Iron Deficiency in Cardiovascular Disease　- Diagnosis, Clinical Implications, and Future Directions.

Iron is an essential requirement for normal cellular function and oxygen transport. Deficiency of iron, due to suboptimal intake, blood loss, malabsorption or maldistribution is the most common nutrient deficiency worldwide. Iron deficiency (ID) has traditionally been ignored until anemia develops. Amongst patients with cardiovascular (CV) disease, ID is common and is associated with worse symptoms, poorer quality of life, and a worse prognosis. However, the criteria used to define ID in studies and international guidelines are inconsistent and lack universal acceptance. Accordingly, we review the various criteria used to define ID in patients with CV disease, discuss how these might have influenced the results of observational studies and randomized trials and suggest areas for future research.