Hemoglobin, erythropoietin and systemic inflammation in exacerbations of chronic obstructive pulmonary disease

BackgroundSystemic inflammation may represent a possible cause of anemia. Previous data support that anemic patients with COPD present high erythropoietin (EPO) levels, suggestive of EPO resistance, possibly mediated through inflammatory mechanisms.ObjectivesWe aimed to determine whether systemic inflammation, which is usually up-regulated during exacerbations of COPD (ECOPD) is associated with low hemoglobin levels expressing erythropoietin resistance.MethodsHemoglobin (Hb), EPO and serum biomarkers of systemic inflammation [CRP, TNF-α, fibrinogen and IL-6] were assessed at three time points (admission, resolution and stable phases) in a selected cohort of 93 COPD patients.ResultsHemoglobin levels were significantly lower on admission compared to resolution and stable phases (median 12.1 g/dl [interquartile ranges 11.2–12.7], vs 13.5 [12.4–14.3] vs 13.4 [12.7–14.08], respectively p = 0.002), whereas EPO was significantly higher on admission compared to resolution and stable phases. A negative association between Hb and IL-6 and a positive association between EPO and IL-6 were observed only during the acute phase of exacerbation. EPO and Hb were negatively associated during the acute phase, whereas they were positively associated during discharge and stable phase.ConclusionsIn this observational study we have shown that during admission for ECOPD Hb levels are decreased and EPO levels are increased. We have also identified a negative association between Hb and EPO. The above association is mainly related to increased IL-6 levels, indicating a possible EPO resistance through the mechanism of increased systemic inflammatory process.