Testosterone Suppression on HRT: What the Target Actually Is

One of the most common misconceptions in trans healthcare is that the goal of testosterone suppression is to eliminate testosterone entirely. It is not. The goal is to bring testosterone into the normal female reference range — and understanding what that means in practice requires more than looking at a single number on a blood panel.

What the guidelines say

Current Endocrine Society Clinical Practice Guidelines recommend a target testosterone level of less than 50 ng/dL (1.7 nmol/L) for trans women on feminising HRT. WPATH SOC-8 similarly recommends suppression to within the female normal range. The female reference range itself varies considerably by laboratory and assay — commonly cited ranges include approximately 10–55 ng/dL, 15–70 ng/dL, or 20–80 ng/dL depending on the method used. The guideline target of below 50 ng/dL is more standardised than laboratory reference ranges, and is the appropriate clinical benchmark.

The goal is not zero. Testosterone is a physiologically normal hormone in women at low concentrations, with roles in bone density, libido, and metabolic function. Suppression below female range is not the aim and is not necessary for feminisation.

Why suppression can be difficult

Testosterone suppression in trans women is usually achieved through some combination of oestradiol-mediated suppression of gonadotropins (oestradiol suppresses LH and FSH, reducing testicular output) and antiandrogen medications that block testosterone’s effects or further reduce its production. Not everyone needs both — some people achieve adequate suppression on oestradiol alone, without an antiandrogen.

In one cohort of 98 transgender women treated with oral oestradiol and spironolactone, only the highest suppressing quartile reliably achieved testosterone in the female range (mean 27 ng/dL); the remaining three-quarters showed substantial reductions from baseline but did not consistently reach the <50 ng/dL guideline target. Individual variability in response is substantial — the same dose and formulation can produce very different suppression outcomes between individuals.

Route of administration and suppression

Injectable oestradiol can achieve testosterone suppression without antiandrogens in many individuals and may be useful when suppression is inadequate with other regimens. A 2025 study found target testosterone suppression in 82.6% of patients on injectable oestradiol monotherapy. However, comparative data between routes remain limited, and injectables should not be assumed to uniformly outperform optimised oral or transdermal regimens across all patients.

If testosterone is not suppressing adequately on your current regimen, route of administration, antiandrogen choice, and dose are all clinically meaningful variables to review with your prescriber. Timing, adherence, assay method, and medication interactions should also be reviewed before concluding that a regimen has failed.

Which measure to monitor

Total testosterone is the standard monitoring measure. Endocrine Society guidelines recommend total testosterone alongside oestradiol as the routine blood panel for feminising HRT. Free testosterone — calculated using SHBG and albumin — is not part of routine monitoring and is reserved for specific circumstances such as suspected protein-binding abnormality, unusually high SHBG, or discordance between total testosterone results and the clinical picture.

Many people become concerned about free testosterone and SHBG after reading about hormone binding. For most people on standard HRT monitoring, total testosterone interpreted against the guideline target of below 50 ng/dL is the appropriate clinical measure.

Interpreting your result correctly

This is where blood panels frequently mislead people. Labs typically report testosterone against male reference ranges by default. A result described as “low-normal” on a male range chart may still be above the therapeutic target for feminising HRT. Your result must be interpreted against the guideline target of below 50 ng/dL — not against a male population reference range.

Clinical signs of inadequate suppression

Persistent spontaneous erections, oily skin, acne, worsening androgenic scalp hair loss, or laboratory testosterone levels above target may suggest inadequate androgen suppression. Physical changes such as facial hair and breast development are influenced by many factors — genetics, age, duration of therapy, and individual variation — and are not reliable indicators on their own. Existing facial hair, in particular, can persist even with excellent testosterone suppression; the best achievable outcome is slower growth and finer texture, not disappearance. Breast development is similarly poor as a standalone marker of suppression status.

Monitoring requires measuring, not assuming. If you have not had testosterone checked recently, or if your result has only ever been interpreted against a male reference range, it is worth revisiting with your prescriber.

Sources

1. Hembree WC, Cohen-Kettenis PT, Gooren L, Hannema SE, Meyer WJ, Murad MH, Rosenthal SM, Safer JD, Tangpricha V, T’Sjoen GG. Endocrine Treatment of Gender-Dysphoric/Gender-Incongruent Persons: An Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism. 2017;102(11):3869–3903.
2. Coleman E, Radix AE, Bouman WP, et al. Standards of Care for the Health of Transgender and Gender Diverse People, Version 8. International Journal of Transgender Health. 2022;23(S1):S1–S259.
3. Liang JJ, Jolly D, Chan KJ, Safer JD. Testosterone Levels Achieved by Medically Treated Transgender Women in a United States Endocrinology Clinic Cohort. Endocrine Practice. 2018;24(2):135–142.
4. Misakian AL, Ariel D, Sullivan EA, Singh G, Loeb D, Strickland T, Iwamoto SJ, Rothman MS, Botzheim B, Liang JW, Kelley C, Hamnvik OR. Injectable Estradiol Monotherapy Effectively Suppresses Testosterone in Gender-Affirming Hormone Therapy. Endocrine Practice. 2025;31(11). DOI:10.1016/j.eprac.2025.07.002