What is a testosterone levels test?
A testosterone levels test measures the amount of testosterone in a sample of your blood. Testosterone is known as a "male" sex hormone, but females have testosterone in smaller amounts.
Testosterone is made by:
- The testicles (or testes), the part of the male reproductive system that makes sperm
- The ovaries, the part of the female reproductive system that makes eggs
- The adrenal glands, organs on top of each kidney that make several hormones
During male puberty, testosterone causes body hair, muscle growth, and a deepening voice. In adult life, it controls sex drive, maintains muscle mass, and helps make sperm. In females, testosterone is important for the growth of bones and muscles, and healthy organs.
There are different forms of testosterone in your blood that may be measured to help diagnose certain health problems. Most of your testosterone is attached to proteins. The proteins prevent your tissues from using the testosterone right away, which helps control the amount of "active" testosterone in your body. Testosterone that's not attached to proteins is called free testosterone. Free testosterone acts on your tissues.
Three types of blood tests measure these different forms of testosterone:
- A total testosterone test measures free testosterone and testosterone that's attached to proteins. This is the most common type of test.
- A free testosterone test measures only the "active" form of testosterone. This test is less common, but it may be useful for diagnosing certain medical conditions.
- A 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.
Other names: serum testosterone, total testosterone, free testosterone, bioavailable testosterone
What is it used for?
A testosterone levels test may be used with other tests to help:
- Diagnose the cause of symptoms that could be from testosterone levels that are too high or too low
- In children and teens, to find out what's causing:
- Early puberty
- Delayed puberty
Testosterone testing is also used to monitor your health if you:
- Have had an abnormal testosterone test in the past
- Are taking medicine that may affect your testosterone levels
- Are a transgender man taking testosterone for masculinizing hormone therapy (also called gender-affirming hormone therapy)
Why do I need a testosterone levels test?
You may need this test if you have symptoms of abnormal testosterone levels.
For males who have gone through puberty, the test is mostly used for symptoms of low T levels (testosterone levels which are too low). Testosterone levels tend to decrease with age. But other health issues may also cause low T, such as thyroid problems, long-lasting illness, or problems with the testicles.
The symptoms of low T may include:
- Low sex drive
- Erectile disfunction or "ED" (difficulty getting an erection)
- 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
For females, the test is mostly used for symptoms of high T levels, such as:
What happens during a testosterone levels test?
A blood sample for a testosterone test should be taken in the morning between 7 and 10. During these hours, your testosterone levels are typically the highest.
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
In certain cases, you may need to fast (not eat or drink) for several hours before the test. Ask your provider how you should prepare for a testosterone levels test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
Your test results may mean different things depending on which test was done, your age, your symptoms, the results of other tests, and other conditions you may have. So, it's best ask your provider to explain your test results.
A testosterone level test alone can't diagnose any health conditions, but abnormal results with symptoms may be a sign of a health problem.
- In males, low T levels may be caused by different conditions, including:
- In females low T levels are normal, but extremely low levels may be a sign of:
- In males, high T levels may be caused by:
- A tumor in the testicles
- Steroid use
- An adrenal gland disorder, such as congenital adrenal hyperplasia (CAH)
- In females, high T levels may be caused by:
If your results are not normal, it doesn't always mean you have a medical condition that needs treatment. It's normal for testosterone levels to decrease with age. And certain medicines can affect your results. If you have questions about your results, talk to your health care provider.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about a testosterone levels test?
At-home test kits for checking your testosterone levels are available without a prescription. The kits provide everything you need to collect a blood or saliva (spit) sample to send to a lab for testing. Talk with your provider if you think you need to be tested. If you do a home test, share the results with your provider.
- Duca Y, Aversa A, Condorelli RA, Calogero AE, La Vignera S. Substance Abuse and Male Hypogonadism. J Clin Med. 2019 May 22 [cited 2022 May 30];8(5):732. doi: 10.3390/jcm8050732. PMID: 31121993; PMCID: PMC6571549. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6571549/
- Ferrucci L, Maggio M, Bandinelli S, Basaria S, Lauretani F, Ble A, Valenti G, Ershler WB, Guralnik JM, Longo DL. Low testosterone levels and the risk of anemia in older men and women. Arch Intern Med. 2006 Jul 10 [cited 2022 May 30];166(13):1380-8. doi: 10.1001/archinte.166.13.1380. PMID: 16832003; PMCID: PMC2645631. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2645631/
- Hormone Health Network [Internet]. Endocrine Society; c2022. Hypogonadism in Men; [2022 Jan 23; cited 2022 May 30]; [about 9 screens]. Available from: https://www.endocrine.org/patient-engagement/endocrine-library/hypogonadism
- Hormone Health Network [Internet]. Endocrine Society; c2022. Reproductive Hormones; [2022 Jan 23; cited 2022 May 30]; [about 19 screens]. Available from: https://www.endocrine.org/patient-engagement/endocrine-library/hormones-and-endocrine-function/reproductive-hormones
- LabCorp [Internet]. Burlington (NC): Laboratory Corporation of America® Holdings; c2022. Patient Test Information: Testosterone; [cited 2022 May 30]; [about 8 screens]. Available from: https://www.labcorp.com/help/patient-test-info/testosterone
- Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2022. Test ID: TGRP: Testosterone, Total and Free, Serum: Clinical and Interpretive; [cited 2018 Feb 7]; [about 4 screens]. Available from: https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8508
- Oberfield SE, Sopher AB, Gerken AT. Approach to the girl with early onset of pubic hair. J Clin Endocrinol Metab. 2011 Jun [cited 2022 May 30];96(6):1610-22. doi: 10.1210/jc.2011-0225. PMID: 21602454; PMCID: PMC3100750. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100750/
- Roy CN, Snyder PJ, Stephens-Shields AJ, Artz AS, Bhasin S, Cohen HJ, Farrar JT, Gill TM, Zeldow B, Cella D, Barrett-Connor E, Cauley JA, Crandall JP, Cunningham GR, Ensrud KE, Lewis CE, Matsumoto AM, Molitch ME, Pahor M, Swerdloff RS, Cifelli D, Hou X, Resnick SM, Walston JD, Anton S, Basaria S, Diem SJ, Wang C, Schrier SL, Ellenberg SS. Association of Testosterone Levels With Anemia in Older Men: A Controlled Clinical Trial. JAMA Intern Med. 2017 Apr 1[cited 2022 May 30];177(4):480-490. doi: 10.1001/jamainternmed.2016.9540. Erratum in: JAMA Intern Med. 2019 Mar 1;179(3):457. Erratum in: JAMA Intern Med. 2021 May 1;181(5):727. PMID: 28241237; PMCID: PMC5433757. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5433757/
- Testing.com [Internet]. Seattle (WA).: OneCare Media; c2022. Liver Panel; [modified 2021 Nov 9; cited 2022 Mar 15]; [about 12 screens]. Available from: https://www.testing.com/tests/testosterone/
- UF Health: University of Florida Health [Internet]. University of Florida; c2022. Testosterone; [updated 2022 Jan 7; cited 2022 May 30]; [about 4 screens]. Available from: https://ufhealth.org/testosterone
- University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2022. Health Encyclopedia: Total Testosterone; [cited 2022 May 30]; [about 6 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid;=testosterone_total
- UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2022. Testosterone: Test; [updated 2022 Apr 13; cited 2022 May 30]; [about 8 screens]. Available from: https://patient.uwhealth.org/healthwise/article/en-us/hw27307
- WomensHealth.gov [Internet]. Washington DC: Office on Women's Health, U.S. Department of Health and Human Services; Polycystic Ovary Syndrome; [updated 2021 Feb 22; cited 2022 May 30]; [about 13 screens]. Available from: https://www.womenshealth.gov/a-z-topics/polycystic-ovary-syndrome