OBSERVATIONS ON SODIUM CHLORIDE RESTRICTION AND UREA CLEARANCE IN RENAL INSUFFICIENCY 1

Abstract

In 2 normal subjects urea clearances, detd. over 24-hr. periods, varied less widely than did the conventional urea clearances detd. over 1-hr. periods. Av. urea clearances over 12-and 24-hr. periods were therefore used to study possible effects of NaCl restriction and administration on renal function in 3 patients with different grades of renal insufficiency. With diet and fluid intake constant, a restricted intake of NaCl was accompanied by a slight elevation of plasma urea N concn. and a slightly diminished av. 24-hr. urea clearance. Administration of NaCl was accompanied by a lowering of plasma urea N concn. and a higher av. 24-hr. urea clearance. In 1 patient with advanced renal insufficiency the plasma urea N decreased from 154 to 26 mgm. per 100 cc. during NaCl administration. Acute restriction of NaCl intake produced hypochloremia with characteristic symptoms, and temporary retention of urea, creatinine and phosphates. Renewed NaCl administration relieved the symptoms and diminished the concns. of urea, creatinine and phosphate in the plasma. In the same patient, both the urea and the creatinine clearances over 24-hr. periods were slightly lower during and shortly after NaCl restriction, becoming somewhat higher during NaCl administration. This method of study in suitable cases may aid in determining the factors responsible for the association, in certain patients, of hypochloremia and azotemia.