Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women

Abstract. Brot C, Jorgensen N, Madsen OR, Jensen LB, Sorensen OH (Copenhagen Municipal Hospital, Copenhagen, Denmark). Relationships between bone mineral density, serum vitamin D metabolites and calcium:phosphorus intake in healthy perimenopausal women. J Intern Med 1999; 245: 509–516. Objectives. To determine the relationships between serum vitamin D metabolites, bone mass, and dietary calcium and phosphorus in a cohort of 510 healthy Danish perimenopausal women. Design. A population-based cross-sectional study. Subjects. A total of 510 healthy women aged 45–58 years, with amenorrhoea for 3–24 months. None of the women was using hormone replacement therapy. Measurements. Measurements of total bone mineral content and regional bone mineral density were performed by dual-energy X-ray absorptiometry. Analyses of serum levels of 25-OHD and 1,25-(OH)2D, intact PTH, ionized calcium and phosphate, as well as biochemical markers of bone turnover in blood and urine. Assessment of calcium and phosphorus intake using dietary records. Results. A consistent inverse relationship between serum 1,25-(OH)2D and bone mineral content/density was found in whole-body mineral content (P = 0.001), spine (P = 0.005) and femoral neck (P < 0.05). There was a positive relationship between levels of 1,25-(OH)2D and biochemical bone markers, indicating that high levels of 1,25-(OH)2D are accompanied by increased bone turnover. The dietary calcium:phosphorus ratio was inversely related to serum 1,25-(OH)2D (P = 0.04) and positively related to bone mineral density (P < 0.0005). No relationships could be detected between levels of PTH, serum ionized calcium and phosphate, and serum vitamin D metabolites. Conclusion. Within normal physiological range, elevated levels of 1,25-(OH)2D were associated with decreased bone mineral density and content, reduced calcium:phosphorus ratio in the diet and increased bone turnover.