Vitamin D insufficiency, hemoglobin, and anemia in children with chronic kidney disease

Background: 25-Hydroxyvitamin D (25OHD) deficiency is common in children with chronic kidney disease (CKD). It has been associated with an increased risk for anemia in both healthy US children and in adults with CKD. This association has not been explored in children with CKD. Methods: Children aged 1–16 enrolled in the Chronic Kidney Disease in Children (CKiD) study with mild to moderate kidney dysfunction, and with 25OHD measured at baseline (n = 580), were included in the analysis. The cross-sectional associations between 25OHD and hemoglobin (g/dL) and anemia were assessed. Anemia was defined as hemoglobin < 5th percentile for age and sex. Results: Overall 334 (57.59%) children were vitamin D insufficient/deficient and 137 (23.62%) were anemic. Of those who were vitamin D insufficient/deficient, 95 (28.44%) were anemic. In the overall cohort, the odds of being anemic was 1.9 times higher (95% CI, 1.22–3.04, p < 0.01) in vitamin D insufficient/deficient vs sufficient children, when adjusting for covariates (age, sex, race [black, white, or other], body mass index (BMI), iohexol GFR (iGFR), erythropoietin stimulation agent (ESA) use, iron supplementation use, and underlying cause of CKD). Stratified by race, the odds of being anemic was 2.39 times higher (95% CI, 1.41–4.05, p = 0.001) in vitamin D insufficient/deficient vs vitamin D sufficient white children. The association between vitamin D status and anemia was not significant in black children. Conclusions: The data support our hypothesis that vitamin D insufficiency/deficiency increases the odds of anemia in children with CKD. The effect was strong and significant among white, but not black, children.