Vitamin D deficiency is associated with short stature and may influence blood pressure control in paediatric renal transplant recipients

Vitamin D deficiency is common in adult renal transplant recipients, but data in children are scarce. Vitamin D is shown to have multiple effects on the cardiovascular system, renal function, and maintenance of bone health. We hypothesized that 25(OH)D deficiency is common in pediatric renal transplant recipients, and may be associated with hyperparathyroidism, short stature, renal function, and blood pressure control. We recruited 106 children during the winter/spring season who had a functioning renal transplant for at least 3 months. Twenty-five hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] were measured and correlated with clinical and biochemical parameters. Of the renal transplant patients, 38% were 25(OH)D deficient, 54% had insufficient levels, and only 8% had adequate 25(OH)D levels. Despite alfacalcidol supplementation in 59 (56%) patients, parathyroid hormone was increased in 58 (55%) and showed an inverse correlation with 25(OH)D (p = 0.0003, r = 0.61) but not with 1,25(OH)(2)D levels. Height standard deviation score (SDS) correlated with 25(OH)D (p = 0.007, r = 0.42) and time post transplantation (p = 0.02, r = 0.23); both were significant and independent predictors of height SDS. 25(OH)D inversely correlated with systolic BP SDS (p = 0.02, r =-0.26); this association was lost on multiple regression analysis, but 25(OH)D was the only modifiable risk factor for hypertension. There was no correlation with estimated GFR or proteinuria. In conclusion, 25(OH)D deficiency is common in pediatric renal transplant recipients and correlates with hyperparathyroidism and short stature. 25(OH)D deficiency may be a modifiable risk factor for hypertension in transplant recipients. Further studies are required to test if routine supplementation with ergo or cholecalciferol is safe and effective in children after renal transplantation.