Observations on edema formation in the nephrotic syndrome in adults with minimal lesions

Abstract

Ten adult patients with the nephrotic syndrome and minimal lesions on renal biopsy were studied while receiving a salt poor diet before and after 13 prednisone-induced remissions.

They were selected because the finding of a slight to moderate increase in blood volume in all of them and of an elevated blood pressure level in some of them was at variance with the expected hypovolemia.

After remission, blood pressure decreased in 12 and plasma volume in 10 patients, whereas plasma renin activity (PRA) increased in eight and decreased in three patients. Creatinine clearance, which had been severely depressed in four subjects, increased in all, whereas radioactive chromium sulfate (51Cr) EDTA clearance increased in six of seven instances. In contrast, renal plasma flow (125I-hippurate clearance) was normal or increased in the nephrotic phase and decreased in five of seven cases, resulting in an increase towards normal of the very low filtration fraction.

These results lend no support to the conventional concept that hypovolemia is the main factor responsible for the maintenance of edema in this condition and suggest that other factors, such as impaired glomerular permeability, may be important.

Although no combined measurements of these hemodynamic parameters have been reported in a similar group of patients, many data from the literature suggest that some degree of hypervolemia is a common finding in adults with an established nephrotic syndrome.