Endocrine Abstracts

Forty-one vitamin D deficient women (aged 26-75 years, mean 56.2, median 57) were treated with Vitamin D3 (50000 IU/week for 1.5 month and 25000 IU/week for another 1.5 month). Before treatment their serum 25(OH)D was 17.3±6.1 ng/ml (mean±SD) and after treatment 37.0±7.5 (P<0.0001). Their HOMA-IR was 2.2±1.1 before and 2.3±1.1 after (P=NS), serum insulin 9.0±4.2 mIU/l before and 9.6±4.5 after (NS), glucose 96.2±8.2 mg/dl before and 97.0±10.0 after (NS), calcium 9.4±0.4 mg/dl before and 9.2±0.5 after (NS), parathyroid hormone (PTH) 82.5±34.2 pg/ml before and 61.4±29.4 after (P<0.0001), and BMI 26.2±3.8 before and 26.3±3.8 (NS) after treatment. The change in HOMA-IR and Insulin after therapy was not uniform in all the women. In 24 women (group I) HOMA-IR increased significantly: from 1.7±0.7 before to 2.4±1.2 after treatment (P<0.0001), and Insulin from 7.2±2.7 to 9.9±5.0 (P=0.0003). In 17 women (group D) HOMA-IR decreased significantly: from 2.9±1.2 to 2.2±1.0 (P<0.0001), and Insulin from 11.7±4.5 to 9.2±3.9 (P<0.0001). HOMA-IR and Insulin were significantly different before treatment (P=0.0002 and P=0.0003) between the two groups I and D, but they were not significantly different after treatment. PTH was not significantly different between the two groups either before or after treatment. The values of some parameters before and after treatment were combined and thus for group I the number of cases became n=48 and for group D n=34. There was a negative significant correlation between the combined values of PTH and 25(OH)D in group D but not in group I. The values of 25(OH)D were not significantly correlated with those of HOMA-IR in both groups. However, there was a significant negative correlation between HOMA-IR and PTH in group I (P=0.04), but a significant positive correlation between HOMA-HR and PTH in group D (P=0.04). Similar were the correlations between 25(OH)D or PTH with Insulin in both groups. Our conclusion is that during vitamin D therapy of vitamin D deficient women there is no direct effect of the serum 25(OH)D level on HOMA-IR or Insulin. The effect of the treatment is mediated by the level of PTH which is significantly correlated with HOMA-IR or Insulin. This conclusion is in keeping with the known from the literature direct effect of PTH on the beta cells of pancreatic islets affecting the secretion of insulin. It seems that the treatment increases the HOMA-IR in women with relatively low baseline values, but it decreases it in those with relatively high baseline HOMA-IR values.