CALCIUM METABOLISM IN NEPHROSIS. I. A DESCRIPTION OF AN ABNORMALITY IN CALCIUM METABOLISM IN CHILDREN WITH NEPHROSIS

Abstract

In 1923, not many years after Epstein's (1) original characterization of lipoid nephrosis, Sal-vesen and Linder (2) first observed a lowering of the serum calcium concentration which paral-leled the decrease in serum protein level in pa-tients with this disease. ' In addition, two other features indicating a disturbance of calcium me-tabolism in nephrosis have been described. Boyd, Courtney, and MacLachan in 1926 (5) and Scriver in 1928 (6) both noted an excessive loss of calcium in the feces and a diminished excretion in the urine. In the course of a systematic study of children with nephrosis in this hospital over the past 5 years, a further indication of abnormal calcium metabolism has come to our attention, namely, a generalized decalcification of the skeleton as ob-served by x-ray. The degree of this decalcifica-tion varies roughly with the severity and dura-tion of the disease; in 2 instances in our experi-ence, fractures have occurred after relatively slight trauma. Some degree of decalcification is often demonstrable within a month after detection of the disease. The studies reported in this and a subsequent paper were designed to correlate the x-ray changes 1These authors, accepting the theory that part of the serum calcium is bound to the proteins and thereby ren-dered non-ionizable and non-diffusable, came to the con-clusion that the deficiency in the serum calcium was entirely in this fraction, and that the ionized or diffusible portion was at a normal concentration. They based their conclusion on the facts that tetany never occurred in these patients, even when the total serum calcium level fell to "tetanic " levels, and that edema fluid contained as high a concentration of calcium in nephrotic patients as in cardiac patients who had a normal serum calcium level. Since then, Liu (3) has shown by ultrafiltration that the diffusible calcium in the serum of these subjects is within normal limits, and McLean and Hastings (4) with the frog-heart technique have demonstrated that the ionized calcium is also normal. in the bones with the alterations metabolism. in calcium