Vitamin D Deficiency in Children with Chronic Kidney Disease

Abstract

Introduction: Vitamin D deficiency leads to defective mineralisation and in Chronic Kidney Disease (CKD) can contribute to renal osteodystrophy. Aim: To compare the serum level of vitamin D in children with CKD as compared to those with normal condition. Materials and Methods: This cross-sectional survey was performed on 68 consecutive children with CKD and 73 sex and age-matched healthy children who were referred to Mofid hospital in Tehran, Iran in 2016. Serum level of vitamin D was measured by immunoassay kits and was then categorised as ≤15 ng/dL (for vitamin D deficiency), 16-30 ng/dL (for vitamin D insufficiency) and >30 ng/dL (for normal condition). Also, the CKD stage was determined by measuring estimated Glomerular Filtration Rate (GFR). Quantitative variables were compared with the t-test, Mann-Whitney test, ANOVA test, or Kruskal-Wallis H test. Qualitative variables were also compared with chi-square test or Fisher’s-exact test. Results: Comparing serum level of vitamin D between CKD and control group showed a significant difference (14.3±9.8 ng/mL versus 18.3±10.9 ng/mL, p<0.001). To investigate relationship between level of vitamin D and stages of CKD, authors determined CKD stages. In CKD group, 5.9% were categorised as Stage I, 20.6% as Stage II, 19.1% as Stage III, 19.1% as Stage IV, and 35.3% as Stage V. In CKD and healthy children, vitamin D deficiency was revealed in 69.1% and 42.5%, and vitamin D insufficiency in 20.6% and 38.4% respectively (p=0.006). Interestingly, the serum level of vitamin D had an inverse association with the CKD stage. By increasing disease stage, the prevalence of vitamin D deficiency gradually increased (p=0.005). Authors found a direct association between CKD stage and serum level of parathormone. Also, the mean level of parathormone was higher in those children with vitamin D deficiency (376.6±296.4 ng/L) as compared to those with vitamin D insufficiency (292.1±259.5 ng/L) and those with normal level of vitamin D (61.4±31.9 ng/L) (p=0.001). Conclusion: Vitamin D deficiency is a common problem among children with CKD compared to control group. In CKD patients vitamin D level is decreased with increasing CKD stage.

Keywords

• chronic renal insufficiency
• paediatric
• parathormone
• renal osteodystrophy