Predicting Deficiency of Vitamin D in Renal Transplant Recipients in Northern Climates

Background. Renal transplant patients have been shown to have a higher risk of bone disease than the general population. The aim of this study was to examine vitamin D status, a modifiable risk factor in bone disease, in the renal transplant population in a northern climate. Methods. This retrospective observational study included 331 subjects and analyzed demographic, biochemical, and medication information for associations with vitamin D. Results. Of the study population, 45.3% were vitamin D deficient. The percentage of deficient subjects increases to 76.5% if those receiving supplementation are excluded. The mean daily dose of vitamin D was 1275 IU for sufficient patients. For every 1000 IU of vitamin D daily, the risk of deficiency is decreased by 40.3%. Time from transplantation had a significant positive association (P<0.001) in which every year out of transplantation decreased the risk of deficiency by 9.1%. Body mass index had a significant negative association (P=0.012) with vitamin D in which the risk of deficiency increased by 6% for each kilogram per meter squared. Ethnicity was found to be statistically significant on univariate analysis (P=0.034), with white patients having 9.1% decreased risk of deficiency. Conclusion. Despite a high rate of supplementation of vitamin D, close to half of the renal transplant population was still deficient. Those who were receiving over 1000 IU daily were more likely to be vitamin D sufficient. Early supplementation after transplantation along with higher doses for non-white patients or patients with a high body mass index may be warranted for normalization of vitamin D status.