Age-related differences in serum gonadotropin (FSH and LH), salivary testosterone, and 17-? estradiol levels among Ache Amerindian males of Paraguay

Abstract

Age-related differences in serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), salivary testosterone, and 17-beta estradiol levels are reported for Ache Amerindian males (n = 17; mean age, 37.1 +/- 14.2 SD) of Paraguay in order to explore population variation in patterns of male reproductive senescence in a foraging/agricultural community. Hormone associations were examined to test various hypotheses for age-related differences in hypothalamic-pituitary function. Significant increases in FSH (r = 0.75, P < 0.0005) and LH (r = 0.65, P < 0.01) were noted in association with aging. No significant correlation was observed between morning or evening testosterone and age. Morning and evening estradiol levels were associated with morning and evening testosterone, respectively (morning, r = 0.53, P = 0.05; evening, r = 0.63, P = 0.02). Evening estradiol was also positively associated with LH (r = 0.66, P = 0.02), suggesting testicular production to be an important source of circulating estradiol. Morning estradiol tended to rise with age, but was not significant (r = 0.39, P = 0.15). Anthropometric measurements of height, weight, body mass index, and fat percent did not change significantly with age. In contrast to testosterone, age-related differences in gonadotropin levels may be independent of energetic status, less variant, and more universal among male populations. Implications for gonadotropin function and aging on human male reproductive senescence and life histories are discussed.