Evidence and implications of haemoglobin cycling in anaemia management

Treatment with erythropoietic-stimulating agents (ESA) has been a major advance for improving the lives of patients with chronic kidney disease (CKD). Treatment, however, differs greatly from normal erythropoietic biology. The ESA drugs are administered episodically, resulting in great fluxes in serum erythropoietin levels. While the erythropoietic efficacy of treatment is clear, there are aspects of pharmacological response that are important to consider if we are to optimize treatment. One such phenomenon recently described, haemoglobin (Hb) cycling, is the repeated, cyclical, up and down movement of Hb levels during ESA treatment. This review will describe the phenomenon of Hb cycling, highlighting potential contributing factors and discussing the possible clinical implications.