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Cited by 455Hormonal and reproductive studiesGrowth Hormone and Insulin-like Growth FactorsSperm and Testicular Function

Influence of some biological indexes on sex hormone-binding globulin and androgen levels in aging or obese males

Vermeulen, A.·1996·Journal of Clinical Endocrinology & Metabolism
DOI 10.1210/jc.81.5.1821
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Abstract

Several aspects of the regulation of androgen secretion and plasma levels in males remain controversial. Among these, we cite the problem of whether the age-related decrease in testosterone (T) levels is an intrinsic aging phenomenon or is a sequel of previous illness, the mechanisms underlying the increase in sex hormone-binding globulin (SHBG)-binding capacity in aging men and the supranormal capacity observed immediately after a weight-reducing diet, and the role of insulin in the age-associated decrease in dehydroepiandrosterone (sulfate) [DHEA (DHEAS)] levels. To gain further insight into these issues, we investigated the influence of age, smoking, body mass index (BMI), serum albumin, insulin, GH, and insulin-like growth factor I (IGF-I) levels, respectively, on androgen levels and SHBG-binding capacity in a nonobese healthy population (n = 250) as well as in an obese population (n = 50) before and after weight loss. The influence of GH supplementation on SHBG, DHEAS, DHEA, and insulin levels was studied in a small group of men (n = 8) with isolated GH deficiency. In nonobese healthy men, age was inversely correlated with serum levels of all androgens studied (although total T levels stayed relatively stable until age 55 yr) as well as with albumin, GH, and IGF-I levels and positively correlated with BMI, insulin levels, and SHBG-binding capacity. Nevertheless, SHBG levels were significantly negatively correlated with insulin levels (P < 0.001) as well as with mean 24-h GH and IGF-I levels. Among possible confounding factors affecting (free) T [(FT)] levels in healthy men, smoking appeared to be accompanied by higher (F)T levels than those in nonsmokers. BMI increased with age, but although BMI was negatively correlated with T, FT, and SHBG, respectively, the age-dependent decrease in T levels persisted after correction for BMI. Data not corrected for BMI may, nevertheless, overestimate the age-associated decrease in T levels. The albumin concentration decreased with age, and if FT is the feedback regulator of plasma T levels, albumin concentration might be a codeterminant (although, evidently, less important than SHBG) of T levels and contribute to the age-associated decrease in T levels. In any case, albumin concentration is a codeterminant of DHEAS concentration. T, DHEA, and DHEAS levels were significantly correlated, but this correlation disappeared after controlling for age; hence, there is no evidence for an adrenal-gonadal interaction in men. In obese men, T, FT, and SHBG levels were significantly lower than those in the nonobese men and inversely correlated with BMI; DHEAS levels were slightly lower than those in the nonobese controls, but no significant correlation between DHEA or DHEAS, and insulin levels was observed. After a weight-reducing, protein-rich diet, resulting in a mean weight loss of +/- 15 kg, SHBG-binding capacity increased to normal values notwithstanding the fact that the subjects were still obese and that the insulin levels remained higher than those in the nonobese controls. Considering that after weight loss, GH and IGF-I levels remained lower than those in the nonobese controls, that adult men with isolated GH deficiency presented with higher SHBG levels than normal controls, which decreased to normal levels during GH substitution, and that elderly men have elevated SHBG levels notwithstanding high insulin levels, we suggest that the low GH and/or IGF-I levels might play a role in the elevated SHBG levels observed in both elderly males and obese men after a weight-reducing diet. As weight loss did not influence DHEAS levels notwithstanding an important decrease in insulin levels, our data do not support a role of insulin in the regulation of plasma DHEAS levels.

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Authors
Vermeulen, A.
Affiliations
Ghent University Hospital (BE)
ORCID
Vermeulen, A.
Venue
Journal of Clinical Endocrinology & Metabolism
Publisher
The Endocrine Society
Published
1996-05-01
Volume
81
Issue
5
Pages
1821-1826
ISSN
0021-972X (ISSN-L)
DOI
10.1210/jc.81.5.1821
OpenAlex
W1985489419
Cited by
455
References
21
Citations by year
2026: 1 · 2025: 5 · 2024: 7 · 2023: 3 · 2022: 12 · 2021: 7 · 2020: 11 · 2019: 8 · 2018: 6 · 2017: 12 · 2016: 6 · 2015: 14 · 2014: 12 · 2013: 19 · 2012: 23
FWCI
7.79
Type
journal article
Language
en
Open access
closed
Locations
  • The Journal of Clinical Endocrinology & Metabolism (publishedVersion)
  • PubMed (publishedVersion)
  • Ghent University Academic Bibliography (Ghent University) (submittedVersion)
Topics
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Hormonal and reproductive studies
  • Health Sciences › Medicine › Endocrinology, Diabetes and Metabolism › Growth Hormone and Insulin-like Growth Factors
  • Health Sciences › Medicine › Reproductive Medicine › Sperm and Testicular Function
Keywords
sex hormone-binding globulin, androgens, older men, obesity, testosterone, free testosterone, dehydroepiandrosterone sulfate, insulin, insulin-like growth factor I, growth hormone, body mass index, smoking, serum albumin, weight loss, weight loss diet, GH deficiency, androgen regulation, healthy men, healthy women, menopausal women
MeSH terms
Adult, Aged, Aged, 80 and over, Aging, Androgens, Dehydroepiandrosterone, Humans, Insulin, Insulin-Like Growth Factor I, Male, Middle Aged, Obesity, Serum Albumin, Sex Hormone-Binding Globulin, Smoking, Growth Hormone, Testosterone, Body Mass Index, Dehydroepiandrosterone Sulfate

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