Serum erythropoietin levels in children with chronic renal failure.

Serum erythropoietin (EPO) was measured in 64 children with chronic renal failure (CRF) by means of the fetal mouse liver cell assay. The results were compared with two control groups consisting of 20 healthy children and 10 with nonrenal anemia. EPO was analyzed according to the mode of treatment and the degree of uremia, anemia, hypoxemia, hyperparathyroidism, and body iron load. Mean EPO was 36 U/liter on conservative treatment (CT) (N = 30), similar to that in healthy children (35 U/liter) and in 15 children with renal transplants (TP, 39 U/liter), but significantly higher than that in 19 patients on regular dialysis (RDT; 16 U/liter) and lower than that in children with nonrenal anemia but with similar hemoglobin (230 U/liter). On CT, EPO was higher with severe uremia (SCr greater than 4 mg/dl) compared with moderate CRF and was inversely correlated with hemoglobin, but on a lower level compared with control, whereas on RDT the correlation became positive. By serial measurements, the decrease of EPO from CT to RDT was confirmed. An inverse relationship between EPO and p50 or the oxygen transport index was detected only on CT and after TP. EPO was inversely correlated with serum ferritin levels on HD. Between EPO and PTH, no correlation was found. Data demonstrate a negative feedback between EPO and the degree of hypoxia in children with CRF. On CT, this regulatory mechanism of erythropoiesis is acting on a lower level than it does in control subjects and is lost on RDT.