Erythropoietin and renin after renal transplantation.

Serum concentration of erythropoietin (EP) was measured with a hemagglutination inhibition technique and plasma renin activity (PRA) with a radioimmunoassay for angiotensin I in 26 renal transplant recipients 2-54 months after renal transplantation. In all patients, the EP values were significantly correlated with the levels of PRA (r = 0.76 p less than 0.001) and hematocrit values (r = 0.72, p less than 0.001). In one patient, erythrocytosis and high blood pressure associated with high EP and PRA levels disappeared after bilateral nephrectomy of his own kidneys. The results indicate an as yet unidentified relationship between the production of EP and renin.