Age-Related Changes in Plasma Dehydroepiandrosterone Sulphate, Cortisol, Testosterone and Free Testosterone Circadian Rhythms in Adult Men

Abstract

The circadian rhythms of serum luteinizing hormone, follicle-stimulating hormone, testosterone (T), free testosterone (fT), sex hormone-binding globulin (SHBG), oestradiol, cortisol and dehydroepiandrosterone sulphate (DHA-s) have been investigated in 5 normal male adults and 6 elderly men. Circadian rhythms were detected statistically significant (p < 0.05) by population mean cosinor analysis, for T, fT, cortisol and DHA-s in the young group. In the elderly population, serum cortisol showed a clear circadian rhythm, although with some phase modification, whereas DHA-s secretion lost its circadian rhythmicity. This demonstrates that ageing differently affects the two major adrenal functions, glucocorticoid and androgenic; further, the data suggest that an independent adrenal androgen-regulating system could be selectively impaired in the older subjects. In the elderly group the loss of T circadian rhythm was confirmed, but a statistically significant circadian rhythm of fT was recorded. It was characterized by a marked phase advance and not related with the SHBG modifications found in elderly men. This finding leads us to reconsider the role of fT, which appears more sensitive than total T, in studying circadian rhythm of gonadal androgen secretion.

Renin-angiotensin-aldosterone system and the aging kidney

“…Concomitantly, mesangium expands to nearly 12% and some glomerular capillaries suffer obliteration. Renal tubules undergo irregular thickening of their basal membrane, with increasing zones of tubular atrophy and fibrosis [5,11].…”

“…This phenomenon has been attributed to the fact that ammonium ion excretion is less efficient or takes longer to reach its peak in response to an acute acid load in the elderly, though there is no absolute functional deficit in this tubular capability with senescence [5,8,10]. Finally, serum adrenocorticotropic hormone levels in healthy old people are the same as in young people, although its secretion rhythm varies [11]. Besides aging, other important variables which influence the RAAS are family genetics, race and gender.…”

Testosterone levels in men with chronic obstructive pulmonary disease with or without glucocorticoid therapy

“…The intra-assay coefficient of variation was 5.3%. Serum levels of free testosterone (free T) were determined after ultrafiltration by RIA [22]. The detection limit for free T was 50 pM.…”

Prostatic profile, premature ejaculation, erectile function and andropause in an at-risk Mexican population

“…Disorders derived from this decline have been attributed to dysfunctions of the hypothalamichypophysis axis, leading to secondary hypogonadism [18][19][20]. Validated questionnaires are also able to evaluate disorders due to this hormonal decline [21,22].…”