Measurement of erythropoietin in anephric children. A report of the Southwest Pediatric Nephrology Study Group.

Serum erythropoietin (Ep) levels were measured using a highly sensitive radioimmunoassay in 69 children undergoing chronic dialysis; 31 were anephric, whereas 38 were non-nephrectomized (nephric). Twenty-nine normal children were studied as controls. Serum Ep levels in the anephric group were much higher than anticipated (mean 19.7 +/- 1.8 mU/ml), albeit significantly lower than those measured in normal children (mean 26.2 +/- 2.4 mU/ml, P less than 0.05), or in nephric children on dialysis (33.0 +/- 2.9 mU/ml, P less than 0.001). Anephric children on peritoneal dialysis (PD) had significantly (P less than 0.05) higher serum levels of Ep (22.7 +/- 2.4 mU/ml, n = 19) than anephric children on hemodialysis (HD) (15.1 +/- 2.3 mU/ml, n = 12). There was no significant difference between Ep levels in anephric patients dialyzed for less than or equal to 1 year (19.6 +/- 2.0 mU/ml, n = 20) compared with anephric patients dialyzed for more than 1 year (20.0 +/- 3.9 mU/ml, n = 11). Although serum Ep levels showed a tendency to increase with time after nephrectomy, the mean values for less than 3 months (14.7 +/- 1.9), 3 months-12 months (21.0 +/- 2.7), and greater than 12 months (21.6 +/- 6.0) were not significantly different from each other. This demonstration of relatively normal levels of serum Ep in anephric children suggests that extrarenal sites of Ep production are able to exert a significant response to severe anemia in patients who are devoid of renal parenchyma.