Serum concentrations of 25-hydroxyvitamin D and 24,25-dihydroxyvitamin D in patients with various types of renal disease.

Serum concentrations of 25-hydroxyvitamin D (25OHD) and 24,25-dihydroxyvitamin D (24,25(OH)2D) in patients with various types of renal disease were measured by a competitive protein binding assay. There was a significant (P less than 0.001) inverse correlation between serum levels of either 25OHD or 24,25(OH)2D and the degree of proteinuria in patients with chronic glomerulonephritis or idiopathic nephrotic syndrome. The ratio of 24,25(OH)2D to 25OHD was relatively low in patients with creatinine clearances (CCr) less than 30 ml/min/1.48 m2, while the ratio was higher in those with clearances greater than 85 ml/min/1.48 m2. There was a linear correlation (r = 0.783, P less than 0.001) between the ratio and the CCr in patients whose CCR ranged from 30 to 85 ml/min/1.48 m2. The 24,25(OH)2D/25OHD ratio also appeared to be correlated significantly (P less than 0.001) with the PSP-test. The serum levels of 25OHD and 24,25(OH)2D were lowered in nephrotic patients during treatment with prednisolone. The serum levels of 24,25(OH)2D were increased by 1 alpha-hydroxyvitamin D3 treatment in patients with chronic renal failure.