The value and significance of 25(OH) and 1,25(OH) vitamin D serum levels in adult coeliac patients: A review of the literature

Within the wide spectrum of symptoms and alteration of systems that characterizes CeD, several studies indicate a low-level of vitamin D, therefore recent guidelines suggest its evaluation at the time of diagnosis. This review examines the data from existing studies in which vitamin D has been assessed in CeD patients. Our review indicates that most of the studies on vitamin D in adult CeD report a 25 (OH) vitamin D deficiency at diagnosis that disappears when the patient goes on a gluten-free diet, independently of any supplementation. Instead, when the calcitriol, the active 1,25 (OH) vitamin D form, was evaluated, it resulted in the normal range at the time of CeD diagnosis. A strict and lifelong gluten-free diet can help recover vitamin D level without any supplementation.