Iron deficiency is more common in patients with chronic obstructive pulmonary disease (COPD) than in those without the lung condition, according to the results of a study published in BMJ Open
on 9 July 2015.
The findings are potentially significant for the three million people in the UK who have COPD, say the researchers behind the University of Oxford study, who now plan a two-year follow-up study in which COPD patients will receive intravenous iron to see if it has an impact on their disease and prognosis.
The original observational study involved 113 people with moderately severe COPD who had their iron deficiency measured and compared with a control group of 57 healthy individuals.
The researchers found that 18% of the COPD patients were iron-deficient compared with 5% of the control group.
Levels of C-reactive protein (CRP) were significantly higher in the iron-deficient COPD patients (median 10.5mg/L versus 4.0mg/L; P<0.001), who were also more hypoxaemic than those whose iron levels were replete (median resting peripheral arterial oxygen saturation 92% versus 95%; P<0.001).
Iron-deficient patients were more likely to have reported COPD exacerbations in the year leading up to the study and had worse exercise tolerance levels. There was no difference between the iron-deficient and iron-replete COPD patients in terms of smoking status, average number of cigarette packs smoked or the proportion receiving oxygen therapy. Haemoglobin levels were also not significantly different between the two groups.
“Non-anaemic iron deficiency is common in COPD and appears to be driven by inflammation,” say the researchers. “Given that intravenous iron therapy has been shown to be beneficial in other chronic diseases, it should be explored as a novel therapeutic option in COPD.”
Richard Russell, a consultant respiratory physician and medical adviser for the patient group the British Lung Foundation, says the findings are interesting but hard to interpret. “People with COPD who had iron deficiency had higher levels of CRP, which means inflammation,” he explains. “It’s possible that the inflammation is driving the iron deficiency and the idea that inflammation causes iron deficiency is important.”
Russell questioned whether treating patients with iron would help. “These patients aren’t short of dietary iron; it’s more to do with the way they utilise the iron and hold on to it.”
However, he says taking iron as part of a multivitamin is generally safe. “There is a hint of a story here,” he adds.
 Nickol A, Frise M, Cheng H-Y et al. A cross-sectional study of the prevalence and associations of iron deficiency in a cohort of patients with chronic obstructive pulmonary disease. The B MJ Open 2015;5:e007911. doi:10.1136/bmjopen-2015-007911.