Vitamin D Deficiency in Cushing’s Disease: Before and After Its Supplementation

Abstract

Background: The primary objective of the study was to assess serum 25-hydroxyvitamin D [25(OH)D] values in patients with Cushing’s disease (CD), compared to controls. The secondary objective was to assess the response to a load of 150,000 U of cholecalciferol. Methods: In 50 patients with active CD and 48 controls, we evaluated the anthropometric and biochemical parameters, in-cluding insulin sensitivity estimation by the homeostatic model of insulin resistance, Matsuda Index and oral disposition index at baseline and in patients with CD also after 6 weeks of cholecalciferol supplementation. Results: At baseline, patients with CD showed a higher frequency of hypovita-minosis deficiency (p = 0.001) and lower serum 25(OH)D (p < 0.001) than the controls. Six weeks after cholecalciferol treatment, patients with CD had increased serum calcium (p = 0.017), 25(OH)D (p < 0.001), ISI-Matsuda (p = 0.035), oral disposition index (p = 0.045) and decreased serum PTH (p = 0.004) and total cholesterol (p = 0.017) values than at baseline. Multivariate analysis showed that mean urinary free cortisol (mUFC) was independently negatively correlated with serum 25(OH)D in CD. Conclusions: Serum 25(OH)D levels are lower in patients with CD compared to the controls. Vitamin D deficiency is correlated with mUFC and values of mUFC > 240 nmol/24 h are associated with hypovitaminosis D. Cholecalciferol supplementation had a positive impact on insulin sensitivity and lipids.