VITAMIN-D METABOLITES IN CHILDHOOD NEPHROTIC SYNDROME

We measured serum levels of total and ionised calcium, phosphate, inta ct parathyroid hormone, 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyv itamin D [1,25(OH)(2)D] and the vitamin D binding protein (DBP) in 14 children with idiopathic nephrotic syndrome and 10 healthy, age-matche d controls. In all nephrotics serum DBP levels were below the normal r ange. Serum 25(OH)D was below 7 ng/ml in 10 of 14 nephrotic children a nd in the low normal range in the remaining 4 patients. The average se rum 1,25(OH)(2)D levels were lower in the nephrotic patients than in t he controls. However, free 1,25(OH)(2)D levels were normal in the neph rotic patients. Both serum 25(OH)D and 1,25(OH)(2)D correlated positiv ely with the concentration of DBP. There was a significant negative co rrelation between serum DBP levels and the urinary protein excretion a nd a significant positive correlation between the urinary excretions o f DBP and albumin. From this study it can be concluded that the nephro tic child is capable of maintaining appropriate serum concentrations o f free calcitriol despite important urinary losses of both substrate a nd bound calcitriol.