Beverborg NG, et al. - In patients with heart failure (HF), researchers defined and characterized similarities and differences between low iron storage (LIS)—defined as a bone marrow-validated combination of transferrin saturation less than 20% and a serum ferritin concentration of 128 ng/mL or less—and defective iron utilization (DIU)— defined as transferrin saturation less than 20% and a serum ferritin concentration greater than 128 ng/mL. Data from 2 prospective observational studies was used for this analysis. In HF patients, both LIS and DIU were prevalent and had a distinct clinical profile. A higher proportion of anemia and a worse quality of life characterized low iron storage, while increased levels of various inflammatory markers characterized DIU. An impaired 6-minute walking test was seen in both. There was an independent association between the composite end point of all-cause mortality or HF hospitalizations and LIS, but not with DIU.