Objective: To study whether lifestyle factors and/or chronic disease are associated with the age-related decline of total and free testosterone in men, or if these factors might be associated with the variation of total and free testosterone but not with their age-related decline. Design: A population-based, cross-sectional study was used. Methods: Total testosterone and sex hormone binding globulin (SHBG) levels were analyzed and free testosterone levels were calculated in 1563 men participating in the Tromsø study in 1994/1995. Anthropometric characteristics were also measured and two standardized questionnaires completed, including lifestyle factors and medical history. The data were analyzed with multiple linear regression analysis of covariance, and logistic regression. Results: Total and free testosterone were inversely associated (P ¼ 0.001 and P , 0.001), while SHBG was positively associated (P , 0.001) with age. Body mass index (BMI) was inversely associated with total (P , 0.001) and free (P ¼ 0.016) testosterone and SHBG (P , 0.001). Both total and free testosterone were positively associated with tobacco consumption (P , 0.001 and P ¼ 0.004) and total testosterone was positively associated with coffee consumption (P , 0.001). SHBG was positively associated with smoking (P ¼ 0.004) and coffee consumption (P , 0.001). Men who reported having had a stroke or having a cancer diagnosis had lower levels of total testosterone (P , 0.001 and P , 0.01) and free testosterone (P , 0.01). Conclusions: BMI and smoking are independent contributors to the variation of total and free testosterone and SHBG levels, and coffee consumption to the variation of total testosterone and SHBG. Thus, lifestyle factors can have a direct effect on circulating levels of free endogenous sex hormones and to total levels due to the effect on SHBG levels.

The role played by endogenous hormones in many diseases makes it important to understand factors influencing their levels. This study examined the distribution of total and free estradiol, FSH, and dehydroepiandrosterone sulfate (DHEAS) by age and sex and associations of these hormones with body mass index (BMI), lifestyle factors, and chronic diseases. Plasma samples taken from 1555 men and 1952 women 25-84 yr of age in 1994-1995 Tromsø Study were analyzed in 2001. Total estradiol increased with age among men (P < 0.001), with or without adjustment for BMI and lifestyle factors. FSH increased with age both in men (P < 0.001) as well as pre- (P < 0.001) and postmenopausal women (P = 0.01) after similar adjustment, and DHEAS decreased with age in both sexes (P < 0.001). With increasing BMI, free estradiol increased in men (P = 0.004), total and free estradiol increased in postmenopausal women (P < 0.001), and FSH decreased in men (P = 0.03) and postmenopausal women (P < 0.001). Men with chronic diseases had lower levels of DHEAS, compared with healthy men (P < 0.001). Smokers had higher DHEAS levels than nonsmokers. Further studies are needed to confirm these hormonal changes with age and disease.

Background information on how biological factors influence the level of bone turnover markers is crucial in order to make proper use of these measurements. In the present study, which is part of the fourth survey of a general population in Tromsø, Norway, we evaluated the variation in the bone formation markers bone alkaline phosphatase (S-BAP) and osteocalcin (S-OC) in 528 men and 605 women, age 25-74 years. In the Tromsø Study in 1994/5, the whole population above 25 years was initially invited and 7948 individuals attended an extended examination (76.4% of the invited population). The present study population is a random sample of these attendees. The variation with age, gender, height, weight, body mass index and season, and with menopausal status in women, was examined. In men there was a decrease in S-OC up to the age of 56 years with little further change, while S-BAP showed no change with age. Among women, variation in bone markers was mainly observed to change with menopause, with a 41% and 21% increase in the mean level of S-BAP and S-OC, respectively. There was a negative trend in S-OC with body mass index in both men and women. A seasonal change of 20% in the level of both bone markers in men and of S-BAP in postmenopausal women was observed in this region at a far northern latitude. We conclude that, of the factors examined, season and menopausal status must be taken into account when measuring these bone formation markers.