Correlation between Fractional Reabsorption of Sodium and Erythropoietin dose in Peritoneal Dialysis Patients

Background Erythropoietin (EPO) deficiency of chronic renal failure (CRF) may be a functional consequence of decreased glomerular filtration rate and fractional reabsorption of sodium (FR Na ). Decreased FR Na reduces renal oxygen consumption and increases tissue oxygen pressure, resulting in less EPO production. We hypothesized that, in CRF patients, there is a positive relationship between EPO production and FR Na and that, in such patients receiving EPO, a negative correlation is expected between FR Na and EPO dose.Methods Creatinine clearance, FR Na , serum iron, transferrin, transferrin saturation, ferritin, and intact parathyroid hormone (iPTH) levels were measured in 91 peritoneal dialysis patients. The correlation between EPO dose and FR Na was studied.Results Mean EPO dose was 7076 ± 4821 units/week and mean FR Na was 93.40% ± 6.14%. A negative correlation was found between EPO dose and FR Na ( r = -0.28, p < 0.01), and a positive correlation was found between both ferritin and iPTH and EPO dose ( r = 0.39, p < 0.001 and r = 0.35, p < 0.002 respectively). After adjusting for the effect of creatinine clearance, ferritin, and iPTH, there was still a significant correlation between EPO dose and FR Na ( p < 0.05).Conclusion In CRF patients there is a negative correlation between FR Na and EPO dose, which supports the hypothesis that EPO deficiency may be related to the decreased renal oxygen-consuming work of sodium reabsorption.