Objective: The effect of vitamin D on bone metabolism is well known. It has recently been shown to be also associated with cardiovascular diseases, obesity, infections, autoimmunity, and cancer. The aim of our study was to evaluate vitamin D deficiency in childhood chronic diseases.

Material and Methods: A total of 438 cases followed-up for vitamin D deficiency/insufficiency (25 OHD level < 30 ng/mL) in our clinic between 2005 and 2011 and who had an additional chronic disorder were evaluated retrospectively.

Results: The mean age of the cases was 12.8±4.6 years and the female/male ratio 1.29 Accompanying disorders included diabetes mellitus, obesity, Turner syndrome, congenital adrenal hyperplasia, myopathy, autoimmune and rheumatic diseases, central nervous system diseases and malignancies. The vitamin D deficiency/insufficiency incidence ranged between 62.5 and 95.0% in the children/adolescents with chronic disease. The mean 25 OHD level was 17±6.6 ng/ml. Hypocalcemia or a similar ion imbalance was not found in any group.

Conclusion: Considering the multisystemic effects of vitamin D, 25 OHD levels should be monitored in chronic diseases in childhood and supplementation provided if necessary. This may lead to an improvement in the course of the underlying disease as well

Keywords: Adolescence, Children, Chronic disease, Vitamin D deficiency