Dihydrotestosterone (DHT) Test
The dihydrotestosterone (DHT) test measures the most potent endogenous androgen, formed from testosterone by 5-alpha reductase in target tissues. It is used to investigate 5-alpha reductase deficiency, monitor 5-alpha reductase inhibitor therapy, and evaluate androgen-driven conditions such as androgenetic alopecia and hirsutism.
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Biomarkers
Blood (serum)
Sample
3–5 business days
Turnaround
No — however, an early-morning sample is reasonable given androgen diurnal variation, and testosterone is usually measured concurrently
Fasting
What is the DHT test?
The DHT Test measures dihydrotestosterone, the most potent androgen, formed from testosterone by 5-alpha reductase in target tissues. It is ordered to assess potent androgen activity and to investigate disorders of androgen metabolism, complementing testosterone measurement in the androgen workup. Within androgen assessment, DHT has a more specialised role than total testosterone. It is informative where the conversion of testosterone to its more potent metabolite is in question — for example in suspected 5-alpha reductase deficiency, where genital development is affected and the testosterone-to-DHT ratio is characteristically elevated — and in monitoring 5-alpha reductase inhibitor therapy used for benign prostatic enlargement or hair loss, which markedly lowers DHT. It contributes to the evaluation of androgenetic alopecia and hirsutism, though serum DHT incompletely reflects the local tissue androgen exposure that drives these. Because DHT circulates at low concentrations, mass-spectrometry measurement is preferred for accuracy, and results are interpreted alongside testosterone and the testosterone-to-DHT ratio.
What does the DHT test measure?
Dihydrotestosterone is the most potent endogenous androgen, formed from testosterone by the enzyme 5-alpha reductase in target tissues including the prostate, skin, hair follicles, and genital tissue. It binds the androgen receptor with substantially greater affinity than testosterone and drives androgen-dependent processes such as male external genital development, prostate growth, sebum production, and androgenetic hair patterning. Circulating DHT is lower in concentration than testosterone and is largely protein-bound; much of its action is local, generated within target tissues rather than reflected fully in serum.
DHT is measured to assess androgen activity in conditions driven by potent androgen action — androgenetic alopecia, hirsutism, benign prostatic processes — and to investigate disorders of androgen metabolism such as 5-alpha reductase deficiency, where DHT is low relative to testosterone. It is also used to monitor 5-alpha reductase inhibitor therapy, which lowers DHT. Because much DHT action is intracellular, serum DHT incompletely reflects tissue androgen exposure, and accurate measurement (preferably by mass spectrometry) is important given its low concentration.
Why is the DHT test ordered?
- Investigation of suspected 5-alpha reductase deficiency, where DHT is low relative to testosterone and the testosterone-to-DHT ratio is elevated
- Assessment of disorders of sexual development involving androgen metabolism, interpreted with testosterone
- Monitoring of 5-alpha reductase inhibitor therapy (finasteride, dutasteride), which substantially lowers DHT
- Evaluation of androgenetic alopecia where potent androgen activity is being assessed
- Investigation of hirsutism or androgenic symptoms in women as part of an androgen profile
- Assessment of androgen activity in benign prostatic processes where DHT's role is clinically relevant
- Characterisation of androgen metabolism alongside testosterone where the testosterone-to-DHT ratio is informative
Sample collection and turnaround
Sample type
Blood (serum)
Fasting required
No — however, an early-morning sample is reasonable given androgen diurnal variation, and testosterone is usually measured concurrently
Collection method
Venipuncture at patient service centre
Turnaround
3–5 business days
Collection notes
Measure DHT alongside testosterone to allow the testosterone-to-DHT ratio to be calculated. Document 5-alpha reductase inhibitor therapy and any androgen use. A mass-spectrometry assay is preferred for accuracy at the low concentrations involved, particularly in women and children.
Specimen requirements
Minimum 0.5 mL serum. Separate serum from cells per Access Medical Laboratories protocol. Specimen stable refrigerated; follow Access Medical Laboratories transport guidelines.
What can affect DHT results?
These drugs block conversion of testosterone to DHT, markedly lowering serum DHT as their intended effect. Therapy must be documented, as a low DHT in a treated patient reflects the medication rather than a metabolic disorder.
DHT circulates at low levels, where immunoassays can be unreliable and cross-react with testosterone. Mass-spectrometry methods provide the specificity needed, particularly in women and children, so the assay method affects accuracy.
Because DHT derives from testosterone, low or high testosterone affects DHT, so DHT is interpreted alongside testosterone and as a ratio rather than in isolation.
DHT is largely protein-bound, so changes in sex hormone-binding globulin shift total DHT without necessarily changing bioavailable hormone, complicating interpretation when binding proteins are abnormal.
Much DHT is generated and acts within target tissues, so serum DHT incompletely reflects local androgen exposure in skin, hair follicles, and prostate, limiting how fully it captures androgen-driven processes.
Testosterone therapy and anabolic agents alter substrate availability and can change DHT levels; therapy should be documented for meaningful interpretation.
What do DHT results mean?
Elevated
An elevated DHT reflects increased potent androgen activity and may accompany conditions with androgen excess. In the context of androgenetic alopecia or hirsutism it supports an androgen-driven process, though serum DHT incompletely captures the tissue-level action, so it is interpreted with testosterone and the clinical picture.
Normal
A DHT within the sex-appropriate range, interpreted alongside testosterone, suggests normal potent-androgen production and conversion. Because much DHT action is intracellular, a normal serum value does not fully exclude tissue-level androgen effects in target organs.
Reduced
A low DHT, particularly with a high testosterone-to-DHT ratio, suggests impaired 5-alpha reductase activity, either inherited (5-alpha reductase deficiency) or pharmacological from 5-alpha reductase inhibitor therapy. The therapy history distinguishes these.
Note: DHT circulates at low concentrations, so mass-spectrometry measurement is preferred and immunoassay results may be unreliable, especially in women and children. It must be interpreted alongside testosterone and as the testosterone-to-DHT ratio, and serum levels incompletely reflect tissue androgen exposure. 5-alpha reductase inhibitors markedly lower DHT, so therapy must be documented.
Frequently asked questions
It measures dihydrotestosterone, the most potent endogenous androgen, formed from testosterone by 5-alpha reductase. It assesses potent androgen activity and disorders of androgen metabolism, complementing testosterone measurement.
How to access the DHT test
The DHT reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: June 2, 2026
Last reviewed: June 2, 2026
- Marks LS. 5-alpha-reductase: history and clinical importance. Rev Urol. (2004)
- Swerdloff RS, et al. Dihydrotestosterone: biochemistry, physiology, and clinical implications of elevated blood levels. Endocr Rev. (2017)
- Imperato-McGinley J, Zhu YS. Androgens and male physiology: the syndrome of 5-alpha-reductase-2 deficiency. Mol Cell Endocrinol. (2002)
- Rosner W, et al. Position statement: Utility, limitations, and pitfalls in measuring testosterone and related androgens. J Clin Endocrinol Metab. (2007)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.
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