DIAGNOSTIC USE OF RENAL-VEIN ERYTHROPOIETIN MEASUREMENTS IN PATIENTS WITH RENAL-ARTERY STENOSIS

The relationship between the renin-angiotensin system and erythropoietin was studied in twenty patients with renal artery stenosis and hypertension. Ten of the patients had a unilaterally activated renin-angiotensin system (group 1), while ten patients had not (group 2). Plasma erythropoietin was simultaneously measured in a brachial artery and both renal veins before and 5 and 30 min after an intravenous injection of 1.25 mg enalaprilat. The mean (+/- SD) arterial erythropoietin concentration was 27.3 +/- 16.8 mU/ml in group 1 and 14.1 +/- 11.3 mU/ml in group 2 patients (P < 0.05). There was no significant change after enalaprilat i.v. in either group. The venous erythropoietin concentration in plasma from the stenotic kidney did not differ from that of the contralateral kidney. The higher erythropoietin concentration in group 1 patients may be explained by a systemic stimulatory effect of the renin-angiotensin system on erythropoietin production. As no side-differences were found, renal vein as well as peripheral erythropoietin measurements cannot be used as a tool in the diagnosis of the functional significance of a renal artery stenosis.