Testosterone Blood Test

Testosterone Blood Test

What Is Testosterone?

Testosterone (tess-TOSS-tuh-rone) plays an important role in sexual development. As puberty approaches — usually when kids are between 9 and 14 years old — the pituitary gland releases two hormones: luteinizing hormone (LH) and follicle stimulating hormone (FSH). These hormones work together to trigger the testes to make another hormone: testosterone.

More testosterone leads to a deeper voice, bigger muscles, and body and facial hair. It also helps the testes make sperm.

What Is a Testosterone Test and Why Is It Done?

A testosterone blood test measures the level of the sex hormone testosterone in blood. Doctors might order the test:

• if puberty starts earlier or later than expected
• to see if the testes (testicles), ovaries, pituitary gland, or adrenal glands are working normally
• to look for steroid use

In teens and adults, testosterone levels can help doctors check menstrual (period) problems, fertility (being able to have kids), and sexual function.

Types of Testosterone Tests

There are a few types of testosterone tests:

• Total testosterone: This measures all testosterone in the body, including the amount attached to proteins. Proteins help carry testosterone through the bloodstream.
• Free testosterone: This measures just the testosterone that's not attached to proteins.
• Bioavailable testosterone: This measures the free testosterone and testosterone that’s readily available since it’s only weakly bound to a protein called albumin (al-BYOO-min).

Top Things to Know

• The testosterone blood test measures how much of a hormone called testosterone is in blood.
• This test may be done to see why puberty is early or late, or for other reasons.
• Kids might need to stop taking certain medicines or not eat or drink before the blood test.
• Your doctor can explain what it means if the testosterone level is too high or too low.

How Can I Help My Child Prepare for a Blood Test?

To help kids get ready for a blood test, find out if they need to fast (not eat or drink) or should stop taking medicines before the test. Explain what to expect during the test. If your child is nervous about it, work together on ways to stay calm. Deep breathing or even imagining being in a peaceful place that makes your child feel safe and relaxed can help.

What Do Testosterone Test Results Mean?

Your doctor will explain what the results of the testosterone test mean for your child. “Normal” levels vary based on things like age and gender.

Testosterone could be low because of delayed puberty or high due to precocious (early) puberty.

Results in Males

In males, low testosterone levels (also called “low T”) could mean there’s a problem with the testes, hypothalamus gland, or the pituitary gland. Drinking lots of alcohol can also lower testosterone levels. High testosterone levels might be due to a problem with the testes or adrenal glands.

Results in Females

In females, low testosterone sometimes happens because of problems with the ovaries or adrenal glands, poor nutrition, Turner syndrome, or menopause (when periods stop completely). Ovary and adrenal gland problems can also cause high testosterone. So can certain medicines and Cushing syndrome (too much of the hormone cortisol in the body).

What Else Should I Know?

Sex hormones work closely with each other. So doctors might do a testosterone test along with other blood tests that measure hormones like:

• LH
• FSH
• estradiol
• progesterone (the hormone that prepares the body for pregnancy)

Together, the results can give a more complete picture of sexual development.

If you have questions about the testosterone test or what the results mean, talk to your doctor.