engleski

Vitamin D and parathyroid hormone in relation to bone health in Croatian women

Purpose: Bone mineral density (BMD) is known to be affected by serum 25-hydroxyvitamin D (25(OH)D) and intact parathyroid hormone (iPTH) levels. Our objective was to analyze the association between serum 25(OH)D and iPTH and their mutual regulatory mechanisms on BMD in women with 25(OH)D deficiency. We also attempted to establish a threshold for the serum 25(OH)D below which the serum iPTH increases. Methods: The participants were 400 community dwelling women (mean age 46.9 ± 15.5 years) recruited from the local communities. BMD was measured by dual energy x-ray absorptiometry and 25(OH)D, iPTH, calcium, phosphorus, alkaline phosphatase, osteocalcin, C- telopeptide (CTX) were analyzed from the fasting blood samples. Multivariate regression models were used to investigate the relationships among serum 25(OH)D, iPTH and BMD. Results: Serum iPTH increased when 25(OH)D concentrations were below 46.9 nmol/l. Severe 25(OH)D deficiency (<25 nmol/l) was found in 7% of the participants and was associated with significantly higher iPTH compared to participants with serum 25(OH)D >25 nmol/l. BMD was negatively associated with iPTH only in the group with severe 25(OH)D deficiency. However, BMD was not significantly lower in the participants with severe 25(OH)D deficiency compared to those with mild deficiency or with adequate status. Conclusions: Our results did not show a negative impact of iPTH on BMD or bone turnover markers in women with severe 25(OH)D deficiency. This could be explained by the relatively young age of our participants in whom the unfavorable effect of 25(OH)D deficiency on bone might not yet have appeared.

vitamin D ; PTH ; bone mineral density ; C-telopeptide ; osteocalcin

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