Erythropoietin resistance in patients on continuous ambulatory peritoneal dialysis.

Anemia is one of the most serious complications in patients on dialysis. Erythropoietin improves the anemia. However, erythropoietin resistance is sometimes encountered from causes such as functional iron deficiency, secondary hyperparathyroidism, blood loss, or interaction with other drugs. To clarify the interaction between erythropoietin and the renin-angiotensin system, we studied the maintenance dose of recombinant human erythropoietin (rHuEPO) in patients on continuous ambulatory peritoneal dialysis (CAPD) with and without angiotensin converting enzyme inhibitor (ACEIs), angiotensin II type I receptor blockers (ARBs), and calcium channel blockers. We divided 36 hypertensive patients on CAPD into three groups--an ACEI group (n = 12), an ARB group (n = 12), and a Ca channel blocker group (n = 12)--and then we compared the doses of rHuEPO required to maintain the patients' hematocrit (Hct) above 30%. In the Ca channel blocker group, the weekly dose of erythropoietin had not changed significantly at the end of the study (74 +/- 7 U/kg at the end vs. 76 +/- 8 U/kg at the start). The (oral) ACEI group needed a significantly higher weekly dose of erythropoietin at the end of the study (89 -/+ 9 U/kg at the end vs. 74 -/+ 8 U/kg at the start, p < 0.01). The (oral) ARB group also needed a significantly higher weekly dose of erythropoietin at the end of the study (82 -/+ 10 U/kg at the end vs. 76 +/- 8 U/kg at the start, p < 0.05). Furthermore, the weekly dose of erythropoietin required in the ACEI group was significantly larger than that required in the ARB group. We conclude that treatment with ACEIs and ARBs induces erythropoietin resistance in patients on CAPD. The inhibitory effect of ARBs on erythropoiesis is less than that of ACEIs.