EFFECT OF ERYTHROPOIETIN ON RENAL EXCRETION OF A SODIUM LOAD

To determine whether erythropoietin alters the renal excretion of a so dium load in humans, we administered either erythropoietin (150 units/ kg) or vehicle intravenously in a randomized crossover design to six n ormal white men on day 4 of a controlled sodium diet. After erythropoi etin administration, the subjects were given 2 L normal saline solutio n intravenously over 4 hours. All urine was collected for 4 days after drug administration. Serum sodium and creatinine levels and blood pre ssure were determined 0, 4, 8, and 24 hours after drug administration. Peripheral renin activity and aldosterone levels were determined 0, 4 , and 8 hours after drug administration. Erythropoietin significantly decreased total sodium excretion during the 4 days after drug administ ration (erythropoietin = 784 +/- 46 mEq/4 days versus control = 840 +/ - 41 mEq/4 days; p < 0.001). Erythropoietin did not alter creatinine c learance, blood pressure, or the changes in plasma renin activity and aldosterone caused by the saline load. We conclude that erythropoietin decreases urine sodium excretion after a sodium load in normal human subjects without altering glomerular filtration rate, blood pressure, or plasma renin activity.