Understanding free testosterone levels versus total testosterone can be the difference between feeling your best and struggling with unexplained fatigue, low libido, and declining energy. The AMS scale lists 17 symptoms related to low testosterone levels. This may lead to Man B receiving treatment to help supplement the lack of free testosterone in the body, with the aim to treat symptoms they may be experiencing. For example, imagine two men both with a total testosterone of 16 nmol/L (which is within the normal range).3 You could have a "normal" total testosterone level on paper and still feel the classic symptoms of hypogonadism if your free testosterone is too low. Because of these differences, it’s possible to get "normal" or conflicting results depending on which method is used. Since most testosterone in your bloodstream is bound to proteins like SHBG or albumin, only a small fraction is truly "free" and biologically available. Unlike total testosterone, which is relatively straightforward to test, free testosterone is trickier to assess accurately. These levels should be confirmed by early morning blood tests, ideally taken before 10 a.m. Free testosterone is the small percentage of testosterone that's not bound to proteins. Supraphysiologic levels may increase adverse effects without improving the intended therapeutic outcome. Values can shift with assay method, time of day, dosing formulation, time since last dose, illness, and body composition. The AUA uses below 300 ng/dL as a reasonable diagnostic cutoff, but treatment targets are individualized and generally aim for physiologic replacement rather than one universal number (Mulhall et al., Journal of Urology, 2018). That is why Humanaut Health's Hormones program fits best when patients want careful interpretation instead of generic target ranges. A more personalized, proactive partnership should protect against over-treatment just as much as under-treatment. This is especially true in functional hypogonadism, where weight, sleep, metabolic health, and medication effects may influence the entire picture (Corona et al., Andrology, 2020). If you thought testosterone was only important in men, you'd be mistaken. There may be other important functions of this hormone that have not yet been discovered. Testosterone may also help maintain normal mood. The pituitary gland then relays signals to the testes to produce testosterone. Signals sent from the brain to the pituitary gland at the base of the brain control the production of testosterone in men. It is essential to the development of male growth and masculine characteristics. There's more to testosterone than guys behaving badly. It helps men develop during puberty, and as they age, it plays a critical role in helping control fat levels, cholesterol, and glucose levels (1). Not all testosterone in the bloodstream is equally available for your body to use. Check cortisol levels for insights on the body’s stress hormone. It is recommended to consult with a healthcare provider if you have any questions about your results or symptoms. When testosterone levels are typically highest. If you were assigned female at birth (AFAB) and are seeking testosterone testing, consider the Total Testosterone Test for Women. Dr. James R. Staheli is the Medical Director for Broad Health, Hone Health’s affiliated medical practice and a family medicine doctor in Atlanta, Georgia. Every article is rigorously reviewed by medical experts to ensure accuracy. The Edge upholds the highest standards of health journalism. The test also measures several biomarkers, including SHBG, estradiol, luteinizing hormone (LH), and prostate-specific antigen (PSA), and of course, both free and total T. "The lab ranges, however, can vary greatly from highs of 40 to 120 ng/dl." Testosterone levels are measured and reported as nanograms per deciliter (ng/dL). The information on this site should not be used as a substitute for professional medical care or advice. Learn more about laboratory tests, reference ranges, and understanding results. If you have questions about your results, talk to your provider. Levels decline with age, so what's "normal" for a 25-year-old differs from a 55-year-old. Optimal levels for symptom relief are usually in the upper half of the range. His free T is actually 15 pg/mL—better than the first man despite lower total testosterone. Some men with values in the lower-normal range feel fine, while others may be symptomatic. This guide aims to demystify the complexities surrounding free and total testosterone, providing readers with a comprehensive understanding of their impact on health and well-being. Furthermore, understanding testosterone levels is not limited to addressing hormonal imbalances. Total testosterone, encompassing both the free and protein-bound testosterone, represents the sum total of the hormone in the bloodstream. 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. As the "active" form of the hormone, free testosterone can readily bind to receptors and exert its effects on the body. When testosterone is bound to proteins, your tissues are unable to activate testosterone receptors around the body and use the hormone the right way.
