Bone Abstracts

Objectives: To assess the effects of short-term vitamin D supplementation on bone metabolism, glycaemic status and immune function in vitamin D deficient children.

Method: Treatment with daily 5000 IU cholecalciferol supplementation for 6 weeks. At baseline and end of treatment serum 25 hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH), alkaline phosphatase (ALP), serum collagen type 1 cross-linked C-telopeptide (CTX), serum calcium, HbA1c, sex hormone-binding globulin (SHBG), fasting insulin, fasting blood glucose, and homeostasis model assessment index–estimated insulin resistance (HOMA-IR) were measured. Leukocyte subsets analysis was performed for (T/B cells) and T regulatory cells. Fifteen different cytokines/chemokine (IL2, IL4, IL5, IL6, IL8, IL10, IL12, IL17, EOTAXIN, MIP-1b, IP-10, TNFα, INFγ, RANTES, and MCP1) were measured.

Results: 25 children enrolled in the study with median (range) age 5 years (10 months, 9.5 years). Serum 25(OH)D concentration increased from 29 (14, 125) mmol/l to 115 (37, 225) mmol/l at 6 weeks, P<0.0001. Serum PTH concentration decreased from 5.5 (3.6, 134) pmol/l to 3.9 (1.9, 6.8) pmol/l at 6 weeks, P<0.0001. In 17 patients whose glucose, insulin and HOMA-IR data were measured, serum 25(OH)D increased significantly from 27 (14, 125) mmol/l to 110 (37, 225) mmol/l, P<0.001. HOMA-IR fell from 1.84 (0.16, 20.29) to 1.59 (0.07, 12.5) and insulin secretion decreased from 11.1 (2.46, 99.2) μIU/ml to 8.1 (1.8, 66.6) μIU/ml. However, this reduction was not statistically significant (P=0.5 and P=0.5 respectively). There was a significant correlation between fasting insulin and both PTH and alkaline phosphatase at base line (r=−0.6, P=0.0009 and r=−0.5, P=0.02 respectively). No changes were observed in glucose, HbA1c and SHBG. Nineteen patients had sufficient blood available for cytokine assay and eight patients underwent flow cytometry for leukocyte subsets (T/B cells) and T regulatory cells with no significant change over time.

Conclusion: Supplementation of daily 5000 IU cholecalciferol has a significant effect in markers of bone turnover. PTH but not vitamin D level at baseline was found to be significantly associated with fasting insulin levels. There was no evidence of an effect of treatment with vitamin D on immune function.

Disclosure: The authors declared no competing interests.