What this test measures
Dihydrotestosterone (DHT) is the 5α-reduced form of testosterone and is roughly 3–5× more potent at the androgen receptor than testosterone itself. It is produced peripherally — in genital skin, hair follicles, prostate and liver — by the enzyme 5α-reductase (types 1 and 2).
DHT is essential for male external genital development in utero, for puberty in boys, and for adult androgen-dependent traits — male-pattern balding, body hair, sebum production and prostate growth. The serum DHT assay (best done by LC-MS/MS) measures the circulating concentration.
Why it matters
DHT is a specialist test ordered in a small set of well-defined situations: confirming or excluding 5α-reductase type 2 deficiency in 46,XY children with undervirilised external genitalia; investigating delayed puberty in boys with normal testosterone; in some research and andrology workups; and to monitor patients on 5α-reductase inhibitors (finasteride, dutasteride) for prostate enlargement or pattern hair loss.
For everyday hirsutism, PCOS or testosterone-deficiency workup, total testosterone, free testosterone, SHBG, DHEA-S and A4 are the standard panel — DHT does not add much. In specialist endocrine clinics, the testosterone-to-DHT ratio is the key value: a ratio above 20 in a child with virilisation problems strongly suggests 5α-reductase deficiency.
How to prepare
Morning sample preferred (8–10 am). Fasting not required. Stop biotin and 5α-reductase inhibitors (finasteride, dutasteride) for the duration your doctor advises — sometimes 4–6 weeks if the goal is a baseline. Tell your doctor about any topical androgen products, testosterone gels and over-the-counter "T-booster" supplements.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Dihydrotestosterone (DHT) (ng/dL)[1][2] | Adult male: 16 – 79 ng/dL · Adult female: 4 – 22 ng/dL (assay-dependent) | Low DHT with normal testosterone (Testosterone:DHT ratio > 20) in a 46,XY child with undervirilised external genitalia is highly suggestive of 5α-reductase type 2 deficiency. In adult men on finasteride/dutasteride a low DHT is expected and confirms drug action. | Raised DHT can be seen with exogenous androgen use, congenital adrenal hyperplasia variants, or rare androgen-producing tumours. In adult men with normal testosterone, isolated DHT rises are uncommon. |
DHT — interpretation by clinical scenario
| Scenario | Testosterone | DHT | T:DHT ratio | Interpretation |
|---|---|---|---|---|
| 46,XY child, undervirilised | Normal/high | Low | > 20 | 5α-reductase type 2 deficiency |
| Adult male on finasteride | Normal | Low (50–70% suppression) | High | Expected drug effect |
| Healthy adult male | Normal | Normal | ~ 10:1 | Normal physiology |
| Exogenous androgen use | High | High | Variable | Aromatisable or 5α-substrate androgen |
| Male androgen-deficiency workup | Low | Low | Normal ratio | Primary hypogonadism — DHT adds little |
Frequently asked questions
I am losing hair — should I get my DHT measured?
For androgenetic alopecia (male or female pattern hair loss) a serum DHT level is not routinely useful — scalp DHT activity matters more than the blood level, and standard treatment (topical minoxidil; oral finasteride/dutasteride in men) is started on clinical grounds. Total/free testosterone, ferritin and thyroid function are more useful initial tests.
I am on finasteride for hair loss — will my DHT be low?
Yes, that is exactly the drug's mechanism. Finasteride suppresses DHT by about 60–70%, dutasteride by 90%. A low DHT on these drugs is expected and is not "abnormal" in your case.
Why is the test ordered in children?
In a 46,XY child (genetically male) born with undervirilised or ambiguous external genitalia, a low DHT with a high testosterone-to-DHT ratio after hCG stimulation suggests 5α-reductase type 2 deficiency — a treatable disorder of sexual development. This is a specialist paediatric endocrinology workup.
Will high DHT cause prostate cancer?
DHT drives benign prostate enlargement, and 5α-reductase inhibitors reduce prostate volume and lower-urinary-tract symptoms. The relationship with prostate cancer is more complex — finasteride lowers overall prostate cancer incidence but the magnitude and clinical significance has been debated. This is a clinical decision for your urologist.
I have PCOS — would DHT testing add anything?
Not routinely. The standard PCOS panel covers total/free testosterone, DHEA-S, A4, 17-OHP and SHBG. Serum DHT does not change management for typical PCOS.
Does DHT need to be done in the morning?
Yes — like testosterone, DHT has a mild diurnal rhythm, higher in the morning. Sample between 8 and 10 am for consistency.
Can supplements raise DHT?
Some "T-booster" and bodybuilding supplements contain DHT precursors or aromatase inhibitors that change the testosterone-DHT balance. If you are using such supplements, tell your doctor before the test.
Related Hormones / Endocrine tests
Tests commonly ordered alongside DIHYDROTESTOSTERONE (DHT), or that help interpret an unexpected result.
Sources & references
- NCBI StatPearls — Dihydrotestosterone · accessed 2026-05-30T00:00:00.000Z
- Mayo Clinic Laboratories — Dihydrotestosterone, Serum · accessed 2026-05-30T00:00:00.000Z
- Endocrine Society — Hirsutism in Premenopausal Women · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — Androgens · accessed 2026-05-30T00:00:00.000Z
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