Aging-related decline in testosterone occurs in men after age 70 years, according to new findings from the Androgens in Men Study. Various comorbidities, medications, and lifestyle factors also affect male testosterone levels.
To identify contributing factors to male testosterone concentrations, investigators obtained raw data from 9 cohort studies involving 21,074 men and 2 cohort studies involving 4075 men aged 17-99 years. Included studies accurately measured circulating total testosterone, dihydrotestosterone, and estradiol levels using mass spectrometry.
After age 70 years, testosterone concentrations declined by 44.7 ng/dL per standard deviation increase, or 15.6 years, even as luteinizing hormone levels increased, which indicated age-related primary testicular impairment, according to meta-analyses.
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“The relative stability of mean testosterone concentration until this age, and the decline after it, raises the question whether a single reference range should be applied across men of all ages,” Bu B. Yeap, MBBS, PhD, of the University of Western Australia, and colleagues wrote in the Annals of Internal Medicine. They noted a proposed reference range for men aged 70 years or older of 184 to 741 ng/dL.
Other factors strongly associated with declining testosterone levels included overweight/obesity, diabetes, and cancer, the investigators reported. Higher body mass index (BMI; above 27.5 kg/m2) was associated with mean testosterone concentrations that were 69.7 ng/dL lower per standarddeviation increase, or 4.1 kg/m2. Having diabetes or cancer was associated with mean testosterone values 40.1 and 41.2 ng/dL lower, respectively.
To a lesser extent, being married, physically active less than 75 minutes per week, a former smoker, and in poor health correlated with declining testosterone levels. These lifestyle factors as well as hypertension, cardiovascular disease, and use of lipid-lowering or psychotropic drugs were each associated with a mean testosterone decrease of 9.8 to 16.4 ng/dL.
Married status might reflect the stresses of family life and its effects on testosterone levels, the investigators suggested.
“Interpretation of individual testosterone measurements should account particularly for age older than 70 years, higher BMI, and the presence of diabetes or cancer,” according to Dr Yeap’s team.
Measuring luteinizing hormone levels can help distinguish if the problem is impaired Leydig cell function or a problem higher up in the hypothalamic-pituitary axis. Sex hormone-binding globulin was directly associated with age and inversely associated with BMI. Free testosterone was not calculated in this study, which is a limitation.
Reference
Marriott RJ, Murray K, Adams RJ, et al. Factors associated with circulating sex hormones in men. Ann Intern Med. Published online August 28, 2023. doi:10.7326/M23-0342
