Vitamin D and parathyroid hormone status in children with the nephrotic syndrome and chronic mild glomerulonephritis.

The serum concentrations of 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), calcium, creatinine, albumin and immunoreactive parathyroid hormone (iPTH) were measured in eight children with chronic glomerulonephritis not treated with prednisone (group I), in nine non-edematous children with the nephrotic syndrome treated with prednisone for more than 18 months (group II) and in five children with overt edema also treated with prednisone (group III). Serum creatinine was under 1.2 mg/dl in all 22 patients. Reductions in serum calcium, albumin and 25(OH)D were found in group III patients only, whereas both group II and group III patients showed reduced values of 1,25(OH)2D (p less than 0.001 vs. group I or controls). Chronic glucocorticoid administration in children with glomerulonephritis and minimally impaired renal function (group II) is associated with a reduction in the circulating level of 1,25(OH)2D, since children with comparable type and degree of renal disease but non glucocorticoid treatment (group I) have normal 1,25 (OH)2D values. Children with nephrotic edema (group III) have greater reduction of 1,25(OH)2D values, as well as lower 25(OH)D values and serum calcium values, presumably related to a urinary loss of vitamin D-binding protein. No changes in iPTH were evident in either glucocorticoid-treated or edematous patients, suggesting that the acute elevation in iPTH seen after prednisone treatment is an acute phenomenon. Additional short-term studies are needed to more clearly define the effect of glucocorticoids on vitamin D metabolism.