Reduced plasma concentration of 1,25-dihydroxyvitamin D in children with moderate renal insufficiency

Reduced plasma concentration of 1,25-dihydroxyvitamin D in children with moderate renal insufficiency. We measured the plasma concentration of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in 39 children comprising three groups: eight with moderate renal insufficiency (GFR of 25 to 50 ml/min/1.73M2, seven of whom had tubulointerstitial disease), eight with severe renal insufficiency (on chronic hemodialysis), and 23 healthy control subjects. The mean plasma concentration of 1,25-(OH)2D was reduced by some 40% (P < 0.002) in the children with moderate renal insufficiency, and by some 80% (P < 0.001) in the children with severe renal insufficiency. In the children with moderate renal insufficiency, the reduced concentration of 1,25-(OH)2D was associated with increased serum concentrations of immunoreactive parathyroid hormone (iPTH) and reduced serum concentrations of calcium and phosphorus. When analyzed over the range of renal function from normal through severely impaired, values of iPTH correlate inversely and significantly with those of 1,25-(OH)2D. Growth was impaired in four of the eight children with moderate renal insufficiency. The results of the current study suggest that in children with moderate renal insufficiency, a reduction in the renal synthesis and in the plasma concentration of 1,25-(OH)2D may be important pathogenetic events in disordered metabolism of calcium and phosphorus, including secondary hyperparathyroidism. Diminution de la concentration plasmatique de 1,25-dihydroxyvitamine D chez des enfants ayant une insuffisance renale moderee. Nous avons mesuré la concentration plasmatique de 1,25-dihydroxyvitamine D (1,25-(OH)2D) chez 39 enfants répartis en trois groupes: 8 avaient une insuffisance rénale modérée (GFR de 25 à 50 ml/mn/1.73m2 sept d'entre eux ayant une néphropathie tubulo-interstitielle), huit ayant une insuffisance rénale sévère (en hémodialyse chronique), et 23 sujets contrôles sains. La concentration plasmatique moyenne de 1,25-(OH)2D était diminuée de 40% (P < 0.002) chez les enfants ayant une insuffisance rénale modérée, et de 80% (P < 0.001) chez les enfants ayant une insuffisance rénale sévère. Chez les enfants ayant une insuffisance rénale modérée, la diminution de la concentration de 1,25-(OH)2D était associée avec une augmentation des concentrations sériques d'hormone parathyroïdienne immunoréactive (iPTH), et avec des concentrations diminuées de calcium et de phosphore. Lorsque les résultats étaient étudiés selon la fonc