Understanding free testosterone vs total testosterone: A comprehensive guide

Content Health Encyclopedia University of Rochester Medical Center

I guide clients towards optimal physical performance, empowering them to reach their goals through evidence-based exercise programs and personalized coaching. An increase in the Human Growth Hormone (HGH) concentration directly causes an increase in testosterone secretion [16]. This article explores the most common way to discover whether or not you have a free T imbalance and what you can do to remedy the situation. Testosterone deficiency has been detected in 10% – 40% of adult males globally, with age being the most reliable indicator.

This is a new kind of cartography, a mission that may guide us toward better medicine for all. Now Dr. Reina-Campos is investigating how specialized “tissue-resident memory CD8+ T cells” fight prostate cancer. Already, Dr. Reina-Campos has shown the power of spatial transcriptomics in studying T cells that fight pathogens in the gut. He has also developed a promising approach for powering up T cells to better fight tumors. “Spatial transcriptomics enables us to look at hundreds of thousands of cells and thousands of genes in prostate tissues.” By tracking this immune-cell activity, Dr. Reina-Campos can help guide the development of new immunotherapies for prostate cancer, a disease that kills around 35,700 men each year. LJI Assistant Professor Miguel Reina-Campos, Ph.D., specializes in using spatial transcriptomics tools to advance the field of tissue immunology.

In most cases, a test for total testosterone is enough for a doctor to make a diagnosis of low testosterone (Low-T). “This research follows T-cell function all through the monthly cycle, all the way through pregnancy and giving birth—which is when hormone levels really change,” says Dr. Reina-Campos. “This is part of trying to understand the underlying mechanisms of the immune system.”

This indicates that study participants were diverse in their education and occupation. “You don’t need to wait until something feels ‘off’ to check in with a doctor,” says Houman. Instead, you can talk to a healthcare provider if you’re just curious about your hormone health, he says. The information on healthmatters.io is NOT intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. At HealthMatters, we’re committed to maintaining the security and confidentiality of your personal information.

Although present in much lower levels than estrogen and progesterone, testosterone’s balance is crucial for the normal functioning of the female reproductive system. Despite normal total testosterone level results, your doctor may suggest free and bioavailable testosterone blood tests, too, as a deficiency could also cause the adverse effects of overall low testosterone levels [25]. Testing your testosterone levels with your healthcare provider’s guidance can also help you understand how your lifestyle choices may affect this important hormone. Labcorp OnDemand’s Comprehensive Testosterone Test measures total testosterone, free testosterone, albumin and SHBG, providing a complete picture. A healthcare provider may order a free testosterone or total testosterone measurement depending on your symptoms or levels they are trying to check.

“We do sometimes initiate treatment on men with a low calculated free T if the total T is borderline,” Dr. Welliver says. If you are a man and this test cypionate powder reveals your free testosterone is lower than normal, your healthcare provider may prescribe testosterone therapy. To further investigate this link, researchers analyzed data from 897 mother–child pairs, including 458 boys. They measured maternal testosterone at 28 weeks of pregnancy using mass spectrometry and later assessed body composition in the children at age seven using Dual X-ray Absorptiometry (DXA). This advanced imaging technique provided detailed measurements of fat mass and lean body mass.

Free T is not bound to albumin or sex hormone-binding globulin and plays an essential role in muscle growth, sex drive, and mood stability [4]. For instance, a 2021 study in Infection found that among HIV-positive men (for whom low T is very common), only 10.6 percent met diagnosis for hypogonadism based solely on total testosterone levels. But when considering calculated free testosterone, luteinizing hormones, and sex hormone-binding globulin levels, up to 20.2 percent of men would qualify as having subsets of the condition, like overt or compensated hypogonadism. In males aged 19 to 39 years, the harmonized normal range of total testosterone is 264 to 916 ng/dL47, with age-specific median levels ranging from 409 to 478 ng/dL in those aged 20 to 44 years48.

The following table illustrates the range of normal “free” testosterone for men and women by age. Test results may vary depending on your age, gender, health history, and other things. The study, called STEP-HI, involved 129 women 65 and older living in the community who had a recent surgical repair of a hip fracture and experiencing mobility impairment. It is the largest such study of testosterone administration to women following a fracture of the hip and was conducted at UMSOM and seven other clinical sites throughout the country. Dr. Reina-Campos is looking forward to working closely with collaborators, here in San Diego and across the country, to understand how skyrocketing estrogen levels during pregnancy affect T-cell activity in mammary tissue. They interact with other immune cells, and they can sense a huge range of signaling molecules, including testosterone and estrogen. These signaling molecules direct T-cell activity, including antitumor activity.

Free testosterone, which constitutes only about 2-3% of the total testosterone in the body, is not bound to any proteins and is therefore bioavailable and active. This form of testosterone is pivotal in real-time physiological processes, such as muscle building and libido enhancement. Total testosterone, encompassing both the free and protein-bound testosterone, represents the sum total of the hormone in the bloodstream.

Comparing results to age-specific reference ranges allows for a better understanding of hormonal balance and potential underlying issues. Whether it’s addressing symptoms, monitoring hormone replacement therapy, or assessing general health, testing testosterone levels provides valuable information to guide personalized care and optimize overall well-being. Although women have lower testosterone concentrations, this hormone remains critical for various physiological functions, including muscle development, bone density maintenance, and overall metabolic health50(Clark et al., 2018). Resistance exercise has been shown to induce acute increases in testosterone levels in both sexes, potentially contributing to improved musculoskeletal adaptations over time46.