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Determinants of serum calcium in men and women. The Tromsø Study
R Jorde1, J Sundsfjord, K H Bønaa
1Department of Medicine, University Hospital of Northern Norway, Tromsø, Norway. rolf.jorde@unn.no
Insights
Serum calcium levels vary with age and sex, showing positive links to body mass index and coffee intake. Other lifestyle factors like alcohol and smoking also influence levels, though biological significance remains uncertain.
Area of Science:
- Cardiovascular disease research
- Human physiology
- Nutritional epidemiology
Background:
- Serum calcium levels are linked to blood pressure and metabolic syndrome, key cardiovascular disease risk factors.
- Understanding determinants of serum calcium is crucial for cardiovascular health.
- Previous research has not fully elucidated the lifestyle and demographic factors influencing serum calcium.
Purpose of the Study:
- To investigate the associations between serum calcium levels and various lifestyle and demographic factors.
- To identify potential modifiable determinants of serum calcium.
- To assess the influence of age, sex, diet, and lifestyle on serum calcium concentrations.
Main Methods:
- Cross-sectional analysis of 27,159 participants from the Tromsø health survey (1994-1995).
- Measurements included serum calcium, body mass index (BMI), coffee consumption, physical activity, alcohol intake, and cigarette smoking.
- Multiple regression models were used to analyze associations, adjusting for potential confounders.
Main Results:
- Serum calcium levels showed age-related declines in males and sex-specific patterns around menopause in females.
- Positive associations were observed between serum calcium and BMI and coffee consumption in both sexes.
- In females, alcohol consumption was negatively associated, and smoking positively associated with serum calcium.
Conclusions:
- Serum calcium levels are influenced by age, sex, BMI, and lifestyle factors like coffee consumption, alcohol intake, and smoking.
- While associations exist, the small effect sizes suggest limited biological significance for most observed factors.
- Further research is needed to clarify the clinical implications of these associations and the role of factors like serum albumin.
Abstract:
The level of serum calcium appears to be associated with blood pressure and metabolic risk factors for cardiovascular disease. Determinants of serum calcium may therefore be of interest. In a health survey in Tromsø in 1994-1995, 27,159 subjects were examined. The survey included measurements of serum calcium and questionnaires on diet and lifestyle factors. In males mean serum calcium declined from 2.41 mmol/l for those in their 20s to 2.34 mmol/l for those in their 80s. In females mean serum calcium was stable at a level of 2.35 mmol/l before the menopause, and thereafter reached a plateau of 2.39 mmol/l. In both sexes serum calcium showed a positive association with body mass index (BMI) and coffee consumption that persisted after correcting for other variables in a multiple regression model (p < 0.05). Physical activity had no significant association with serum calcium. In females alcohol consumption was negatively, and cigarette smoking positively associated with serum calcium (p < 0.01). No significant effect on the serum calcium levels was found for the intake of calcium or vitamin D, except for males with a calcium intake below 200 mg/day. Some of the observed effects, like the variation with age, may partly be explained by alterations in levels of serum albumin to which approximately 40% of circulating calcium is bound and which was not adjusted for in this study, whereas that is hardly the case for the association with BMI and coffee consumption. However, none of these factors could affect the serum calcium level more than 0.02 mmol/l, and the biological significance of the observed associations questionable.