Hair Loss with Testosterone Replacement Therapy in Women
Testosterone replacement therapy at physiologic doses does not cause hair loss in women and may actually improve scalp hair growth in androgen-deficient women. 1
Evidence Against TRT Causing Hair Loss
The New England Journal of Medicine explicitly states there is no data indicating acceleration of male-pattern baldness in patients receiving testosterone replacement therapy, though this has not been rigorously studied in controlled trials. 2, 1 This guideline evidence directly contradicts the common assumption that testosterone worsens hair loss.
In fact, testosterone therapy may improve hair growth in women with androgen deficiency:
- In a study of 285 women treated with subcutaneous testosterone implants for androgen deficiency, 27% reported hair thinning prior to treatment. 3
- Of those with pre-treatment hair loss, 63% reported hair regrowth on testosterone therapy. 3
- Critically, no patient in this cohort reported scalp hair loss as a result of testosterone treatment. 3
- Women who reported baseline hair loss had significantly lower serum testosterone levels than those without hair loss (P=0.0001). 3
Mechanism and Clinical Context
The beneficial effect appears related to testosterone's anabolic effect on hair follicles in androgen-deficient women. 3 This is fundamentally different from the androgenetic alopecia seen in:
- Female-to-male transgender patients receiving supraphysiologic testosterone doses (targeting 300-1,000 ng/dL) who have no prior androgen exposure. 1
- Women with female pattern hair loss who have increased testosterone production rates (9.4±5.0 μg/h vs normal 4.3±1.9 μg/h) but normal or low DHT production. 4
Management Approach
For women on TRT experiencing hair loss, the priority is ruling out other causes rather than stopping testosterone:
- Check thyroid function (TSH, free T4), iron stores (ferritin), vitamin D, and zinc levels. 2
- Examine for female-pattern hair loss, alopecia areata, or inflammatory (scarring) alopecia. 2
- Verify testosterone dosing targets mid-normal range, not supraphysiologic levels. 1
If hair loss persists despite normal labs and appropriate testosterone dosing:
- Consider oral antiandrogens (spironolactone 200 mg daily or cyproterone acetate 50-100 mg), which showed 88% of women had stabilization or improvement of hair loss. 5
- Note that 5α-reductase inhibitors are unlikely to help, as women with female pattern hair loss have normal or low DHT production despite elevated testosterone. 4
Key Clinical Pitfall
Do not automatically attribute hair loss to testosterone therapy. The evidence shows testosterone at replacement doses does not cause hair loss and may improve it in androgen-deficient women. 1, 3 Stopping or reducing testosterone based on this misconception may worsen both the underlying androgen deficiency symptoms and potentially the hair loss itself. 3
Monitoring Considerations
Standard TRT monitoring protocols do not include hair loss assessment as a routine parameter, focusing instead on PSA, hematocrit/hemoglobin, and clinical response to therapy. 1 Hair changes should prompt evaluation for alternative causes rather than automatic dose reduction. 2