Negative effect of angiotensin-converting enzyme inhibitors on erythropoietin response in CAPD 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.

Effect of angiotensin-converting enzyme gene insertion/deletion polymorphism and angiotensin-converting enzyme inhibition on erythropoiesis in patients on haemodialysis

BACKGROUND

Angiotensin-converting enzyme inhibitors (ACEis) improve survival; however, their effect on erythropoiesis remains a matter of debate in this population. Since insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene largely influences serum ACE activity, its effect on erythropoiesis is also anticipated.

METHOD

In this multicentre, cross-sectional study of 660 patients on maintenance haemodialysis, we analysed the effect of ACEi use and ACE gene I/D polymorphism on haemoglobin levels and erythropoietin resistance. Patients were allocated in groups based on genotype and ACEi therapy. We identified 128 matched pairs with I/I and D/D genotypes.

RESULT

There was no difference in haemoglobin levels between genotype groups. Haemoglobin levels were lower in patients on ACEi therapy in the entire cohort (95.5±12.1 g/l vs 97.4±13.4 g/l, p=0.02) and patients with I/D (95.2±11 g/l vs 98.2±11.9 g/l, p=0.04) and D/D (93.3±13.2 g/l vs 97.4±14.2 g/l, p=0.02) genotypes. In patient pairs treated with ACEi therapy, subjects with D/D genotype had lower Haemoglobin level (93.0±12.8 g/l vs 98.2±11.9 g/l, p=0.006) and higher erythropoietin resistance index (ERI) (199.1 vs 175.0, p=0.046) than individuals with I/I genotype.

CONCLUSION

These results indicate that ACEi therapy may increase erythropoietin resistance and worsen erythropoiesis in haemodialysis patients with the D allele.

Antihypertensive Medications and Anemia

Antihypertensive medication use can be associated with a reduction in hemoglobin concentration. The magnitude of such a change is generally small, but in certain instances it can be extreme enough to produce a clinically significant degree of anemia. The mechanistic basis for antihypertensive medication-related changes in hemoglobin concentration include hemodilution, hemolytic anemia, and suppression of red blood cell production, as this occurs most commonly with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. A reduction in hemoglobin concentration in a patient who is receiving treatment for hypertension and does not have an obvious source of blood loss should account for potential antihypertensive therapy involvement.

Pharmacotherapy in congestive heart failure: ACE inhibitors and anemia in congestive heart failure

The use of angiotensin-converting enzyme inhibitors can be accompanied by a number of adverse events, including cough, angioedema, and hyperkalemia, as well as a peculiar form of functional renal insufficiency. Other, less obvious side effects accompany ACE inhibitor use, such as a reduction in red blood cell production. This feature of ACE inhibitor use may be employed to good effect, as in the management of post-transplant erythrocytosis. Alternatively, the suppressive effect of ACE inhibitors on red blood cell production may intensify the anemia of chronic renal failure and/or congestive heart failure. The untreated congestive heart failure patient typically has an increased red blood cell mass as a consequence of increased erythropoietin levels, with the latter governed by congestive heart failure-related renal hypoxia. This is not expressed as an increase in hemoglobin concentration because of the increase in plasma volume that marks advanced congestive heart failure. ACE inhibitor therapy can be expected to both reduce plasma volume and decrease red blood cell production. As a result, the hemoglobin concentration changes very little in the ACE inhibitor-treated congestive heart failure patient and usually falls in the low normal range. Recently, erythropoietin has been employed to good effect in congestive heart failure patients with borderline anemia. (c)2000 by CHF, Inc.