Diagnostic accuracy of serum hepcidin for iron deficiency in critically ill patients with anemia

PURPOSE: Inflammation-induced anemia is frequent among critically ill patients and can be aggravated by true iron deficiency (ID) resulting from blood losses. The serum hepcidin level controls the availability of iron for erythropoiesis, and its determination offers new perspectives for the diagnosis of ID in the presence of inflammation. We conducted a prospective observational study to determine the cutoff value and diagnostic accuracy of hepcidin levels for detecting ID in critically ill anemic patients. METHODS: Patients suffering from anemia (hemoglobin <100 g/l) and expected to stay for more than 7 days in intensive care had weekly determinations of hematological and iron parameters, including hepcidin levels (ELISA test). The iron status for each set of measures was determined by the consensus of three experts, blinded to hepcidin values. RESULTS: Of 51 patients (36 male/15 female), 5 had ID at inclusion, while 8 developed ID during their stay. A total of 128 iron profiles were analyzed. Median hepcidin levels were 80.5 (0.05-548.3) and 526.6 (246.7-891.4) microg/l for ID and non-ID profiles, respectively. The onset of ID during the ICU stay led to a progressive decline in hepcidin levels, whereas a persistent inflammatory profile remained associated with high hepcidin concentrations. The optimal threshold for serum hepcidin for ID diagnosis was assessed by building 100 ROC curves using a resampling method and found at 129.5 microg/l [95% CI = (115.5-143.4)]. CONCLUSIONS: Hepcidin levels may be suppressed by ID even in case of inflammation. Serum hepcidin of 129.5 microg/l was the most accurate threshold for ID diagnosis in critically ill patients with anemia.