Dihydrotestosteron (DHT) Test

The dihydrotestosterone (DHT) test, also known as a DHT blood test, is a blood test that measures the level of dihydrotestosterone in the bloodstream. DHT is a hormone made from testosterone with the help of an enzyme called 5-alpha-reductase. It is an androgen (male sex hormone) that plays an important role in the development of male external genitalia before birth and male physical characteristics such as facial and body hair growth.

Doctors use the DHT test mainly to help diagnose conditions related to abnormal DHT production or function, particularly 5-alpha-reductase deficiency, a condition in which the body cannot produce enough DHT. The DHT test helps assess conditions related to male reproductive development, hormone production, and androgen function, including certain disorders of sex development (DSDs), especially in infants with ambiguous genitalia, boys with delayed puberty, or males with undescended testes.

DHT testing is sometimes used during the investigation of male pattern hair loss (androgenic alopecia) because DHT contributes to hair follicle changes associated with this condition. In some cases, doctors may interpret DHT levels together with testosterone levels and calculate the testosterone-to-DHT ratio, which can help identify 5-alpha-reductase deficiency.

The DHT test may be recommended if a person has symptoms that could be linked to abnormal DHT levels, such as:

• Hair loss, especially on the top or front of the scalp (DHT hair loss).
• Symptoms of prostate enlargement, such as problems passing urine or needing to urinate more frequently.
• Sexual health problems in adults.
• Less facial or body hair than expected.
• Genitals that did not develop normally before birth.

Some people may also need this test because they are more likely to have conditions related to DHT levels. These include:

• Babies born with genitalia that are not distinctly male or female.
• Boys whose puberty is delayed.
• Boys whose testicles have not moved down into the scrotum.
• People being tested for conditions that affect sexual development.
• People taking medicines that lower DHT levels, such as certain treatments for hair loss or an enlarged prostate.

The dihydrotestosterone test is usually advised when investigating specific hormone-related conditions or monitoring treatment, and its frequency depends on the reason for testing.

A dihydrotestosterone test can help doctors investigate conditions that affect sexual development, puberty, hair growth, and prostate health. These include:

• 5-alpha reductase deficiency: A rare genetic condition in which the body cannot make enough DHT. It may cause underdeveloped genitals, undescended testicles, a small prostate, reduced facial hair growth, and delayed or incomplete male development. The testosterone-to-DHT ratio is often used to help diagnose this condition.
• Disorders of sex development (DSD): A group of conditions in which a baby's reproductive organs or genitals do not develop properly before birth. For example, a baby may be born with genitals that are not clearly male or female, a very small penis (micropenis), an opening of the urethra that is not at the tip of the penis (hypospadias), or testicles that have not moved down into the scrotum.
• Delayed puberty in boys: DHT testing, usually together with other hormone tests, may help doctors determine whether problems with hormone production are contributing to puberty starting later than expected.
• Undescended testicles: DHT testing may be used to investigate hormone-related causes when one or both testicles have not moved into the scrotum.
• Male pattern hair loss: A common type of hair loss that usually begins at the front or top of the scalp and gradually worsens over time. DHT is believed to play a role in its development.
• Benign prostatic hyperplasia (enlarged prostate): A condition in which the prostate gland becomes enlarged, often causing symptoms such as difficulty passing urine, a weak urine stream, or frequent urination. DHT plays an important role in prostate growth and may be evaluated as part of the overall assessment.

What to Expect Before the Dihydrotestosterone (DHT) Test

No fasting is required for a standalone Dihydrotestosterone (DHT) test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise Dihydrotestosterone (DHT) levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Dihydrotestosterone (DHT) Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

This test measures one important hormone parameter:

• Dihydrotestosterone: DHT is a hormone made from testosterone that plays an important role in male sexual development, puberty, hair growth, and prostate growth.

Normal DHT levels in males and females can differ significantly with age, as given in the table below:

The interpretation of DHT test results depends on the DHT level, the person's age, sex, symptoms, and the reason for testing, as explained in the table below:

Note:

• DHT test results should always be interpreted together with symptoms, medical history, and other hormone tests.
• A DHT test alone is not enough to diagnose a condition, so doctors may recommend other related hormone tests or genetic testing.

The DHT test is a simple blood test, though it has a few minor risks and some limitations.

Possible Risks of the Test:

The procedure involves a blood draw from a vein, which may cause a slight pinch during needle insertion. Mild pain or bruising at the site can occur in some cases, but these effects are usually minor and go away quickly without any treatment.

Limitations of the Dihydrotestosterone Test:

• DHT hormone levels in the blood do not always reflect the amount of DHT being produced or acting in body tissues.
• DHT test results can vary depending on the laboratory method used.
• Certain medicines, such as finasteride and dutasteride, can lower DHT levels and affect test results.
• The utility of DHT testing is limited for some conditions. For example, DHT levels do not consistently correlate with the severity of male pattern hair loss, and DHT testing is not routinely recommended for diagnosing PCOS.

Along with the DHT test, the tests listed below maybe recommended by doctors to help investigate abnormal DHT levels and related hormone conditions:

• Testosterone test
• Human chorionic gonadotropin (hCG) stimulation test
• Testosterone-to-DHT ratio assessment
• Genetic screening to check for 5-alpha reductase deficiency
• Urine steroid profile