The hormone testosterone (T) is often associated with masculinity. But women’s bodies also make testosterone. Too little testosterone in men or too much in women can indicate serious health problems.

In men, the testicles make testosterone. In women, the ovaries produce the hormone.

Testosterone is responsible for traits such as body hair, muscle mass, and strength. Men with low levels of testosterone might notice a reduction in these traits, while women with too much testosterone might notice an increase in these traits.

You may want to take a testosterone level test if you believe your testosterone levels aren’t within a normal range.

A normal testosterone level range for men is 300 to 1,000 nanograms per deciliter (ng/dL). For women, it’s between 15 and 70 ng/dL. However, it’s also considered normal to have changes in your level of testosterone throughout your life.

Testosterone levels can decrease naturally due to your age or other health conditions. After the age of 40, men’s testosterone levels decrease by an average of at least 1 percent every year. Some symptoms of low testosterone, particularly erectile dysfunction, are commonly seen in men over 40. Low testosterone levels have often been observed in people with obesity, no matter their age.

The most common testosterone-related problem in men is hypogonadism, also called low testosterone.

Your testosterone level may be abnormally low if you have one or more of the following symptoms:

  • decreased sex drive
  • inability to achieve an erection (erectile dysfunction)
  • inability to conceive a child
  • overall tiredness

Women with too much testosterone may grow facial hair, develop a deeper voice, or experience decreased breast size. Too much testosterone in women can also cause acne.

One possible cause of too much testosterone in women is polycystic ovary syndrome (PCOS). PCOS can make it difficult to get pregnant and interfere with menstruation.

Abnormally high or low levels of testosterone in men and women can indicate other serious conditions. High T levels can indicate ovarian or testicular cancer. Low T levels can indicate chronic illness or a problem with the pituitary gland, which releases hormones.

In infant boys and girls, signs of abnormal testosterone levels may be more extreme. Testosterone tests are often ordered for boys and girls who aren’t developing properly or when parents notice delayed puberty.

Boys with low T may grow slowly, with no body hair and poorly developed muscles. Girls with high T may have delayed menstruation or too much body hair. Boys with high T may enter puberty early and robustly.

Sometimes, too much T is the result of a condition known as congenital adrenal hyperplasia (CAH). This testosterone overload can result in males having an abnormally large penis and females having abnormal genitalia at birth.

In some cases, CAH can cause men to have a very deep voice and women to grow facial hair.

CAH can be diagnosed early in infants because it causes dehydration, poor feeding habits, and other symptoms. It can also cause stunted growth, even though someone with this condition may be tall when they’re young.

Getting testosterone levels checked requires a simple blood test. The test is usually performed in the morning, when T levels are highest. Sometimes, the test needs to be retaken to confirm the measurements.

Before the test, your doctor may ask you to stop taking any prescriptions that could affect your testosterone levels. Some medications that can artificially increase your testosterone levels include:

  • steroids (but T levels can fall rapidly after stopping them)
  • barbiturates
  • anticonvulsants
  • androgen or estrogen therapies

Some medications, including opiates, can artificially decrease your testosterone levels. If you’re taking any of the medications above, alert your doctor. They’ll ensure that your testosterone test results are accurate.

Depending on your symptoms, your doctor may also perform a physical examination. If you’re male, your doctor may perform a physical if they notice:

  • a loss of facial hair
  • a loss of height
  • signs of gynecomastia, an abnormal increase in breast tissue size
  • abnormal weight gain

If you’re female, your doctor may perform a physical if they notice:

  • abnormal facial acne
  • abnormal hair growth on your lips or chin (hirsutism)
  • abnormal hair thinning or balding on the head

Testosterone home testing kits are widely available from several companies, such as Progene. They use your saliva to test your hormone levels. After taking the test, you’ll send your sample to a laboratory for testing.

Several studies, including one that sampled nearly 1,500 men between 20 and 90 years old, have confirmed that saliva offers a relatively accurate measurement of testosterone levels. This is especially true when diagnosing male hypogonadism.

Some research suggests salivary testing is not fully reliable, though. They suggest that supplemental tests, such as serum testing, are necessary to ensure that salivary test results are accurate.

Ask your doctor about testosterone tests if you suspect that you have abnormal hormone levels or if you notice developmental issues in your children. A wide range of treatments are available.

The most common treatment for low testosterone is testosterone replacement therapy (TRT). TRT is given as an injection, a skin patch, or a topical gel containing testosterone that replaces the testosterone missing from your body.

Though this treatment is common, TRT is known to have some risks and side effects. They include:

If you’re taking any medications or supplements (such as steroids) that abnormally affect your testosterone levels, your doctor may ask you to stop taking them or suggest an alternative.

Your doctor may also recommend lifestyle changes that can help balance your testosterone levels, such as exercising to build muscle and healthy weight loss through dietary changes.

If you notice any abnormal symptoms, such as hair loss, weight loss, or acne, especially if you’re under 40, you may want to test your testosterone levels. A test can help reveal whether any underlying conditions, health issues, or lifestyle choices are affecting your testosterone production.

In many cases, testosterone levels can vary simply based on your age, diet, drug regime, or even your level of activity. A testosterone test may indicate that your levels are merely a result of the natural aging process or a number of other factors that you can personally regulate.