Vitamin D Status in Children with Chronic Kidney Disease

BACKGROUND: Vitamin D deficiency is a major contributor to secondary hyperparathyroidism in patients with chronic kidney disease (CKD). The objective of this study was to determine the vitamin D status in children with CKD. METHODS: This cross-sectional study was conducted in the Department of Pediatric Nephrology, National Institute of Child Health (NICH), Karachi from January 2013 to December 2013. Ninety patients aged 3 months to 17 years with CKD were included. CKD was categorized into 5 stages based on glomerular filtration rate (GFR) and stage 4 and 5 were labeled as advanced CKD. Patients on 25-hyroxy vitamin D (25OHD) therapy were excluded. Radioimmunoassay was used to measure 25OHD level and it was defined as sufficient (>30-80 ng/ml), insufficient (16-30), mild to moderate deficiency (5-15 ng/ml) and severe deficiency (< 5ng/ml). Data including age, gender, blood urea (U), serum creatinine (Cr), GFR, CKD-stage, etiology, serum calcium (Ca), serum phosphorus (P), serum alkaline phosphatase (ALP), serum parathyroid hormone (PTH) and serum 25OHD level were collected and analyzed by SPSS using descriptive statistics. RESULTS: Of the 90 patients, 55 (61.1%) were males. Mean age was 7.4 +/- 4.6 years. Mean U, Cr and GFR were 113.5 +/- 82.0 mg/dL, 3.9 +/- 3.4 mg/dL and 28.8 +/- 28.3 mL/min/1.73 m(2) respectively. Majority (66.7%) had advanced CKD and 44.4 % were undergoing dialysis. Etiologies of CKD were renal hypoplasia-dysplasia (36.6%), stone-disease (18.9%), posterior-urethral valves (16.7%) and juvenile-nephronophthisis (12. 2%). Mean +/- standard deviation of serum Ca was 8.3 +/- 1.6 mg/dL, P 5.2 +/- 1.7 mg/dL, ALP 418.3 +/- 298 U/L and PTH 370.6 +/- 320.7 pg/ml. Mean 25OHD level was 18.9 +/- 16.8 ng/ml and its levels in males (17.73 +/- 10.63) and females (16.91 +/- 9.74) were similar (p=0.79). Mean 25OHD level was suboptimal in 79 patients (87.8%); 37 (41.1%) had insufficiency, 33 (36.7%) had mild to moderate deficiency whereas 9 (10%) had severe 25OHD deficiency. CONCLUSION: Vitamin D status was suboptimal in 87.8% of cases and 25OHD deficiency was severe in advanced CKD.