Prevalence of 25(OH) Vitamin D Insufficiency and Deficiency in Pediatric Patients on Chronic Dialysis

Abstract

25(OH) Vitamin D [25(OH)D] is the major circulating form of vitamin D and the parameter used to reflect vitamin D status. Patients with chronic kidney disease (CKD) are likely to have low levels of 25(OH)D, and recent observations have linked suboptimal vitamin D status with adverse cardiovascular outcomes, inflammation, insulin resistance, and the rate of progression of renal insufficiency. Little is known about the magnitude of vitamin D deficiency in pediatric patients with stage 5 CKD on chronic dialysis. The aim of the present cross-sectional study was to assess the prevalence of abnormal vitamin D status in children on chronic dialysis. Serum 25(OH)D, 1,25(OH)2 vitamin D [1,25(OH)2D], calcium, phosphorus, and parathyroid hormone (PTH) were evaluated in 59 pediatric patients on chronic dialysis. Weekly renal Kt/V and creatinine clearance (CCr) were evaluated as parameters reflecting residual renal function. In these patients, serum 25(OH)D concentrations less than 10 ng/mL were considered deficiency and concentrations of 10 - 30 ng/mL were considered insufficiency. Of the 59 pediatric patients (mean age: 14.4 ± 5.1 years), 51 (86.4%) were on peritoneal dialysis (PD), and 8 (13.6%) were on hemodialysis. Vitamin D deficiency was found in 32.2% of the patients (n = 19), and vitamin D insufficiency, in 50.8% (n = 30). Patients with serum 25(OH)D concentrations less than 30 ng/mL were older than those with normal 25(OH)D concentrations (15.4 ± 4.5 years vs 9.2 ± 5.1 years, p = 0.000). Patients with 25(OH) D concentrations less than 30 ng/mL had higher PTH levels than did those with normal 25(OH)D concentrations (349.5 ± 318.3 pg/mL vs 142.5 ± 116.9 pg/mL, p = 0.001). In the univariate analysis, there was no correlation between serum 25(OH)D and serum 1,25(OH)2D (r = 0.242, p = 0.064), calcium (r = 0.108, p = 0.415), phosphorus (r = -0.050, p = 0.706), or body mass index (r = -0.046, p = 0.729). In PD patients, serum 25(OH)D was positively correlated with weekly renal Kt/V (r = 0.385, p = 0.005) and CCr (r = 0.443, p = 0.001). In addition, serum 25(OH)D and serum albumin were positively correlated (r = 0.297, p = 0.035) in the PD patients. The present study found a high prevalence of 25(OH)D deficiency and insufficiency in children on chronic dialysis. Serum 25(OH)D was associated with residual renal function in children on PD. Further studies to evaluate the consequences of vitamin D deficiency and the impact of therapeutic interventions are needed in pediatric CKD patients.