Testosterone (T)

This is a single-marker serum test measuring testosterone. It's also available in saliva.

Ordering The Testosterone Test From ZRT

Testosterone is a steroid hormone that circulates around the body in the blood.

A testosterone levels test measures the amount of testosterone in a blood sample. Testosterone is known as a "male" sex hormone, but females have testosterone in smaller amounts.

In men, testosterone is produced by the testicles and the adrenal gland, controlling the production of sperm and male sex characteristics.

In women, testosterone is produced by the ovaries, the adrenal gland, and other tissues and is involved in overall growth and development.

Testosterone production is controlled by the luteinizing hormone (LH). Testosterone works within a negative feedback loop, so as testosterone levels rise, LH decreases, while increased LH causes decreased testosterone.

Testosterone levels peak in the early morning hours and have the lowest levels in the evening. Levels increase after exercise and decrease with age.

There are Three Types of Testosterone Tests:

Total testosterone test: is the sum of all the testosterone in the blood, bound or not. This is the most common type of test.

Free testosterone test: measures the "active" form of hormone floating in the blood freely without being attached to any molecule. This test is less common but may help diagnose specific medical conditions. High-free testosterone in women and men can impact both health and behavior.

Bioavailable testosterone test: measures free testosterone and testosterone that's loosely attached to a blood protein called albumin. This test isn't commonly done. But, like a free testosterone test, it may help diagnose certain medical conditions.

Which Patients is the Testosterone Test From ZRT Best Used For?

A physician may order the testosterone test if:

• A patient is experiencing low or high testosterone symptom
• Monitor a patient's response to therapy
• Have had an abnormal testosterone test in the past
• A patient is on medications that may affect testosterone levels
• A transgender man taking testosterone for masculinizing hormone therapy (also called gender-affirming hormone therapy)
  

Symptoms of Low Testosterone in Men:

• Low sex drive
• Erectile dysfunction )
• Infertility (difficulty getting someone pregnant)
• Enlarged breasts
• Lack of face or body hair
• Thinning bones or anemia without a known cause
• Loss of muscle mass
  

Symptoms of High Testosterone in Women:

• Abnormal hair growth on the body or face
• Hair loss on the head that may be like male-pattern baldness (hair loss at the temples and balding on the top of the head)
• A voice that gets lower
• Irregular or no menstrual periods
• Infertility
• Acne
  

Children Testosterone Imbalances

Testosterone levels can be checked in children and teens to find out what's causing:

• Early puberty
• Delayed puberty