Endogenous Erythropoietin Levels and Anemia in Long-Term Renal Transplant Recipients

Abstract

Background/Aim: Although anemia is a common complication after renal transplantation (RT), data concerning endogenous erythropoietin (EPO) levels in long-term RT recipients are rare. The goal of this study was to evaluate the prevalence of anemia within 6 months to 5 years after RT and to assess the relationship between the serum concentrations of endogenous EPO, graft function and grade of improvement of anemia. Methods: 140 patients who had undergone RT were included in the group: 89 males (63.6%) and 51 females (36.4%), with an average age 46.8 ± 12.8 years. The serum concentrations of EPO and creatinine (Cr) were tested in all the individuals and the values of the red blood component of blood count, serum ferritin (SF), plasma iron concentration, plasma total iron-binding capacity (TIBC), transferrin saturation (TS), folic acid and vitamin B₁₂ levels in the serum were determined. A statistical analysis of the results was performed using the correlation analysis, Mann-Whitney U test and Duncan’s multiple range test. Results: Normal blood count values were found in 91 patients (65%), and a mild grade of anemia with a mean hemoglobin (Hb) 114.4 ± 11.9 g/l was observed in 45 patients (32.1%), and 4 patients (2.9%) fulfilled the diagnostic criteria for post-transplantation erythrocytosis. Individuals with normal Hb values had a mean EPO serum concentration of 39.3 ± 12.3 mU/ml (median 37.2) and the mean Cr was 133.8 ± 36.9 µmol/l (median 122). Patients with anemia (Hb <120 g/l in females, Hb <130 g/l in males) had a mean EPO value of 47.0 ± 26.6 mU/ml (median 36.0) and a mean Cr of 203.8 ± 108.9 µmol/l (median 181). The difference in the Cr values was statistically significant (p < 0.0001), while the difference between the EPO concentrations was not significant. No relation of EPO serum concentration with regard to graft function was found in the analysis. A lack of storage iron (SF <10 µg/l in females, SF <22 µg/l in males) was found in 16 patients (11.4%), and a lack of functional iron (TS <20%) was found in 27 patients (19.3%). Conclusions: Theprevalence of anemia in patients after transplantation was 32.1%. The most common cause of anemia is insufficient graft function development. The achieved values of the red component of blood count have no relation to the endogenous EPO serum concentrations.