Candidate biomarkers for erythropoietin response in end-stage renal disease.

Hyporesponsiveness to erythropoiesis-stimulating agents (ESAs) is important clinically and economically. Escalation of dose may produce harm. Post hoc analyses of clinical trials showed that responsiveness could be predicted by hemoglobin response to a fixed dose escalation. This maneuver requires weeks to months. The study by Merchant et al. offers promise that peptidomic analyses of patient sera and mass spectrometry can identify biomarkers of both responsiveness and resistance to ESAs.