Hormonal Workup for Female Hair Loss
In all women presenting with female pattern hair loss (FPHL), androgen assessment is mandatory, while testing for vitamin D, iron, zinc, thyroid hormones, and prolactin is optional but recommended 1.
Mandatory Androgen Testing
The cornerstone of hormonal evaluation in FPHL requires assessment of androgen excess, even though most women with FPHL will have normal androgen levels 1. This is critical because:
- Total testosterone should be measured using high-quality assays, preferably liquid chromatography/mass spectrometry (LC/MS) or immunoassays with sample extraction and purification 1
- Free testosterone should be measured using equilibrium dialysis, ultracentrifugation, ammonium sulfate precipitation, or estimated using SHBG 1
- DHEAS (dehydroepiandrosterone sulfate) helps assess adrenal androgen contribution 1
A critical interpretation point: Isolated FPHL with normal androgen levels should NOT be considered a sign of hyperandrogenism 1. Most women with FPHL have normal circulating androgens and lack other hyperandrogenic features like hirsutism or menstrual irregularities 1.
Emerging Biomarker
Recent evidence suggests 3α-androstanediol glucuronide (3α-diol G) is significantly elevated in FPHL patients and correlates with clinical severity 2. This peripheral androgen metabolite showed high diagnostic accuracy (sensitivity 82%, specificity 73%) with a cut-off ≥5.242 nmol/L, outperforming traditional androgen measurements 2. While not yet in standard guidelines, this marker may prove valuable for detecting peripheral hyperandrogenism when standard androgens are normal.
Optional But Recommended Tests
Thyroid function: TSH and thyroid antibodies (anti-TPO) should be checked, as thyroid disorders frequently coexist with FPHL 1. Studies show elevated anti-TPO antibodies in 17.3% of FPHL patients 3.
Prolactin: Elevated levels may indicate underlying endocrine disorders, though the relationship with FPHL remains unclear 1.
Iron studies: The evidence is mixed regarding iron deficiency and FPHL 1. While some studies show lower ferritin in FPHL patients, others found no significant difference. Importantly, iron supplementation in patients with low-normal ferritin (<70 mg/L) did not improve hair loss 1. Check ferritin, but recognize its uncertain therapeutic relevance.
Vitamin D: Frequently low in FPHL patients (62% in one study), though causality is unproven 1.
Zinc: Lower levels reported in FPHL patients (15% deficient), but controlled studies on treatment efficacy are lacking 1.
Clinical Context Matters
When to test more extensively: Consider comprehensive androgen workup when FPHL is accompanied by:
- Moderate to severe hirsutism
- Menstrual dysfunction
- Sudden onset or rapidly progressive hair loss
- Signs of virilization (clitoromegaly, voice deepening)
- Obesity or metabolic concerns
These features suggest possible PCOS or other hyperandrogenic disorders requiring full evaluation 4, 5.
When androgens are elevated: If total testosterone is elevated, this helps delineate the cause of hyperandrogenism and may require imaging (pelvic ultrasound for PCOS, adrenal imaging if DHEAS markedly elevated) 5.
Common Pitfalls
Don't over-interpret normal results: Up to 40% of FPHL patients report symptoms suggestive of hormonal disorders (menstrual irregularities, hirsutism, acne), yet hormone tests often return normal 3. The absence of biochemical hyperandrogenism doesn't exclude FPHL.
Don't rely on testosterone alone: Free androgen index (FAI = total testosterone/SHBG × 100) may be more sensitive than testosterone or SHBG alone for detecting hyperandrogenism in FPHL 6. SHBG is frequently elevated (38.8% of cases), which can mask free testosterone elevation 3.
Assessment is primarily clinical: The diagnosis of FPHL relies on clinical pattern recognition (centrifugal mid-scalp expansion or frontal "Christmas tree" pattern), not hormonal abnormalities 1. Hormonal testing identifies treatable comorbidities and guides therapy selection, not diagnosis.
Practical Algorithm
- All FPHL patients: Total testosterone (LC/MS preferred), free testosterone or FAI (calculated from SHBG), DHEAS
- Add routinely: TSH, ferritin, vitamin D, prolactin
- Add selectively: Zinc if dietary deficiency suspected; LH/FSH if menstrual irregularities; anti-TPO if TSH abnormal
- Consider 3α-diol G: If available and standard androgens normal but clinical suspicion for androgen-mediated disease remains high
- Imaging: Only if biochemical abnormalities detected (pelvic ultrasound for elevated testosterone/LH:FSH ratio; adrenal imaging for markedly elevated DHEAS)