Endocrine Abstracts

Introduction: It is unknown what causes ageing men to have lower testosterone levels and how those levels relate to risk factors. Less research has been done on the health of ageing males than on postmenopausal women.

Objective: The aim was to look into how men-aging lifestyles and health related to their levels of reproductive hormones.

Method: A prospective cohort study in Indian men included 320 community-dwelling men between the ages of 41 and 78 for this baseline cross-sectional survey. Equal numbers of men were chosen from the general population to represent each of the four age groups: 41-48, 51-58, 61-68, and 71-78 year. As long as the person could respond to the mail invitation and give written informed consent, there were no particular exclusion criteria. As soon as the null hypothesis could be rejected at the 0.04 (two-tailed) level, the results were deemed statistically significant. SAS proc mixed and STATA version 9.2 were used for all data analyses.

Results: Different forms of changed function were linked to four predictors, including: 1) Older age: decreased free T (FT; 3.11 pmol/liter/yr, P<0.002) and elevated LH, suggesting the reduced testicular function, 2) Obesity: lower total T (TT; 2.31 nmol/liter) and FT (17.61 pmol/liter) for body mass index (BMI; 24 to 29 kg/m2); lower TT (5.08 nmol/liter) and FT (52.71 pmol/liter) for BMI 29 kg/m2 or above (P<0.002-0.02, referent: BMI 24 kg/m2); 3) comorbidity: greater LH in older men but unchanged TT (0.81 nmol/liter, P<0.02) in younger men; 4. Smoking: higher SHBG (5.95 nmol/liter, P<0.002) and LH (0.76 U/liter, P<0.02) with increased TT (1.30 nmol/liter, P<0.002) but not FT, consistent with a resetting of T-LH-negative feedback due to raised SHBG.

Conclusions: Age-related testicular dysfunction is accompanied by complex multiple abnormalities in the hypothalamic-pituitary-testicular axis function in ageing men. Varied risk variables have different relationships with these changes. Some risk factors contribute to the T decrease independently of age, whereas others interact with it. These possibly modifiable risk variables point to potential preventive steps that men can take to preserve T as they age.