Postrenal transplant erythrocytosis and insertion/deletion polymorphism of the angiotensin converting enzyme gene

Renin-angiotensin system polymorphisms and hemoglobin level in renal allografts: a comparative study between losartan and enalapril

INTRODUCTION

In this study, hemoglobin (Hb) concentrations secondary to enalapril (E) or losartan (L) therapy were evaluated with respect to renin-angiotensin system (RAS) polymorphisms in renal transplant recipients.

MATERIALS AND METHODS

After determination of RAS polymorphisms [angiotensin-converting enzyme (DD, non-DD), angiotensinogen (TT, non-TT), and angiotensin receptor type 1 (CC, non-CC)] by polymerase chain reaction, 70 renal transplant recipients were recruited to four groups randomly: first and second groups were treated with E (10 mg/d, 15 patients) and L (50 mg/d, 20 patients) alone, respectively. The third group received E+L (10 mg/d + 50 mg/d, 13 patients) and the fourth group (22 patients) received no medication. The treatment protocol was followed for 16 weeks. Complete blood counts were checked before treatment and every 2 months. P<.05 was considered to indicate statistical significance.

RESULTS

Treatment for 4 months decreased the Hb level in the E+L (14.15 +/- 0.94 to 12.06 +/- 0.66 g/dL, P=.000), E (14.00 +/- 0.86 to 13.11 +/- 0.82 g/dL, P=.02), and L (14.12 +/- 0.90 to 12.10 +/- 2.35 g/dL, P=.01) groups, but not in the control group (13.55 +/- 0.70 to 13.36 +/- 0.69 g/dL, P>.05). None of these regimens showed greater Hb reduction than the others (P>.05). None of the RAS polymorphisms predicted the intensity of the reduced Hb according to the type of treatment (P>.05). Any other sets of RAS polymorphisms (alone or together) did not impact on Hb levels pre- or post-intervention (P>.05).

CONCLUSION

Our findings suggest that low dosages of E and/or L decrease Hb levels regardless of the RAS polymorphisms.

Influence of Angiotensin-Converting Enzyme Polymorphism Gene, IGF-1, and Other Factors in the Response Rate of Hematocrit to Enalapril Treatment in Patients With Posttransplant Erythrocytosis

A significant relationship between hematocrit values and serum parameters such as the insulin like growth factor (IGF-1) and calcium was observed in patients with posttransplant erythrocytosis (PTE). Since angiotensin-converting enzyme inhibitors (ACEI) decrease hematocrit (Ht) levels in these patients, ACE genotype should play an important role. We designed this study to investigate whether ACE genotype or baseline concentrations of IGF-1, IGF-blood binding protein 3 (BP3), growth hormone (GH), or Ca influenced the response of Ht to ACEI treatment. Twenty-one kidney graft recipients with PTE were treated with enalapril (2.5 to 5 mg/d) for 1 year. IGF-1, BP3, GH, Ca, and Ht were determined before as well as 15, 30, 90, 180, and 365 days after enalapril treatment. ACE polymorphism was also determined. Enalapril treatment significantly decreased Ht levels. Only IGF-1 baseline levels showed a positive correlation to the decreased Ht (P < .025). ACE genotype as determined in 18 patients, showed no correlation with the response to enalapril. Patients with ACE genotype II showed a tendency to an earlier display of PTE. We conclude that low doses of enalapril decrease Ht levels in PTE patients; that PTE begins earlier in patients with II ACE genotype; and that only IGF-1 baseline levels influence the Ht decrease after treatment. These observations suggest that ACEI decrease the Ht via an inhibitory effect on IGF-1, which has a stimulary effect on erythropoiesis.

Comparison of the effects of enalapril and losartan on posttransplantation erythrocytosis in renal transplant recipients: prospective randomized study

BACKGROUND

The aim of this prospective randomized study was to compare the safety and efficacy of enalapril (E) and losartan (L) in the treatment of posttransplantation erythrocytosis and the effect of the ACE genotype on response to therapy.

METHODS

Twenty-seven (24 male and 3 female, mean age 34+/-8 years) renal transplant recipients with erythrocytosis were treated either with E (15 patients) (10 mg/day) or L (12 patients) (50 mg/day) for 8 weeks.

RESULTS

The hemoglobin levels were significantly decreased in the L (17.1+/-0.7 to 15.9+/-1.3 g/dl, P=0.01) and E groups (17.4+/-1.1 to 14.9+/-2.2 g/dl, P=0.001). Among the responders who discontinued treatment, there was a trend for longer time to relapse in the L group (7.38+/-3.75 months; 95% confidence interval: 0.03-14.7) compared with the E group (2.75+/-0.70 (95% confidence interval: 1.37-4.13) (P=0.11). Decrease in hemoglobin was more prominent with E compared with L (-3.26+/-0.65 vs. -1.70+/-0.39 g/dl, P=0.05). Decrease in hemoglobin levels between DD and non-DD genotype groups was similar (-2.0+/-1.5 vs. -1.7+/-2.3 g/dl, P=0.69).

CONCLUSIONS

Enalapril caused a greater decrease but faster relapse in hemoglobin levels compared with losartan in patients with posttransplantation erythrocytosis. The DD type polymorphism had no effect on response.