Sex difference of the associations of sex hormone and their related indicators with all-cause mortality.

Plain-language summary

This study asked how sex hormones relate to the risk of dying, separately for men and women. It analyzed 7,294 U.S. adults in the National Health and Nutrition Examination Survey (NHANES, a long-running federal survey that combines interviews with physical exams and bloodwork on a sample built to represent the country). It measured total testosterone, estradiol and SHBG (sex hormone-binding globulin, a protein that binds testosterone in the blood and holds it out of use), then calculated free testosterone (the portion not bound to that protein and available to the body) and the free androgen index (a rough estimate of how much usable testosterone is circulating). In men, higher free testosterone and a higher free androgen index went with lower death rates from any cause, and higher SHBG went with higher death rates. Neither pattern held in women. This is observational, so it shows hormones and survival moving together rather than one causing the other.

Key findings

• Higher free testosterone and free androgen index were linked to lower all-cause mortality in men.
• Higher SHBG was linked to higher all-cause mortality in both sexes, more strongly in men.
• No significant associations were found between these hormone measures and mortality in women.