Vitamin D in incident nephrotic syndrome: a Midwest Pediatric Nephrology Consortium study.

BACKGROUND: Cross-sectional studies of children with prevalent nephrotic syndrome (NS) have shown 25-vitamin D (25(OH)D) deficiency rates of 20-100 %. Information on 25(OH)D status in incident patients or following remission is limited. This study aimed to assess 25(OH)D status of incident idiopathic NS children at presentation and longitudinally with short-term observation. METHODS: Multicenter longitudinal study of children (2-18 years old) from 14 centers across the Midwest Pediatric Nephrology Consortium with incident idiopathic NS. 25(OH)D levels were assessed at diagnosis and 3 months later. RESULTS: Sixty-one children, median age 5 (3, 11) years, completed baseline visit and 51 completed second visit labs. All 61 (100 %) had 25(OH)D < 20 ng/ml at diagnosis. Twenty-seven (53 %) had 25(OH)D < 20 ng/ml at follow-up. Fourteen (28 %) children were steroid resistant. Univariate analysis showed that children prescribed vitamin D supplements were less likely to have 25(OH)D deficiency at follow-up (OR 0.2, 95 % CI 0.04, 0.6). Steroid response, age, and season did not predict 25(OH)D deficiency. Multivariable linear regression modeling showed higher 25(OH)D levels at follow-up by 13.2 ng/ml (SE 4.6, p < 0.01) in children supplemented with vitamin D. CONCLUSIONS: In this incident idiopathic NS cohort, all children at diagnosis had 25(OH)D deficiency and the majority continued to have a deficiency at 2-4 months. Supplemental vitamin D decreased the odds of 25(OH)D deficiency at follow-up, supporting a role for supplementation in incident NS.