The effect of urea on the postoperative excretion of electrolytes

1. 1. Two randomly selected groups of 15 patients each were studied to determine the effect of the administration of 40 Gm. of urea in a 4 per cent solution upon the urinary volume and electrolyte excretion in the postoperative period. The urea was given in the 24-hour period immediately following operation to one group of patients, while the other group received equal amounts of sodium dextrose and fluids, but no urea. 2. 2. Sodium excretion was markedly and significantly (P = < 0.05) increased in the 24-hour period when urea was given. The total sodium excretion for this period ranged as high as 200 mEq. Maximal losses of sodium did not necessarily occur in the patients with the greatest urinary volume. 3. 3. Urea is finding increasing clinical use in neurosurgery and general surgery. Amounts of urea much greater than those given here are sometimes used. Clinicians should be aware of the magnitude of the sodium losses which may take place, and be prepared to replace them.