Androgenetic Alopecia: Symptoms, Diagnosis, and Treatment
Clinical Presentation
Androgenetic alopecia presents with distinct patterns: in women, progressive thinning occurs in the central scalp with centrifugal expansion (mid-scalp widening) or a frontal "Christmas tree" pattern, while the frontal hairline typically remains preserved; in men, characteristic bitemporal recession and vertex thinning occur. 1
The key clinical feature is progressive hair follicle miniaturization, where terminal hairs transform into shorter, finer vellus-like hairs. This process is driven by dihydrotestosterone (DHT) effects on genetically susceptible hair follicles 2, 3.
Diagnostic Approach
The diagnosis is primarily clinical, requiring careful scalp examination to identify the characteristic distribution pattern and miniaturized hairs. 1
Essential Diagnostic Steps:
Dermoscopy/Trichoscopy: Use this routinely for diagnosis, differential diagnosis, severity staging, and treatment monitoring 1, 4
- Look for hair diameter diversity, yellow dots, and perifollicular pigmentation
- Diagnostic criteria show 98.3% sensitivity and 96.7% specificity 4
Scalp biopsy: Reserve for cases where dermoscopy cannot differentiate from other hair loss conditions 1
Laboratory Evaluation:
In women with androgenetic alopecia, measure androgens using high-quality assays (LC/MS preferred) including total testosterone and free testosterone (via equilibrium dialysis or calculated using SHBG). 1
Additional useful tests (though not mandatory):
- Iron studies (ferritin)
- Vitamin D (25-hydroxyvitamin D)
- Zinc levels
- Thyroid profile
- Prolactin 1
Important caveat: Isolated androgenetic alopecia with normal androgen levels should NOT be considered a sign of hyperandrogenism 1. The relationship between iron deficiency and hair loss remains uncertain, and iron supplementation in patients with low-normal ferritin (<70 mg/L) has not shown benefit 1.
Treatment Algorithm
First-Line Treatment
Start with topical minoxidil 5% as first-line therapy for all patients with androgenetic alopecia. 1
- 5% formulations are superior to 2% 1
- 5% foam once daily equals 2% solution twice daily in efficacy 1
- Mechanism: prolongs anagen phase, triggers telogen-to-anagen transition, enlarges miniaturized follicles 5, 1
- Warn patients about transient increased shedding during weeks 2-8 of treatment 1
- Works for both central scalp and patchy hair loss 5
Low-dose oral minoxidil is increasingly used off-label and shows efficacy, though topical remains the approved standard. 5
Second-Line/Adjunctive Therapy
For severe hair loss, hyperandrogenism, or inadequate response to minoxidil alone, add 5α-reductase inhibitors or antiandrogens. 1
In Postmenopausal Women or Men:
- Finasteride 2.5-5 mg daily (lowest risk profile) 1
- Dutasteride (effective but limited clinical evidence) 1
- Spironolactone 100-200 mg daily (antiandrogen alternative, requires ≥12 months) 1
- Better response in women with concurrent hirsutism or acne 1
Critical Safety Point:
In women of reproductive age, 5α-reductase inhibitors and antiandrogens MUST be used with secure contraception due to teratogenic risk. 1
Avoid flutamide despite potential efficacy due to rare but serious hepatotoxicity 1
Emerging and Adjunctive Therapies
Low-level laser therapy (600-1550 nm wavelength) provides modest benefit with minimal side effects (headache, erythema, pruritus) 1
Platelet-rich plasma (PRP) shows promise but evidence remains limited with inconsistent protocols 1
Hair transplantation is effective but requires continued medical therapy post-procedure to prevent ongoing hair loss in non-transplanted areas 1
Treatment Pitfalls to Avoid
Don't assume all female pattern hair loss is androgen-driven: Only evaluate for hyperandrogenism if clinical signs are present or androgens are elevated 1
Don't supplement iron routinely: The evidence for iron deficiency causing androgenetic alopecia is weak, and supplementation doesn't improve outcomes even with low-normal ferritin 1
Don't use high-dose cyproterone acetate: Results are mixed and unclear 1
Don't forget contraception counseling: Teratogenic medications require absolute contraceptive security in reproductive-age women 1
Don't expect rapid results: Treatments require 6-12 months minimum for visible improvement; set realistic expectations