[Intrarenal mechanisms of the regulation of homeostasis in children with nephrotic syndrome].
Overall 40 patients with associated glomerulonephritis and the nephrotic syndrome were examined for renal response to the induced shifts in water balance: tests with 18-hour water deprivation characterizing concentration function of the kidneys, followed by water loading (22 ml/kg bw) which allows estimation of water excretion function and osmotic dilution. Osmotic concentration defect was revealed. It manifested in a decrease of osmotic concentration of the urine, a reduction of the concentration index according to creatinine. It should be mentioned that the more preserved was the magnitude of the concentration index the more this was ensured by sodium reabsorption, decrease of its excretion. Meanwhile osmotic concentration of the urine was determined by urea excretion. Study of partial functions in water diuresis discovered a dramatic lowering of sodium-free water clearance characterizing participation of the kidney in the maintenance of effective osmotic pressure of the plasma and reflecting the intensity of distal sodium reabsorption.