Effect of angiotensin-converting enzyme inhibitors on anemia in hemodialyzed patients

Angiotensin-Converting Enzyme Gene Polymorphism and Erythropoietin Requirement

Objectives

To study the effect of angiotensin-converting enzyme (ACE) polymorphisms II, ID, and DD on erythropoietin (EPO) requirement in patients on continuous ambulatory peritoneal dialysis (CAPD) therapy.

Design

Retrospective observational study.

Setting

CAPD Unit, Royal London/St. Bartholomews Hospital, London, UK.

Patients

46 patients on the transplant waiting list (age 20 – 70 years), on CAPD therapy for an average of 28 months, seen consecutively over a period of 3 months in the outpatients department.

Main Outcome Measures

Primary end point: EPO dose requirement in different ACE genotypes. Secondary end points: C-reactive protein, ferritin, parathyroid hormone, Kt/V, duration of dialysis, folate, cause of renal failure, and whether or not patients were on ACE inhibitor therapy.

Results

There was a statistically significant difference ( p < 0.05) in EPO requirement in the II/ID group compared to the DD group. The mean ± standard error of EPO for the II/ID group was 144 ± 15 U/kg/week, and for the DD group, 87 ± 9 U/kg/ week. The difference in EPO requirement could not be explained by age, C-reactive protein, ferritin, parathyroid hormone, Kt/V, duration of dialysis, folate, cause of renal failure, or whether or not patients were on ACE inhibitor therapy.

Conclusion

In CAPD patients, ACE genotype has predictive value when determining the EPO dosage, as the II/ID genotype may be associated with a suboptimal response.

ACE inhibitors do not induce recombinant human erythropoietin resistance in hemodialysis patients

Angiotensin-converting enzyme (ACE) inhibitors may exacerbate anemia in patients with chronic renal failure, as well as in dialysis patients. To better answer this question, a prospective, crossover study was conducted to evaluate the effect of ACE inhibitors on recombinant human erythropoietin (rHuEPO) requirements in hemodialysis patients. Patients administered an ACE inhibitor when entering the study remained on this drug for the initial 4 months and were then switched to another antihypertensive agent for 4 more months. Patients not initially administered an ACE inhibitor were switched to lisinopril at 4 months. rHuEPO doses were adjusted using a sliding scale based on weekly laboratory hematocrit values. The inclusion criteria were met by 51 patients undergoing dialysis. Demographics were as follows: 61% were women, 64% were black, 46% had diabetes, average age was 53.2 +/- 13.3 years, and time on hemodialysis was 38.0 +/- 44.5 months. Thirty-three patients completed the study. Hematocrit averaged 32.7% +/- 1.9% while on ACE inhibitor therapy and 33.1% +/- 2.1% off ACE inhibitor therapy (P = 0.217). There was no difference in rHuEPO dose per treatment during each period (3,500 +/- 1,549 U on ACE inhibitor therapy versus 3,312 +/- 1,492 U off ACE inhibitor therapy; P = 0.300). No significant differences were found in degree of blood pressure control or various clinical and laboratory parameters that might be associated with rHuEPO resistance between the two periods. Similarly, no differences were found in hospitalization days, duration of infections, or transfusion requirements. These findings suggest that ACE inhibitors do not contribute to rHuEPO resistance in hemodialysis patients.