[COPD and erythropoiesis: interactions and consequences]

Erythropoiesis is modified in chronic obstructive pulmonary disease (COPD). Tobacco smoke, hypoxaemia, systemic inflammation, and infectious exacerbations are the main factors involved. Polymorphisms in genes involved in the regulation of erythropoiesis probably explain the individual susceptibility and variability in the response. The roles of comorbidities related to COPD and the impact of treatment on erythropoiesis are important confounding factors. While polycythaemia is often related to tobacco smoke and hypoxaemia, it has become less common due to the improvement of COPD follow-up and especially the initiation of long-term oxygen therapy. The control of the main causes is often sufficient, but in cases of severe polycythaemia an erythrapheresis is indicated. Anaemia has recently been reported as a more common and serious complication. It increases dyspnoea and reduces physical activity and quality of life. Its impact on survival and the requirements for healthcare has recently been confirmed. The main approach to the management of anaemia remains exclusion of any curable causes, reducing exacerbations and systemic inflammation, and controlling the comorbidities. Though erythropoietin has some benefits in the so-called "anaemia of chronic disease", this still remains to be confirmed in patients with COPD.