Testosterone Blood Test
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Medically reviewed by Kelly Wood, MDMedically reviewed by Kelly Wood, MD
A testosterone test checks how much testosterone is in your blood. Testosterone is the primary reproductive (sex) hormone for people assigned male at birth. People assigned female at birth also have testosterone but at lower amounts.
Before birth, testosterone helps in the development of reproductive organs. During male puberty, testosterone affects things like facial hair, penis growth, libido (sex drive), and sperm production. In females, the hormone impacts sex drive, bone strength, and muscle mass.
Primary healthcare providers, urologists (doctors specialized in the urinary and male reproductive systems), endocrinologists (doctors specialized in hormone-related issues), or fertility specialists may order a testosterone test if you have symptoms—such as low sex drive, fatigue, or infertility—that could indicate whether your testosterone levels are too high or low.
Purpose of the Test
A testosterone test helps providers see if the testosterone levels in your blood are within range of what they should be for your age and sex.
They might order the blood test to investigate puberty-related issues, such as delayed or early puberty. The testing can also be done to monitor your levels if you are taking medication that impacts your testosterone, such as testosterone replacement therapy, or if you are taking testosterone as part of your gender-affirming hormone therapy.
A testosterone blood test can also be performed to help diagnose symptoms that could signal a low or high level of the hormone. Typically, the test is done when there is suspicion of low testosterone in males and high testosterone in females.
Signs of low testosterone levels in men include:
Infertility
Hair loss (especially under the arms and in the pubic area)
Low energy
Low sex drive
Low sperm count
Muscle mass loss
Mood changes
Poor concentration
Signs of high testosterone levels in women include:
Difficulty getting pregnant
Excess face or body hair (hirsutism)
Hair thinning (male-pattern baldness on the scalp)
Irregular menstrual periods
Voice deepening
Enlarged clitoris
For both males and females, early puberty or acne may be signs of high testosterone.
Types of Testosterone Blood Tests
Most testosterone in the blood binds to proteins, delaying its immediate use. Different testosterone tests detect bound (attached to proteins) and unbound (not attached to proteins) levels.
Total Testosterone Test
A total testosterone test measures the combination of bound and unbound forms. However, the test doesn't specify how much testosterone is ready for immediate use. A total testosterone test is common and is usually the first step in diagnosing testosterone-related issues, similar to a screening test.
Free Testosterone Test
A free testosterone test measures the amount of unbound testosterone your body can use. This gives your provider an idea of how much free, or active, testosterone your body has available for factors like sperm production, muscle growth, and bone strength. It is less common than a total testosterone test.
Bioavailable Testosterone Test
A bioavailable test measures both free and loosely bound testosterone. Loosely bound means it’s somewhat available but not as readily available as free testosterone. This test serves as a middle ground between free and total testosterone levels. It is not commonly performed, but it can help diagnose certain issues.
How Does It Work?
A testosterone test is a simple blood draw done at a lab or clinic. Providers typically want you to have the test done between 7-10 in the morning, when testosterone levels are highest.
Before the Test
Check with your healthcare provider if you should fast (not eat or drink anything except water) for a certain amount of time before the test. In some cases, you might need to—especiallly if you are getting other bloodwork done at the same time that may require fasting.
Otherwise, the only thing you will need to do before the test is fill out forms like insurance or privacy paperwork like you would need to do for any other bloodwork.
During the Test
A testosterone blood test takes less than five minutes. You might spend more time at the testing site if other people are ahead of you in line.
During the test, you will be sitting in a chair. A healthcare professional will ask you to put out your arm so they can find a vein to insert the needle. You might feel a quick, slight sting when the needle goes in or out. The steps of a blood draw include:
Placing a wide rubber band on your upper arm to direct blood flow
Cleaning your skin with alcohol
Inserting a tiny needle into your vein
Using a device to draw the blood into a tube
Removing the needle and applying pressure and a bandage
Sending the tube of blood to a laboratory
After the Test
After a blood test, you can usually leave immediately. If needles make you queasy, consider resting a few minutes before driving.
Depending on your results, your provider may order more tests or ask for another testosterone test on a different day. If you're on testosterone therapy, they'll probably check your levels every 6-12 months.
Risks and Precautions
Getting any blood test, including a testosterone test, is generally safe. You might feel a little pinch or notice a bruise where the needle was, but it usually goes away in a short time. If the provider does not perform the blood draw correctly, it could cause more pain or nerve damage, but using the proper technique prevents these problems.
How To Prepare
Before the test, tell your provider if you take any medications or supplements. They can inform you whether you should stop or change your routine for a certain amount of time before the test. Your provider may ask you to fast before the test. The fasting timeframe is typically overnight.
Wear something comfortable with short or loose sleeves. This way, the person drawing the blood has easier access to your arm.
While a blood draw is relatively safe, it can still feel nerve-wracking. You can bring a loved one for support.
Bring a form of identification and your insurance card (if you have one). Many health insurance plans cover at least a portion of the expense, but you can contact them or your provider before the test to make sure. If you need financial assistance for the test, ask your healthcare team about programs or agencies that might help.
Results
It typically takes a few days to receive the results. They may become available to you online in a patient portal. Or, the ordering provider may call you with the results or discuss them with you during a follow-up appointment.
Interpreting Your Results
Testosterone test results show if your levels are low, high, or within normal range. Normal ranges differ based on age and sex. Typically, testosterone is low before puberty and rises afterward, peaking around age 19. After that, testosterone gradually decreases, dropping by about 100 nanograms per deciliter (ng/dL) every decade as you age.
Testosterone reference ranges may vary slightly between labs, but the following are average normal ranges (taken in the morning):
Males under 40: 600-900 ng/dL
Males over 40: 500-800 ng/dL
Females: 15-70 ng/dL
Testosterone results outside of these ranges may be a sign of a number of factors. A healthcare provider will likely need to do more testing to confirm a diagnosis.
Low Testosterone in Males
Diagnosing low testosterone in adult males typically requires two total testosterone levels below 300 ng/dL. Low testosterone may suggest hypogonadism, which is a low or absent function of the gonads (in males, the testes). This leads to inadequate production of sex hormones. About 40% of males over 45 and 50% of males in their 80s have hypogonadism.
Primary hypogonadism happens when the testicles don’t function properly. Several factors can lead to primary hypogonadism, including:
Cancer treatments
Excessive iron in the body (hemochromatosis)
Genetic disorders
Inflammation of the testicles due to conditions like mumps
The natural aging process
Undescended testicles
Secondary hypogonadism occurs when the testicles work properly, but parts of the brain, like the pituitary gland and hypothalamus, don't signal enough testosterone production. Conditions that may cause secondary hypogonadism include:
Genetic disorders
Head trauma
HIV, or human immunodeficiency virus
Hypothalamic dysfunction (when the hypothalamus, which manages hormones, does not work properly)
Infections in the brain, such as meningitis or encephalitis
Pituitary disorders or tumors
Radiation therapy to the brain
Trauma and stress
High Testosterone in Males
High testosterone levels in males may suggest:
Testicular tumors
Disorders of the adrenal glands (small glands that sit on each kidney)
Anabolic steroid use (to gain muscle)
High Testosterone and Behavior
People often link high testosterone in males to aggression. However, researchers debate the connection and think social settings and personalities need to be factored in. Extra testosterone from steroid supplementation (like those for bodybuilding) or medical hormone therapy differs from natural testosterone, further complicating research.
Low Testosterone in Females
It's normal for females to have lower testosterone levels than males. However, levels that are lower than the typical range may signal an issue. Low testosterone in females could indicate disorders of the adrenal gland, pituitary gland, or ovaries.
High Testosterone in Females
In females, abnormal results of a testosterone test is more often due to high levels of the hormone. The following conditions may cause high testosterone in females:
An adrenal or pituitary gland disorder or tumor
A Quick Review
A testosterone blood test measures the amount of testosterone in your blood. Testosterone is the primary sex hormone for males, but females also have small amounts of it. Healthcare providers might order a testosterone test if you have symptoms of low or high testosterone or are taking medications that impact testosterone levels. The test is fast and safe, similar to any other type of bloodwork. If your testosterone blood test shows your levels are out of the normal range for your sex and age, you may need additional testing, which could include a second testosterone test.
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