Testosterone level decline varies in older men

A recent study has noted a broad range of total testosterone levels in older community-dwelling men, with a substantial proportion in a range deemed hypogonadal.

A total of 477 men aged 78‒97 years who participated in the Osteoporotic Fractures in Med study were included in the analysis.

The research team obtained the medical history through clinical visits and questionnaires. They assayed serum sex steroid levels (testosterone, estradiol, estrogen, DHT) using liquid chromatography/mass spectrometry, free testosterone by equilibrium dialysis, and sex hormone binding globulin (SHBG) by radioimmunoassay. SH levels in 215 men were compared to levels obtained 14 years earlier.

The mean total testosterone levels in cross-sectional analyses were 413.9 ng/dL, with significant differences among participants. Total testosterone levels were <275 ng/dL in 21.4 percent of men, and 37.6 percent also had low directly measured free testosterone levels at <6.6 ng/dL.

Notably, total testosterone levels had a modest association with directly measured free testosterone, estradiol, estrone, DHT, and SHBG and had a weak negative association with BMI and smoking.

Longitudinal analyses in 215 participants revealed a decrease in average total testosterone, estradiol, and estrone levels, and an increase in SHBG, but changes were “highly variable.” Among men with total testosterone >275 ng/dL at baseline, 20.5 percent had their levels dipping to <275 ng/dL.

“In longitudinal analyses, although there was considerable interindividual variation, gradual declines in mean total testosterone continued in the 8th through 10th decades of life,” the researchers said.