Sierpinski R, Josiak K, Suchocki T, et al. - The present study was conducted to ascertain the iron biomarker with the greatest accuracy for the diagnosis of iron deficiency (ID) in bone marrow in patients with ischaemic heart failure (HF), and to construct the prevalence of ID using this biomarker and its prognostic value in HF patients. Researchers included a total of 791 individuals with HF with a left ventricular ejection fraction≤ 45% and were prospectively followed up for 3 years. They evaluated serum ferritin, transferrin saturation, soluble transferrin receptor (sTfR) as iron biomarkers. It was shown that in patients with HF, high serum sTfR accurately reflects depleted iron stores in bone marrow, and identifies those with high 3‐year mortality.