End-stage kidneys are capable of increased erythropoietin production.

A relative deficiency of erythropoietin (EPO) is the most important factor responsible for the anaemia of end-stage renal failure. Patients on continuous ambulatory peritoneal dialysis usually maintain a higher haemoglobin concentration than patients on other forms of dialysis. The precise mechanism is uncertain, and there is disagreement over the role of increased EPO production. An 11-year-old boy with end-stage renal failure maintained on overnight cycling peritoneal dialysis developed a reticulocytosis, followed by a marked increase in haemoglobin concentration, shortly after his dialysis schedule was altered to include a full peritoneal cavity during the daytime. This improvement in erythropoiesis was closely associated with an increase in serum EPO concentration. We suggest that the alteration in dialysis may have resulted in enhanced clearance of an inhibitor of EPO production and discuss the possible mechanisms involved.