Low Testosterone Diagnosis
How Doctors Diagnose Male Hypogonadism
To diagnose low testosterone (male hypogonadism)—and what’s causing it—your doctor will do several exams and tests. These will help him/her make an accurate diagnosis.
Blood Test to Check Testosterone Levels
A simple blood test can reveal your testosterone level. The normal range is 300 ng/dL to 1,000 ng/dL—remember that testosterone levels fluctuate throughout the day. Because they are normally highest in the morning, your doctor will probably want to do the blood test in the morning.
Your doctor will examine you to look for signs of low testosterone levels. He or she will look at:
- your amount of body hair
- the size of your breasts, testes, scrotum, and penis
- the consistency of your testes and scrotum (are there any lumps?)
- how well you can see to the side (loss of peripheral vision may indicate that you have a pituitary tumor, which can cause low testosterone levels)
The doctor will most likely talk to you about your medical history and your family’s medical history. Discussing your current symptoms will give the doctor a more complete picture of the effects low testosterone is having on you.
The doctor may want to know about:
- your sex drive
- if you’ve experienced erectile dysfunction or impotence
- any current or past illnesses
- any genetic conditions in your family
Low Testosterone Diagnosis
Generally, by combining the results from the blood tests, physical exam, and medical history, the doctor can make a diagnosis of low testosterone (male hypogonadism). To figure out what’s causing your low testosterone, he or she may want to do additional tests, such as:
- MRI or CT scan: If the doctor thinks it could be a pituitary tumor causing male hypogonadism, he or she may order a MRI or CT scan of your brain.
- genetic studies: You may have an inherited condition that’s decreasing your testosterone levels. A genetic test can help the doctor understand your DNA make-up.
- hormone tests: If the doctor suspects that it’s a pituitary abnormality leading to low testosterone, he or she may have you undergo other hormone tests to check your levels of other pituitary hormones.
With an accurate diagnosis of low testosterone, the doctor can start developing a treatment plan.
- Cunningham GR, Matsumoto AM, Swerdloff R, eds. Low Testosterone and Men’s Health (pdf brochure). The Hormone Foundation Web site. http://www.hormone.org/Other/upload/low-testosterone-and-mens-health-bilingual-042710.pdf. Updated March 2010. Accessed October 5, 2011.
- Male hypogonadism: Tests and diagnosis. Mayo Clinic Web site. http://www.mayoclinic.com/health/male-hypogonadism/DS00300/DSECTION=tests%2Dand%2Ddiagnosis. Updated December 9, 2010. Accessed October 5, 2011.
- X-Plain: Low Testosterone Reference Summary. The Patient Education Institute. National Institutes of Health Web site. http://www.nlm.nih.gov/medlineplus/tutorials/lowtestosterone/ur189102.pdf. Updated April 2, 2009. Accessed October 5, 2011.