DHT Test in Australia

What is DHT?

DHT (dihydrotestosterone) is an androgen produced when the enzyme 5-alpha reductase converts testosterone into a more potent form that binds the androgen receptor several times more strongly.

Around 5 to 10 per cent of circulating testosterone is converted to DHT, mostly in tissues that express 5-alpha reductase: skin, hair follicles, the prostate, the liver and the genitals. Once formed, DHT binds the androgen receptor with roughly three to five times testosterone's affinity, and dissociates from it more slowly — which is why a small amount produces a disproportionately large androgenic effect.

Two isoenzymes matter. Type 1 predominates in sebaceous glands and skin generally; type 2 predominates in hair follicles of the scalp and beard, the prostate and the genital skin. This tissue distribution is the reason DHT drives such specific effects: prostate growth, beard and body hair growth, sebum production, and — in genetically susceptible people — miniaturisation of scalp follicles.

DHT is not a villain. In fetal development it is essential for male external genital formation, and people born with 5-alpha reductase deficiency have ambiguous genitalia at birth despite normal testosterone. In adults it contributes to libido and secondary sexual characteristics. The problems attributed to it are problems of tissue sensitivity, not simply of quantity.

That last point is the crux of the testing question, and it is worth stating plainly before you order anything.

Does a DHT blood test predict hair loss?

Not reliably. Androgenetic alopecia is driven mainly by inherited follicular sensitivity to DHT and by locally produced DHT within the scalp, neither of which a serum level measures.

Men with obvious male pattern hair loss frequently have entirely normal serum DHT, and men with high-normal DHT frequently keep a full head of hair into their seventies. The determining variable is how many androgen receptors the follicles express and how strongly they respond, which is inherited — largely, though not exclusively, through variants near the androgen receptor gene on the X chromosome.

There is also a compartment problem. Scalp follicles make their own DHT from testosterone in situ via type 2 5-alpha reductase. Tissue concentrations in balding scalp can be several times those in non-balding scalp of the same person, while their shared serum level is a single number that reflects neither.

So what is a DHT test actually for? Legitimately: investigating suspected 5-alpha reductase deficiency, working up ambiguous androgen results, interpreting an unusual testosterone-to-DHT ratio, and monitoring where a doctor has a specific reason to. Less legitimately: reassurance-seeking before or during hair-loss management, where the number rarely changes what is done.

We would rather tell you that up front than sell you a test that will not answer your question. If hair loss is what brought you here, the bloods that more often change management are ferritin and iron studies, thyroid function, and — depending on the pattern and your sex — androgens more broadly. Our hair loss blood test guide sets those out.

How to test DHT levels

DHT is measured on a morning serum sample, ideally by liquid chromatography–tandem mass spectrometry, and is interpreted alongside total testosterone rather than in isolation.

Assay method matters more for DHT than for most hormones. Immunoassays for DHT cross-react with testosterone, which circulates at 10 to 30 times the concentration — so a small percentage of cross-reactivity produces a large error. Mass spectrometry (LC-MS/MS) separates the two molecules physically and is the reference method. Not every Australian laboratory offers DHT, and those that do may send it to a referral laboratory, which lengthens turnaround.

Because DHT derives from testosterone, it is interpreted as a pair. A low DHT with a normal or high testosterone raises the question of reduced 5-alpha reductase activity; a low DHT with a low testosterone simply reflects low substrate. The ratio is more informative than either number alone, and it is the ratio a clinician will look at.

• Collect between 7am and 10am — DHT follows testosterone's diurnal rhythm.
• Request total testosterone on the same sample; DHT alone is difficult to interpret.
• Ask whether the laboratory uses LC-MS/MS. Immunoassay DHT results should be read cautiously.
• Note any 5-alpha reductase inhibitor, testosterone preparation or topical androgen — all change the result substantially.
• Stop high-dose biotin supplements 48–72 hours before collection.
• Postpone testing during acute illness, and note that DHT is not offered as a rapid-turnaround test everywhere.

Australian reference ranges

Serum DHT is reported in nmol/L and intervals differ substantially between assays, so the laboratory's own range always governs.

Which tests go with a DHT result

DHT is rarely useful alone. These are the tests that make it interpretable, and the ones that more often answer a hair-loss question.

• Testosterone test — the substrate DHT is made from — required to interpret any DHT level.
• Blood tests for hair loss — what an Australian hair-loss work-up actually covers, and in what order.
• Iron studies and ferritin — low ferritin is one of the few genuinely reversible contributors to diffuse hair shedding.
• Thyroid function test — both underactive and overactive thyroid cause diffuse hair loss.
• Oestradiol blood test — part of the androgen–oestrogen picture where testosterone is abnormal.
• Build your own Australian panel — combine DHT with testosterone, SHBG and ferritin in one collection.
• FORM Australian panels — the standard tiers, and which androgen markers each includes.

What high and low DHT can indicate

High DHT usually reflects high testosterone or exogenous androgen exposure; low DHT reflects low testosterone, a 5-alpha reductase inhibitor, or genuinely reduced enzyme activity.

A raised DHT in a man most often accompanies a raised testosterone — from an exogenous androgen, an androgen-secreting source, or occasionally topical testosterone transferring from a partner's skin. In a woman, raised DHT sits within the broader question of hyperandrogenism, most commonly polycystic ovary syndrome, and would be investigated alongside testosterone, SHBG, free androgen index, DHEAS and 17-hydroxyprogesterone.

A low DHT with normal testosterone in an adult raises the possibility of reduced 5-alpha reductase activity, most often pharmacological. Congenital 5-alpha reductase type 2 deficiency is rare, presents at birth or puberty rather than in adulthood, and is diagnosed on the testosterone-to-DHT ratio with genetic confirmation.

In every case, interpretation belongs with a doctor who has your history in front of them. FORM measures and explains; we do not diagnose, prescribe or supply treatment.

Who should consider a DHT test

DHT testing is a targeted test with narrow indications, not a routine part of a hair-loss work-up.

If your actual question is 'why am I losing hair', the more productive tests are usually iron studies and ferritin, thyroid function, a full blood count, and — where the pattern suggests it — an androgen panel. See the hair loss blood test guide for what a standard Australian work-up covers.

• Investigation of an unusual androgen pattern where a doctor has asked for the testosterone-to-DHT ratio.
• Suspected 5-alpha reductase deficiency (usually a paediatric or adolescent question).
• Hirsutism or virilisation in women, as part of a broader androgen panel rather than alone.
• Assessing androgen exposure where there is a history of testosterone or anabolic steroid use.
• Curiosity about your own androgen physiology — a legitimate reason, provided you understand the serum-versus-tissue limitation above.

How DHT testing works with FORM in Australia

You order the test, we issue an Australian pathology request form, and you attend an accredited collection centre in the morning.

• No referral from your own GP is required. Privately requested pathology is arranged under a request from a registered medical practitioner working with our accredited lab partner.
• Collection is a walk-in at Laverty (Healius) pathology centres Australia-wide (NATA / ISO 15189 accredited).
• Results are returned in Australian SI units with a written, plain-English explanation.
• FORM is a diagnostic testing service. We do not prescribe or supply any treatment for hair loss — take your results to your GP or a dermatologist.
• Australian ordering is currently pre-sale. Join the waitlist and we will email you when ordering opens.
• Total testosterone is included with DHT by default, because the ratio is what makes the result interpretable.
• DHT may be referred to a specialist laboratory, so turnaround can be longer than a standard hormone — typically three to seven business days.