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R Jorde, KH Bonaa and J Sundsfjord

OBJECTIVE: To study associations between serum ionised calcium, serum parathyroid hormone (PTH) and blood pressure. DESIGN: A population based, cross-sectional study was used.Methods: Blood pressure, body mass index, serum ionised calcium and serum PTH were measured in 460 males and 486 females in the Tromso study in 1994/1995. None were on medication for hypertension. The data were analysed with a multiple linear regression model. RESULTS: When looking at subjects with serum ionised calcium<1.39mmol/l, there was a significant negative association (P<0.01) between serum ionised calcium and PTH. There was no association between blood pressure and serum ionised calcium. In both sexes there was a significant positive association between age and serum PTH (P<0.01). For women, but not for men, there was a significant positive association between serum PTH and systolic and diastolic blood pressure (P<0.01). Within each age group there was a difference in both systolic and diastolic blood pressure of 3-10mmHg between the upper and lower serum PTH halves of the female population. Females with hypertension had significantly higher serum PTH levels than the normotensive females (P<0.01). CONCLUSION: Serum PTH is strongly and positively associated with blood pressure in women.

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J Svartberg, M Midtby, KH Bonaa, J Sundsfjord, RM Joakimsen and R Jorde

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 Tromso 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=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=0.016) testosterone and SHBG (P<0.001). Both total and free testosterone were positively associated with tobacco consumption (P<0.001 and P=0.004) and total testosterone was positively associated with coffee consumption (P<0.001). SHBG was positively associated with smoking (P=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.