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Willem de Ronde, Albert Hofman, Huibert A P Pols and Frank H de Jong

Objective: The origin of oestrogens in men is only partly understood. From infusion studies with radioactively labelled hormones, we know that oestradiol (E2) and oestrone (E1) are either directly secreted by the testes and adrenal glands or peripherally produced from testicular or adrenal androgens.

Design and methods: We determined E2, E1, androstenedione, testosterone and dehydroepiandroster-one sulphate (DHEAS) in 292 elderly men and 367 postmenopausal women. We considered post-menopausal women as men without testes, assuming that the postmenopausal ovary is not endocrinologically active and that the testes do not contribute to circulating levels of DHEAS. Subjects were stratified by DHEAS levels to adjust for differences in DHEAS levels between sexes. For men and women separately, mean levels of E2, E1, androstenedione and testosterone were calculated per DHEAS stratum. The relative direct and indirect contributions of the testes to steroid levels in men were calculated by the formula [(Cm −Cf)/Cm] × 100%, in fwhich Cm and Cf represent the mean concentrations of the steroid in men and women respectively.

Results: The relative contributions (%) of the testes to hormone levels per DHEAS stratum (<2, 2–4, 4–6 and >6 μmol/l) respectively were, for E2, 72%, 60%, 52% and 44%; for E1, 54%, 47%, 35% and 34%; for androstenedione, 14%, 4%, 12% and 0%; and, for testosterone, 88%, 88%, 87% and 83%.

Conclusions: We conclude that in elderly men dependent on DHEAS levels, 44–72% of E2 and 34–54% of E1 originate directly or indirectly from the testes.

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I Rietveld, A Hofman, H A P Pols, C M van Duijn, S W J Lamberts and J A M J L Janssen

Objective: Microalbuminuria (MA) is related to cardiovascular disease both in diabetic patients and non-diabetic subjects.

Design: We investigated whether a polymorphism near the promoter region of the IGF-I gene was related to the development of MA.

Methods: For this study, 1069 participants of the Rotterdam study were selected (440 participants with an abnormal glucose tolerance (AGT), 220 participants with type 2 diabetes and 254 subjects with pre-diabetes, and 595 subjects with a normal glucose tolerance (NGT).

Results: 787 subjects were carriers of the wild type IGF-I genotype (73.6%) and 282 subjects were variant carriers (26.4%) of this IGF-I gene polymorphism. Compared to subjects with NGT the risk for microalbuminuria was higher (Odds Ratio (OR): 3.1 (95% CI: 1.2–7.7); P = 0.02) in variant carriers with AGT than in carriers of the wild type of this IGF-I gene polymorphism (OR: 2.2 (95% CI: 1.2–4.0); P = 0.009). Compared with wild type carriers with AGT, the relative risk for MA was unadjusted and non-significantly increased in variant carriers with AGT (1.6; 95% CI: 0.8–2.9). However, after adjustment for possible confounding factors (age, gender, mean blood pressure, fasting insulin, fasting glucose and smoking) this risk became significant (OR: RR 2.1; 95% CI:1.1–4.4; P = 0.04).

Conclusions: In subjects with AGT, a higher risk for MA was observed in variant carriers than in carriers of the wild type genotype of this IGF-I gene polymorphism. Since MA is primarily associated with cardiovascular disease in subjects with AGT, our study suggests that variant carriers have a higher risk for cardiovascular disease than carriers of the wild type when they develop an AGT.

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Stephanie C E Schuit, Frank H de Jong, Lisette Stolk, W Nadia H Koek, Joyce B J van Meurs, Mariette W C J Schoofs, M Carola Zillikens, Albert Hofman, Johannes P T M van Leeuwen, Huibert A P Pols and André G Uitterlinden

Objective: Postmenopausal estradiol (E2) levels vary widely between individuals and this variation is an important determinant of diseases such as osteoporosis. It has been suggested that the estrogen receptor alpha (ESR1) gene may influence peripheral E2 levels, but the role of common sequence variations in the ESR1 gene is unclear.

Methods: In 631 postmenopausal women and 528 men from the Rotterdam Study, a population-based, prospective cohort study of individuals aged 55 years and over, ESR1 PvuII-XbaI haplotypes were determined and correlated with plasma E2 levels.

Results: In women, haplotype 1 (T-A) was significantly associated with an allele-dose-dependent decrease in E2. After adjusting for age, body mass index, years since menopause and testosterone levels, plasma E2 levels decreased by 1.90 pmol/l per allele copy of this haplotype (P < 0.05). Extreme genotypes, representing 23 and 27% of the population, varied by 3.93 pmol/l. No association with plasma testosterone was observed. In a subset of 446 women, no association of genotype with plasma concentrations of dehydroepiandrosterone sulfate, androstenedione or estrone was seen. In men, none of the sex hormone levels was associated with the ESR1 PvuII-XbaI haplotypes.

Conclusion: We have demonstrated a role for genetic variations in the ESR1 gene in determining post-menopausal E2 levels in women.