism cause hair loss. Thyroid affects hair growth cycle. Hair loss is often diffuse (all over) rather than patchy.
Target: TSH 0.4-4.0 mIU/L, but hair loss can occur even with "normal" TSH in Hashimoto's.
Vitamin D
VitaminsVitamin D receptors are present in hair follicles. Deficiency is linked to alopecia areata and telogen effluvium (diffuse shedding).
Target: Above 30 ng/mL; some dermatologists prefer 50-70 ng/mL for hair health.
Vitamin B12 & Folate
VitaminsB12 deficiency affects DNA synthesis in rapidly dividing cells like hair follicles. Common in vegetarians, vegans, and those on metformin.
Target: B12 above 300 pg/mL; folate above 3 ng/mL.
Zinc
MineralsZinc is essential for hair growth and repair. Deficiency causes hair loss and can impair hair regrowth. Common in vegetarians and those with GI issues.
Target: 60-120 mcg/dL
Complete Blood Count (CBC)
BloodAnemia from any cause can trigger hair loss. The CBC also helps identify underlying conditions affecting hair growth.
Target: Hemoglobin above 12 g/dL (women), 14 g/dL (men).
Hormone Tests (For Pattern Hair Loss / PCOS)
If you have pattern hair loss (thinning at crown/temples), your doctor may also check:
Types of Hair Loss & Relevant Labs
Track Your Labs Over Time
Upload your lab results to monitor ferritin, thyroid, and vitamin levels as you address hair loss.
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