Biomarker-Defined Iron Deficiency in Heavy Smokers with and without COPD and/or Emphysema

Assess whether iron deficiency prevalence in heavy smokers is higher in presence of COPD and/or emphysema, how the prevalence of iron deficiency is impacted by the biomarker used to define it, and examine the prevalence of anemia and polycythemia in heavy smokers with or without COPD.

A cross-sectional analysis was conducted on 1002 participants from the Norwegian Early Lung Cancer Screening study. All participants underwent chest CT scans, spirometry, and venous blood sampling to analyze iron-related parameters, C-reactive protein (CRP), and hemoglobin. Iron deficiency was defined using transferrin saturation (TSat) <20%, ferritin < cutoff (CRP-dependent), or a combination of both.

The prevalence of iron deficiency varied from 3% to 30%, being highest when defined by TSat <20%, and was more prevalent in participants with COPD. Emphysema was not associated with iron deficiency. Decreasing hemoglobin, increasing soluble transferrin receptor (sTfR) and CRP were associated with TSat <20%. COPD was not independently associated with iron deficiency. Increasing age and sTfR, along with female sex, were associated with ferritin < cutoff. Anemia was more common than polycythemia, with approximately one-third of anemia cases attributable to iron deficiency.

Iron deficiency was more prevalent in heavy smokers with COPD than in those without, but not in individuals with emphysema. TSat <20% identified significantly more cases of iron deficiency than ferritin < cutoff. Eight percent of participants had anemia, while four percent had polycythemia, with neither condition related to COPD or emphysema.