Reviewed By: Dr. Kurt Kloss, MD
Last Reviewed Date: Dec 23, 2018
Last Modified Date: Dec 23, 2018
Published Date: Jul 29, 2017
When to Consider a Testosterone Test
Testosterone is the primary male sex hormone, which means it plays essential roles in the sexual health and function of men. While this is the best-known function of this powerful steroid hormone, it is not the only one. Testosterone also aids in supporting many other aspects of health in both men and women. For that reason, low testosterone levels in the body can have wide-ranging effects, impacting physical, emotional, cognitive and sexual health. A testosterone blood test can aid in diagnosing low testosterone levels, opening the door to treatment that can help alleviate those affects.
What testosterone does in the body
Testosterone influences a variety of functions in the bodies of both men and women. In both sexes, healthy testosterone levels are essential to a healthy sex drive. Men need testosterone for sperm production, and testosterone also helps regulate bone density, muscle mass, metabolism and red blood cell production. This powerful hormone also influences cognitive functions, such as attention and memory, as well as mood and energy levels.
Measures the level of testosterone circulating freely in the body
Measures the total level of testosterone, including the small portion circulating freely in the body
Measures the total level of testosterone in the body
A GUIDE: Testosterone Levels: The Basics
How low testosterone levels can impact health and well-being
Given the influence testosterone has on so many vital bodily functions and systems, low levels of the hormone can cause a broad assortment of symptoms. Men who have deficient testosterone levels often experience some or all of the following:
- Decreased sex drive
- Erectile dysfunction
- Reduced body hair
- Thinning scalp hair
- Bone loss
- Dry and/or thinning skin
- Muscle loss/weakness
- Increased body fat, especially in the chest and abdominal area
- Hot flashes, night sweats
- Decreased energy, motivation, confidence
- Irritability/mood swings
- Poor concentration and/or memory problems
- Sleep disturbances
Women with abnormally low levels of testosterone may experience symptoms that include:
- Decreased energy
- Reduced sex drive
- Bone loss
- Muscle loss/weakness
- Skin changes
- Dry, brittle hair and nails
When to consider a testosterone blood test
If you are experiencing any combination of the symptoms listed above, you should consider having a testosterone blood test. However, it is important to note that many of these symptoms can also be related to other health issues and/or hormonal imbalances, so a thorough physical exam by your healthcare provider is also warranted.
Additionally, low testosterone levels can often occur without obvious symptoms, especially if levels have dropped gradually, making it easier for the body to adjust to the change in levels of hormones. Even without clear symptoms, testosterone deficiency can still have health consequences. Among the most serious of these is:
- Increased risk of osteoporosis, as testosterone deficiency affects bone density
- Increased risk of heart disease, since low testosterone levels have been shown, according to Harvard Men's Health Watch, to increase total cholesterol levels and lead to increases in weight and body fat percentages.
This type of gradual drop often happens with aging. The average man sees a gradual decline in testosterone levels of about 1 to 2 percent per year after age 30. Women also typically see declining testosterone levels with the onset of perimenopause and menopause. While some decline is perfectly normal with aging, for some people, hormone levels drop too low to meet the body's needs for testosterone. For that reason, having occasional testosterone tests to screen for deficient hormone levels may be wise for people age 40 and over to help protect against the potential health effects of undiagnosed and untreated testosterone deficiency.
How testosterone blood testing works
Testosterone levels are most often measured via blood tests. Common tests used to evaluate a patient for low testosterone include:
- Total testosterone tests – The total testosterone blood test measures the overall amount of the hormone circulating in the blood stream, which is then compared to a reference range to determine whether results reflect normal levels. Factors like age, sex, medical status and medications are also considered in evaluating test results. It is important to note that while a total testosterone test can be useful as an initial screening tool, it alone does not provide enough information to either diagnose or rule out low testosterone, since most of the testosterone in the blood is bound to other molecules, making it inactive and unavailable for many uses within the body.
- Free testosterone tests – This blood test measures levels of free testosterone, which refers to hormones that are not bound to other molecules and can be freely used by the body. This is the active form of testosterone that works to influence body processes, and measuring this form of the hormone is essential to an accurate appraisal of hormonal balance.
- Free & Total testosterone tests – This blood test measures both total testosterone levels and the amount of free, unbound testosterone in the bloodstream. Results from these testosterone blood tests will show a patient's personal testosterone levels along with a reference range for comparison. That reference range will reflect the average or normal results for people of the same age and gender.
Treatment for low testosterone
When test results confirm low or deficient testosterone levels, treatment can bring those levels back up to a healthy range. Typically, this will include lifestyle changes to promote hormonal balance, such as dietary changes, exercise and stress management. In many cases, testosterone replacement therapy will also be recommended, which involves supplementation of testosterone levels with hormone-containing medications, and careful, continuous monitoring of hormone levels throughout treatment. Further testing may be done to evaluate the effects of low testosterone and treatment on the body, which may include testing of thyroid function, cholesterol levels, diabetes status and prostate health.
Harvard Men's Health Watch: Testosterone and the heart