What Is a Testosterone Test?

It checks the level of testosterone in your blood. Your doctor uses it to diagnose conditions caused by too much or too little testosterone. That’s a hormone produced in a man’s testes.

During puberty, testosterone builds a man's muscles, deepens his voice, puts hair on his chest, and makes his penis grow. Throughout a man's life, the hormone also helps produce sperm and keep up his sex drive.

Women make testosterone too, but in smaller amounts. They produce it in their ovaries. It helps maintain hormone balance and regulates other body functions.

What Does the Testosterone Test Measure?

Testosterone travels through your blood in two ways:

  • Attached to the proteins albumin and sex hormone binding globulin (SHBG)
  • Free -- not attached to any proteins

Usually you'll get a total testosterone test. This measures both free and attached testosterone. To diagnose certain conditions, doctors sometimes look only at free testosterone levels.

In males, the testosterone test can help find the reason for sexual problems, like reduced sex drive or erectile dysfunction. If you’re having a hard time getting your partner pregnant, the test can tell if your blood testosterone level is low. It can also screen for problems with the hypothalamus or pituitary gland. This controls how much testosterone your body makes.

In females, this test can find the reason you’re missing periods, not having periods, or having a hard time getting pregnant. Doctors can also use it to diagnose polycystic ovary syndrome (PCOS). That’s a hormone problem that can cause irregular periods and make it hard to get pregnant. A testosterone test can also reveal if you might have a tumor in your ovaries that affects how much of the hormone your body produces.

Why Would I Get This Test?

Your doctor might order it if you have symptoms of low or high testosterone.

Symptoms of low testosterone in men include:

  • Fatigue, depression, or trouble concentrating
  • Hair loss
  • Loss of muscle mass
  • Low sex drive
  • Low sperm count
  • Swollen breasts
  • Trouble getting or keeping an erection
  • Weak bones -- called osteoporosis

In women, they include:

  • Fertility problems
  • Low sex drive
  • Skipped or no menstrual periods
  • Vaginal dryness
  • Weakened bones -- osteoporosis

Symptoms of high testosterone in women include:

  • Acne and oily skin
  • Darkened areas of skin
  • Deep voice
  • Enlarged clitoris
  • Excess hair on the face or body
  • Hair loss on the head (baldness)
  • Skipped or no periods

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What Happens During the Test?

It’s a simple blood test that’s usually done in the morning, when your testosterone levels are highest. Your doctor will take a sample of blood from a vein in your arm or finger. Tell him if you take any drugs or herbal remedies. Some medicines can affect your test results.

What Can Your Results Tell Your Doctor?

They’ll let him know whether you have normal, high, or low testosterone. A normal testosterone level for you will depend on your gender and age.

Normal total testosterone results in adult men:

  • Ages 19 to 49 -- 249 - 836 nanograms per decileter (ng/dL)
  • Ages 50 and older -- 193 - 740 ng/dL

Normal total testosterone results in adult women:

  • Ages 19 to 49 -- 8 - 48 ng/dL
  • Ages 50 and older -- 2 - 41 ng/dL

Depending on your results, you might also need one of these other tests:

  • 17-hydroxyprogesterone. It detects congenital adrenal hyperplasia, which affects your production of hormones.
  • Androstenedione (AD). It checks how well your adrenal glands, ovaries, or testicles work.
  • Biopsy. Your doctor removes a sample of tissue from your testicles to check for cancer.
  • DHEAS. It looks for problems or tumors in your adrenal glands.
  • Estrogens. It measures estrogen levels, and can help diagnose infertility or menopause.
  • Follicle-stimulating hormone (FSH) or luteinizing hormone (LH). They evaluate fertility in women, and puberty in girls.
  • Prolactin. It diagnoses breast discharge, missing periods, infertility, or low sex drive in women.
  • Semen analysis. It measures the number, size, and speed of sperm in a sample.
WebMD Medical Reference Reviewed by William Blahd, MD on March 15, 2017

Sources

SOURCES:

American Association for Clinical Chemistry: "Testosterone: FAQ," "Testosterone: The Test."

Endocrine Society: "What Does Testosterone Do?"

National Heart, Lung, and Blood Institute: "What to Expect With Blood Tests."

National Women's Health Resource Center: "Androgen."

The University of Iowa: "Testosterone, Free and Total, Adult."

University of Rochester Medical Center: "Total Testosterone."

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