What is a DHT test?
This test measures the amount of dihydrotestosterone (DHT) in your blood. DHT is a hormone made from testosterone. It is produced when an enzyme called 5-alpha-reductase converts testosterone into DHT.
DHT is an androgen, a type of hormone that plays an important role in the development of male sexual characteristics. It is especially important during fetal development and puberty. In adults, DHT also affects the prostate, skin, hair follicles, and other tissues.
DHT is more potent than testosterone at activating androgen receptors. However, testosterone and DHT have different roles in the body.
Other names: dihydrotestosterone test, 5α-dihydrotestosterone test, androstanolone test
What is it used for?
A DHT test may be used to help evaluate conditions related to abnormal androgen activity, including:
5-alpha-reductase deficiency.
This is a rare genetic disorder in which the body has reduced ability to convert testosterone into DHT. It can affect the development of male external genitalia, particularly before birth and during puberty.
Disorders of sexual development.
DHT testing may be used as part of an evaluation when there is atypical development of the external genitalia or an unexplained difference in sexual development.
Androgen-related conditions.
DHT may sometimes be measured when evaluating abnormalities in androgen metabolism or when the relationship between testosterone and DHT is clinically important.
Monitoring 5-alpha-reductase inhibitor treatment.
Medicines such as finasteride and dutasteride inhibit the conversion of testosterone to DHT. DHT testing may be used in selected situations to assess the effect of treatment on DHT production.
Why do I need a DHT test?
Your health care provider may order a DHT test if you have symptoms or findings that suggest an abnormality in androgen metabolism.
In children or adolescents, DHT testing may be considered when there are concerns about:
Abnormal development of the external genitalia
Delayed or atypical puberty
Unexplained differences in sexual development
Suspected 5-alpha-reductase deficiency
In adults, testing may sometimes be considered when investigating:
Abnormal androgen metabolism
Unexpected androgen-related findings
The effect of 5-alpha-reductase inhibitor therapy
Selected disorders involving testosterone and DHT metabolism
DHT testing is not usually a routine test for hair loss or other common androgen-related symptoms. Other tests, such as testosterone, SHBG, and sometimes free testosterone, may be more useful depending on the clinical situation.
What happens during a DHT test?
A health care professional will take a blood sample from a vein in your arm using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
You may feel a little sting when the needle goes in or out. The procedure usually takes less than five minutes.
Will I need to do anything to prepare for this test?
Usually, no special preparation is required for a DHT blood test.
However, follow your health care provider's or laboratory's instructions. Tell your provider about any medicines or hormone treatments you are taking, particularly finasteride or dutasteride, because these medicines can substantially reduce DHT levels.
Are there any risks to this test?
There is very little risk from having a blood test. You may have slight pain, bruising, or tenderness at the site where the needle was inserted. These symptoms usually go away quickly.
What do the results mean?
DHT results must be interpreted using the reference range provided by the laboratory, because concentrations vary according to factors such as age, sex, pubertal stage, clinical condition, and the analytical method used.
Lower-than-normal DHT levels may occur when the conversion of testosterone to DHT is reduced. This can occur with 5-alpha-reductase deficiency or during treatment with medicines that inhibit 5-alpha-reductase, such as finasteride or dutasteride.
In a child with atypical genital development, a low DHT level relative to testosterone may be an important finding. The testosterone-to-DHT ratio may therefore be useful in selected cases when 5-alpha-reductase deficiency is suspected.
Higher-than-normal DHT levels may occur in some conditions involving increased androgen production or metabolism, although an elevated DHT concentration by itself does not establish a specific diagnosis.
Because DHT is strongly affected by its relationship with testosterone and by the patient's clinical condition, your provider may order additional tests, such as:
Total testosterone
Free testosterone
SHBG
Androstenedione
DHEA-S
LH and FSH
17-hydroxyprogesterone
Testosterone/DHT ratio
Your provider will interpret the DHT result together with your symptoms, medical history, physical findings, and other hormone test results.
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