RESUMO
The two most common causes of death in patients with chronic kidney disease (CKD) are cardiovascular diseases and infections, and both have been linked to impaired vitamin D levels and dysregulated immune response. The aim of this work is to study the relation between vitamin D levels in children with end-stage renal disease (ESRD) on regular hemodialysis (HD) and their immune status. This case-control study was conducted at the Nephrology Unit, Department of Pediatrics, the Zagazig University Hospital, from April 2010 to August 2010. We studied 27 children with ESRD on regular HD (group-A) whose mean age was 8 ± 1.3 years; there were 15 males and 12 females. The study patients were divided into two groups depending on the degree of vitamin D deficiency; group-A1 had 12 patients, all of whom had vitamin D deficiency defined as serum concentration of 25-hydroxy vitamin D3 [25(OH) D3] of 15-30 ng/mL. Group-A2 had 15 patients with more severe vitamin D deficiency (<15 ng/mL). Twenty healthy age- and sex-matched children served as the control group (group-B); their mean age was 7.8 ± 1.6 years and they included 12 males and eight females. All subjects underwent thorough history taking, clinical examination and the following investigations: complete blood count, lymphocyte count, blood urea, serum creatinine, total serum calcium, ionized calcium, serum phosphorus, plasma 25(OH)D3, intact para-thormone (iPTH), serum interleukin-10 (IL-10) and soluble IL-2 receptor (SIL-2R). We found that the vitamin D level was significantly lower in the patient group (group-A) than in the control-group (group-B). The IL-10 level was significantly lower in group-A than in group-B, and the SIL-2R level was significantly higher in group-A than in group-B. We found a significant positive correlation between serum 25(OH)D3 levels and serum IL-10, while there was a negative correlation between 25(OH)D3 levels and SIL-2R; this correlation was not significant. Our findings suggest that 25(OH)D3 levels affect the immune state in patients through their effect on both limbs of immunity, the anti-inflammatory and the pro-inflammatory, but the effect was higher on the anti-inflammatory IL-10. We conclude that the serum levels of vitamin D are lower in children with ESRD than in age-matched controls, and that it is significantly positively related to the anti-inflammatory IL-10 and negatively related to the pro-inflammatory SIL-2R. Further studies are required to throw more light on the role of vitamin D supplementation in children with ESRD in maintaining immune balance.