Healthy testosterone (T) and free testosterone (Free T) levels can vary based on age, health status, and other factors. Here is a summary of the findings from the provided sources regarding healthy T and Free T levels:
Total Testosterone (T) Levels
- Total testosterone levels in healthy men typically range from 300 to 1,000 ng/dL. This range is supported by the study on the correlation between vitamin D and testosterone levels in young, healthy men, which provides a baseline for healthy testosterone levels.
- The Baltimore Longitudinal Study of Aging found that total testosterone levels decline with age, with significant decreases observed in men over 60, 70, and 80 years old. The incidence of hypogonadal T levels (below the normal range) increased to about 20% of men over 60, 30% over 70, and 50% over 80 years of age.
Free Testosterone (Free T) Levels
- Free testosterone is the fraction of testosterone not bound to sex hormone-binding globulin (SHBG) and is biologically active. Healthy free testosterone levels are generally considered to be between 50 to 210 pg/mL. This range is consistent with findings from studies that emphasize the importance of free testosterone in diagnosing hypogonadism.
- Similar to total testosterone, free testosterone levels also decline with age. The Baltimore Longitudinal Study of Aging reported an average annual decrease in free testosterone index (free T index = T/SHBG) of -0.0049 nmol T/nmol SHBG per year.
- The European Male Ageing Study highlighted that low free testosterone is associated with hypogonadal signs and symptoms even in men with normal total testosterone levels. This underscores the importance of measuring free testosterone in addition to total testosterone for a more accurate diagnosis of hypogonadism. Additionally, the study on the usefulness of routine assessment of free testosterone for diagnosing functional male hypogonadism found that free testosterone levels significantly correlated with clinical and biochemical parameters of androgen deficiency better than total testosterone levels.
Further Reading:
- Książek, A., Mędraś, M., Zagrodna, A., Słowińska-Lisowska, M., & Lwow, F. (2021). Correlative studies on vitamin D and total, free bioavailable testosterone levels in young, healthy men. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-99571-8
- Harman, S. M., Metter, E. J., Tobin, J. D., Pearson, J., & Blackman, M. R. (2001). Longitudinal Effects of Aging on Serum Total and Free Testosterone Levels in Healthy Men. The Journal of Clinical Endocrinology & Metabolism, 86(2), 724–731. https://doi.org/10.1210/jcem.86.2.7219
- Facondo, P., Di Lodovico, E., Pezzaioli, L. C., Cappelli, C., Ferlin, A., & Delbarba, A. (2022). Usefulness of routine assessment of free testosterone for the diagnosis of functional male hypogonadism. The Aging Male, 25(1), 65–71. https://doi.org/10.1080/13685538.2022.2046727
- Winters, S. J. (2020). SHBG and total testosterone levels in men with adult-onset hypogonadism: what are we overlooking? Clinical Diabetes and Endocrinology, 6(1). https://doi.org/10.1186/s40842-020-00106-3