Physiologically based serum hepcidin and ferritin thresholds identify similar onsets of iron-deficient erythropoiesis in adult blood donors.

To compare physiologically based serum hepcidin and ferritin thresholds for iron deficiency in adult female and male blood donors, we analysed laboratory results obtained during screening for a blood donor study. In 907 apparently healthy blood donors, we examined the relationships of hepcidin and ferritin with five indicators of the onset of iron-deficient red blood cell production: haemoglobin (Hb), soluble transferrin receptor (sTfR), erythrocyte zinc protoporphyrin (ZPP), reticulocyte haemoglobin content (Retic-Hb) and mean corpuscular volume (MCV). Serum hepcidin and ferritin were correlated (Pearson's r = 0.69, p = <0.001 females; r = 0.65, p < 0.001, males). At lower serum hepcidin and ferritin concentrations, Hb, Retic-Hb and MCV decreased and sTfR and ZPP increased. Using restricted cubic spline models, the hepcidin thresholds for iron deficiency in adult female donors 18-49 years, 50-75 years and all male blood donors 18-75 years old were 13.9, 24.8 and 28.8 μg/L respectively. The corresponding ferritin thresholds were 25.4, 30.7 and 32.5 μg/L respectively. Among blood donors 18-50 years old, serum hepcidin and ferritin thresholds for iron deficiency were lower in women than in men but were similar after 50 years of age. In conclusion, among adult blood donors, serum hepcidin and ferritin thresholds are similarly effective for detecting iron deficiency, especially among women.