Vitamin D Supplementation: Not So Simple in Sarcoidosis

IntroductionAmericans are increasingly receiving vitamin D supplementation, often based on low-measured 25-hydroxy-vitamin D (25-OH-vit D). In sarcoidosis, there is often increased metabolism of 25-OH-vit D to 1,25-dihydroxy-vitamin D (1,25-OH-vit D), so 25-OH-vit D may remain low, despite high levels of 1,25-OH-vit D. In such cases, vitamin D supplementation may lead to hypercalcemia.MethodsWe randomly selected 196 patients with sarcoidosis who received at least 1 prescription of vitamin D between 2005 and 2011 and 196 control patients. Primary outcome was the incidence of hypercalcemia during the 2 years following the vitamin D prescription. A secondary outcome was the proportion of patients who had received vitamin D prescriptions and who had adequate blood work performed before the prescription.ResultsThe 25-OH-vit D and 1,25-OH-vit D levels were measured in only 70% and 23%, respectively, of those receiving supplementation. Hypercalcemia was noted more frequently in the group that received vitamin D (42.3%) as compared with the nonsupplemented group (18.3%), P < 0.0001. Patients who received a vitamin D prescription developed moderate and severe hypercalcemia more frequently (12.8%) as compared to the group that did not receive vitamin D (3.6%), P = 0.001. In multivariate analysis, having a prescription for vitamin D increased the risk of developing hypercalcemia to approximately 2-fold. The risk of developing hypercalcemia (odds ratio = 4.1) was increased with renal failure.ConclusionsOur study demonstrates that a substantial proportion of patients with sarcoidosis who receive vitamin D are not getting appropriate pretesting. This increases their risk for developing hypercalcemia.