Is high testosterone (hyperandrogenism) associated with hair loss?

Does High Testosterone Cause Hair Loss?

Yes, elevated testosterone—specifically its conversion to dihydrotestosterone (DHT)—is directly responsible for androgenetic alopecia (pattern hair loss), which affects up to 80% of men and 50% of women during their lifetime. 1, 2

The Mechanism: It's About DHT, Not Just Testosterone

The relationship between testosterone and hair loss is mediated through a critical metabolic conversion:

• Testosterone itself doesn't cause hair loss—rather, the enzyme 5-alpha reductase converts testosterone into dihydrotestosterone (DHT) within hair follicles 2, 3
• DHT is the culprit: This potent androgen metabolite causes progressive miniaturization of genetically-sensitive hair follicles, leading to the characteristic pattern of androgenetic alopecia 1, 2
• Local metabolism matters most: The dermal papilla cells within hair follicles contain steroidogenic enzymes (including type 2 5-alpha reductase) that perform this intrafollicular conversion, making local androgen metabolism more important than circulating testosterone levels 3

Clinical Manifestations by Sex

In men, androgenetic alopecia presents with:

• Bitemporal recession of the frontal hairline
• Diffuse thinning at the vertex
• Progression following the Hamilton-Norwood classification pattern 4, 2

In women, the pattern differs:

• Diffuse thinning of the crown region with preserved frontal hairline (Ludwig pattern)
• In premenopausal women, may indicate hyperandrogenism alongside hirsutism and acne 4, 2
• Central region thinning is characteristic 4

The DHT Paradox: Why Hair Loss on Scalp but Growth Elsewhere?

A critical nuance: DHT causes hair loss on the scalp but promotes hair growth in secondary body and facial hair locations 5. This paradox reflects:

• Genetic sensitivity varies by follicle location: Hair follicles from different body sites have different androgen sensitivity profiles 3
• The same hormone produces opposite effects depending on the anatomical location and genetic programming of the follicle 5

Serum Testosterone Levels Are Misleading

Important caveat: Measuring serum DHT or testosterone levels is not diagnostically useful for androgenetic alopecia:

• Increased serum DHT concentrations occur in both patients with androgenetic alopecia AND healthy controls without significant differences 6
• The key factor is genetically-determined follicular sensitivity to DHT, not circulating hormone levels 6
• Local intrafollicular androgen metabolism and receptor sensitivity determine hair loss, not systemic levels 3, 6

Evidence from Hormone Therapy Populations

Testosterone therapy in transgender men (female-to-male transition) confirms the androgen-hair loss relationship:

• Androgenic alopecia is listed as a common adverse effect of testosterone therapy 7
• This occurs despite targeting physiologic male testosterone ranges (300-1,000 ng/dL) 7

Conversely, in transgender women (male-to-female transition):

• Anti-androgen therapy combined with estrogen decreases body and facial hair growth 8, 9
• This demonstrates the reversibility of androgen-mediated hair effects when androgens are suppressed 8

Clinical Recognition in PCOS

In women with polycystic ovary syndrome (PCOS), hyperandrogenism manifests clinically through:

• Androgenic alopecia (alongside hirsutism and acne) as a diagnostic criterion 4
• Biochemical hyperandrogenism is present in 75% of PCOS cases 4
• The 2023 International PCOS Guidelines recommend measuring total testosterone and free testosterone as first-line tests for biochemical hyperandrogenism 4

Treatment Implications

FDA-approved treatments target the DHT pathway:

• Finasteride (1 mg daily in men) inhibits 5-alpha reductase, blocking testosterone conversion to DHT 1
• This treatment is superior to placebo (P < .00001) in meta-analysis 1
• Minoxidil (topical) and low-level laser therapy also show efficacy but work through different mechanisms 1, 2

The castration observation: Surgical castration (reducing androgen production by 95%) stops pattern hair loss progression but does not fully reverse it, indicating that while androgens initiate the process, additional factors (fibrosis, calcification, tissue remodeling) perpetuate it 5

Key Clinical Pitfalls to Avoid

• Don't order serum testosterone or DHT levels to diagnose androgenetic alopecia—diagnosis is clinical based on pattern recognition 6
• Don't assume normal testosterone levels exclude androgenetic alopecia—follicular sensitivity, not serum levels, determines hair loss 6
• Don't overlook the diagnosis in women—female pattern hair loss affects 50% of women and may indicate underlying hyperandrogenism requiring evaluation 2, 4
• Recognize that scalp dermoscopy facilitates diagnosis, staging, and monitoring of treatment response 2