Age, Disease, and Changing Sex Hormone Levels in Middle-Aged Men: Results of the Massachusetts Male Aging Study*

Abstract

To evaluate the hypothesis that endocrine profiles change with aging independently of specific disease states, we examined the age trends of 17 major sex hormones, metabolites, and related serum proteins in 2 large groups of adult males drawn from the Massachusetts Male Aging Study, a populationbased cross-sectional survey of men aged 39–70 yr conducted in 1986–89. Group 1 consisted of 415 men who were free of obesity, alcoholism, all prescription medication, prostate problems, and chronic illness (cancer, coronary heart disease, hypertension, diabetes, and ulcer). Group 2 consisted of 1294 men who reported 1 or more of the above conditions. Each age trend was satisfactorily described by a constant percent change per yr between ages 39–70 yr. Free testosterone declined by 1.2%/yr, and albumin-bound testosterone by 1.0%/yr. Sex hormone-binding globulin (SHBG), the major serum carrier of testosterone, increased by 1.2%/yr, with the net effect that total serum testosterone declined more slowly (0.4%/yr) than the free or albumin-bound pools alone. Among the major androgens and metabolites, androstane-3α,17β-diol (androstanediol; 0.8%/yr) and androstanediol glucuronide (0.6%/yr) declined less rapidly than free testosterone, while 5α-dihydrotestosterone remained essentially constant between ages 39–70 yr. Androstenedione declined at 1.3%/yr, a rate comparable to that of free testosterone, while the adrenal androgen dehydroepiandrosterone (3.1%/yr) and its sulfate (2.2%/yr) declined 2–3 times more rapidly. The levels of testosterone, SHBG, and several androgen metabolites followed a parallel course in groups 1 and 2, remaining consistently 10–15% lower in group 2 across the age range of the study. Subgroup analyses suggested that obese subjects might be responsible for much of the group difference in androgen level. Serum concentrations of estrogens and cortisol did not change significantly with age or differ between groups. Of the pituitary gonadotropins, FSH increased at 1.9%/yr, LH increased at 1.3%/yr, and PRL declined at 0.4%/yr, with no significant difference between groups 1 and 2. This study provides epidemiological evidence for some hormone age trends that were previously documented only in smaller, uncontrolled, or questionably representative samples. We found no significant difference between healthy men (group 1) and less healthy men (group 2) with respect to the percent rate of change of any of the serum hormone, metabolite, or protein concentrations measured. The 10–15% lower levels of testosterone, SHBG, and some androgen metabolites in the less healthy men, which were maintained between ages 39–70 yr, might be causes, effects, or mere correlates of disease.