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Blood Tests for Hair Loss: Finding the Root Cause

By the EllaDx team · Updated December 30, 2025 · 1 min read

For education only, not a diagnosis. Talk to your clinician about your results.

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Seeing more hair in your brush than usual? Hair loss in women can have an underlying medical cause that blood tests can help identify.

What Can Cause Hair Loss

  • Thyroid dysfunction: Both hypo and hyperthyroidism can cause hair loss
  • Iron deficiency: May be one of the most common causes in women
  • Hormonal imbalances: Excess androgens, perimenopause
  • Nutrient deficiencies: B12, vitamin D, zinc, biotin
  • Autoimmune conditions: Alopecia areata, lupus
  • Stress: Telogen effluvium from major stressors

The Hair Loss Lab Panel

Thyroid

  • TSH, Free T3, Free T4
  • TPO and Thyroglobulin antibodies

Iron

  • Ferritin (may be optimal at >70 ng/mL for hair)
  • Complete iron panel

Hormones

  • Testosterone (total and free)
  • DHEA-S
  • Estradiol
  • Progesterone

Nutrients

  • Vitamin D
  • Vitamin B12
  • Zinc
  • Biotin

Other

  • ANA (antinuclear antibody) if autoimmune suspected
  • CBC to check for anemia

The Ferritin-Hair Connection

Research may suggest that ferritin levels below 70 ng/mL may contribute to hair loss, even when hemoglobin is normal. Many dermatologists may recommend ferritin >70 ng/mL for optimal hair health.

References

  • Trost, L. B., et al. (2006). The diagnosis and treatment of iron deficiency and its potential relationship to hair loss. Journal of the American Academy of Dermatology, 54(5), 824-844. PMID 16635664
  • Kantor, J., et al. (2003). Decreased serum ferritin is associated with alopecia in women. Journal of Investigative Dermatology, 121(5), 985-988. PMID 14708596
  • Olsen, E. A., et al. (2010). Iron deficiency in female pattern hair loss, chronic telogen effluvium, and control groups. Journal of the American Academy of Dermatology, 63(6), 991-999. PMID 20947203