Blood levels of 25-hydroxyvitamin D in nephrotic syndrome. Studies in 26 patients.

The blood levels of 25-hydroxyvitamin D (25-HCC) in 26 patients with nephrotic syndrome (proteinuria of 6.5 g/24 h +/- 0.8 SEM) ranged between 1 and 18.6 ng/ml (8.6 +/- 1.0 SEM). This value was significantly lower (P less than 0.01) than that in normal subjects (21.8 +/- 2.3 ng/ml) and patients with chronic renal failure (24.8 +/- 2.3 ng/ml). There was inverse correlation (P less than 0.01) between levels of 25-HCC and magnitude of proteinuria and a direct relation (P less than 0.01) with serum albumin. Reduction in proteinuria was rapidly followed by a rise in blood 25-HCC toward normal. Ionized calcium levels were low in 16 of 26 nephrotic patients irrespective of degree of renal failure. In four of seven nephrotic patients with normal renal function, ionized calcium levels were low and showed an inverse relation with levels of parathyroid hormone. These data show that patients with nephrotic syndrome have low blood levels of 25-HCC probably due to its loss in urine. This derangement is probably responsible for the disorders of calcium metabolism in nephrosis.