Meeting the challenges of a new millennium: optimizing the use of recombinant human erythropoietin.

Optimizing the use of recombinant human erythropoietin (r-HuEPO) involves choosing an appropriate dose regimen and target haemoglobin level, addressing factors that inhibit response, and considering appropriate adjuvant therapy. Subcutaneous administration of r-HuEPO two or three times weekly is optimal for most patients. Early detection and treatment of iron deficiency is mandatory. Measurement of the percentage of hypochromic red blood cells is a reliable marker of functional iron deficiency, and the treatment of choice is intravenous iron. Other factors that can affect the response to r-HuEPO include blood loss (sometimes occult), infection, inflammation, hyperparathyroidism with marrow fibrosis, aluminium toxicity, vitamin B12/folate deficiency, haemolysis, bone marrow disorders, haemoglobinopathies, under-dialysis and possibly angiotensin-converting enzyme inhibitors. These factors should be identified and corrected where possible. Ascorbic acid, vitamin D, folic acid, carnitine, other cytokines and growth factors have all been shown to augment the response to r-HuEPO in some patients. Further research is required before any of these adjuvant therapies can be incorporated into routine clinical practice. With regard to target haemoglobin value, the current practice is to aim for a level of 10-12 g/dl, but it may be argued that a higher target would achieve greater benefits in terms of physical performance, quality of life, and possibly cardiac morbidity and mortality. International multicentre trials are currently in progress to address this issue, as are studies on other substances that may be able to stimulate erythropoiesis.