Serum erythropoietin levels and their correlation with the erythropoietic system in hemodialysis patients and renal allograft recipients

BACKGROUND: Following renal transplantation, serum erythropoietin (EPO) levels gradually increase during the first 2 to 3 months. However, some transplant recipients continue to remain anemic. The aim of the present study was to correlate serum EPO concentrations with hematocrit (Hct) and hemoglobin (Hb) levels in hemodialysis (HD) patients and renal allograft recipients. METHODS: In a comparative cross-sectional study, serum EPO concentrations and Hb and Hct levels were measured in 35 chronic HD patients and 40 transplant recipients who had stable kidney function for at least 6 months after transplantation (group 1). The HD patients were further divided based on their recombinant human (rHu) EPO supplementation into those who received rHu EPO during dialysis (group 2A, n=15) and those who were not on rHu EPO (group 2B, n=20). Data are presented as mean values +/- SD. The statistical analysis was performed by SPSS version 11.0 using chi-square, ANOVA, and Pearson correlation tests. A general linear model (GLM) was used to compensate for the effects of age. The P value for significance was set at .05. RESULTS: Group 2B patients tended to be older than groups 1 and 2A (P=.014). The sex ratios were comparable among groups. Mean EPO level was 17.09 +/- 10.99 mIU/mL in recipients, which was comparable with that of HD patients (18.54 +/- 26.18 mIU/mL; P>.05). No significant correlation was observed between the serum EPO concentrations and Hb and Hct levels in recipients (P>.05). When comparing the 3 groups, EPO was not correlated with Hct and Hb in any group. Hb and Hct were significantly higher among HD patients not on rHu EPO therapy (P=.02). GLM, with age as a covariate, did not yield a significant difference between EPO levels of the studied groups (P=.36). CONCLUSIONS: This study showed that serum EPO level was in the normal range in recipients and HD patients. We were not able to find any correlation between Hb and Hct levels and EPO concentrations in any group of patients irrespective of rHu EPO supplementation. Hence, impaired EPO stimulatory effects may be considered a potential contributor to anemia in these patients.