Vitamin D deficiency in children with renal disease

Aims: The purpose of this study was to assess the vitamin D status of children with renal disease attending the outpatient clinics of our tertiary nephrology centre, allowing us to determine the prevalence of vitamin D deficiency and study its relationship with glomerular filtration rate (GFR) and serum parathyroid hormone (PTH) concentration. Methods: 90 boys and 53 girls (99 white Caucasians, 38 of South Asian origin and six from other ethnic groups) were enrolled into the study. 18 were on dialysis (15 peritoneal dialysis and three haemodialysis), 61 had a functioning renal transplant (19 with reduced GFR), 18 had chronic renal failure and 46 had a variety of renal disorders with normal renal function. Serum/plasma concentrations of 25(OH) D, 1,25(OH) 2D, PTH, creatinine, calcium, phosphate and alkaline phosphatase were measured. Patients with serum 25(OH) D concentrations of less than 25 nmol/l were considered to be deficient and those with levels of 25 -50 nmol/l considered insufficient. Results: 26% of all patients were 25(OH) D deficient and a further 32% were insufficient. The prevalence in South Asians was higher (87% deficient/insufficient) than in white Caucasians (46% deficient/insufficient, p < 0.001). In children with reduced GFR who were not on dialysis, 25(OH) D levels of less than 50 nmol/l were associated with a high PTH in 90% of cases compared to only 50% of those with normal vitamin D concentrations (p= 0.013). Conclusion: A high proportion of renal patients were vitamin D deficient/insufficient, particularly children of South Asian origin. High PTH values in the setting of reduced GFR might be due to vitamin D deficiency and should lead to estimation of serum 25(OH) D concentration.