Vitamin D insufficiency and hyperparathyroidism in children with chronic kidney disease

Chronic kidney disease (CKD) is associated with altered calcium-phosphate homeostasis and hyperparathyroidism due to decreased activity of 1α-hydroxylase and impaired activation of 25-hydroxyvitamin D3 [25(OH)D3]. In some patients these problems start earlier because of vitamin D deficiency. A retrospective review of patients followed in the chronic renal insufficiency clinic at Children’s Hospital of Michigan assessed the prevalence of vitamin D deficiency in CKD stages 2–4 and evaluated the effect of treatment with ergocalciferol on serum parathormone (PTH). Blood levels of 1,25 dihydroxyvitamin D3, 25(OH)D3, and parathormone (PTH) were examined in 57 children (40 boys; mean age 10.6 years). Of 57 subjects, 44 (77.2%) had 25(OH)D3 levels ≤30 ng/ml, with overall mean of 26.4 ± 14.3 ng/ml. PTH for patients with 25(OH)D3 levels >30 ng/ml was 67.84 ± 29.09 ng/ml and in the remaining patients was elevated, at 120.36 ± 86.42 ng/ml (p = 0.05). Following ergocalciferol treatment (22), PTH decreased from 122.13 ± 82.94 ng/ml to 80.14 ± 59.24 ng/ml (p < 0.001) over a period of 3 months. We conclude that vitamin D deficiency is common in children with CKD stages 2–4 and is associated with hyperparathyroidism in the presence of normal 1,25 dihydroxyvitamin D3. Its occurrence before significant renal impairment is noteworthy. Early diagnosis and appropriate treatment is emphasized.