[Lifestyle] Sociodemographic, lifestyle factors influence testosterone levels in middle-aged men

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“Age, BMI, sociodemographic and lifestyle factors, and prevalent medical conditions show independent and combined influences on sex hormone levels in a large po[CENSORED]tion-based sample of community-dwelling men,” Bu B. Yeap, FRACP, PhD, professor of medicine at the University of Western Australia, and colleagues wrote. “Given the magnitude of their associations, these factors should be considered for potential interventions and when interpreting sex hormone results.” 

 

 

 

Researchers analyzed serum total testosterone and sex hormone-binding globulin levels from a cohort of 208,677 men aged 40 to 69 years participating in the po[CENSORED]tion-based, prospective cohort UK Biobank study from 2006 to 2010. Serum total testosterone was assayed using competitive binding chemiluminescent immunoassay, whereas serum SHBG was assayed with a two-step, sandwich chemiluminescent immunoassay. Researchers calculated free testosterone using the Vermeulen method. Demographic and medication information were obtained through self-reports, and information on prevalent medical conditions came from self-reports, physical exams, blood chemistry and general practice records.

concentration of 11.6 nmol/L, a median SHBG level of 36.9 nmol/L and median calculated free testosterone of 213 pmol/L. Lower serum testosterone and higher SHBG were associated with older age and higher BMI. Calculated free testosterone was lower for older participants and increased with BMI up to 25 kg/m2, at which point it decreased. Both the age and BMI associations were independent of each other.

Mean testosterone was lower for participants who lived with a partner, had South Asian ethnicity and higher educational attainment. Current smokers had higher mean testosterone levels than those who previously smoked or never smoked.

Vegetarians had the lowest mean testosterone concentration, followed by those who ate high amounts of red meat, low amounts of red meat, poultry, fish and no animal products. Testosterone increased with higher levels of physical activity, regardless of alcohol consumption. Mean SBHG levels were lower for men who consumed alcohol, whereas other associations between SHBG and dietary and physical activity patterns were similar to testosterone.

Lower mean testosterone levels

were found for men with prevalent cardiovascular disease, cancer, diabetes, dementia, angina, renal impairment, hypertension and chronic obstructive pulmonary disease compared with those without any of those conditions. Low SHBG was associated with prevalent CVD, diabetes, angina, renal impairment and hypertension. Atrial fibrillation was the only condition associated with higher testosterone and SHBG levels.

After combining several sociodemographic factors, a man of South Asian ethnicity who lived with a partner, ate a low amount of red meat, had a college or university degree and had insufficient physical activity would have a lower mean testosterone level of about 2 nmol/L, according to the researchers. Men who were aged 70 years had a mean testosterone level 0.5 nmol/L lower than those who were aged 50 years, and participants with a BMI of 30 kg/m2 had a mean testosterone concentration 1.5 nmol/L lower than those who had a BMI of 25 kg/m2.

With several factors potentially influencing testosterone levels, researchers said providers should individualize testosterone assessment.

“The combined influences of sociodemographic and lifestyle factors, and medical conditions may provide an informative clinical context for interpreting testosterone and SHBG results in men aged 40 to 69 years,” researchers wrote.