Hemoglobin can help as a promising biomarker to assess the clinical outcomes of patients with COPD. A US-based study has revealed that unusually high or low levels of hemoglobin were linked to worse clinical outcomes. This finding lays the foundation for research regarding potential therapeutic targeting of haemoglobin in disease management.  COPD, as a disease linked with inflammation, typically disturbs the process by which the body makes blood cells by favoring the production of certain immune cells at the expense of red blood cells, among others. While several studies in the past have linked anemia to poorer clinical outcomes, not many have looked at polycythemia. Hence this study is trying to bridge this gap in knowledge and thus the relationship between hemoglobin levels through its whole range and the clinical outcomes of COPD patients.