Anaemia in dialysis patients requires treatment with frequent dose adjustments. There are two current possible treatments for anaemia which are iron and erythropoietin stimulating agents (ESA). Dosages of these medications are currently guided by a patient's ferritin levels and haemoglobin, but these markers are known to be inaccurate. The current clinical protocol therefore tends towards overuse of both agents which can be associated with toxicity, and the reliance on these markers prevents retrospective assessment of treatment responsiveness. This study is designed to investigate the factors which predict which agent would produce a better response. Patients with a fall in haemoglobin will be given treatment with either iron or an increased dose of ESA as they are currently, but allocated at random rather than by poorly performing biochemical markers. The iron treated and ESA treated groups can then be analysed for factors which predict response in o