The current World Health Organization (WHO) guidelines, based on expert opinion with low-grade evidence, define iron deficiency in healthy blood donors to be <15 mg/L serum ferritin. A new study recently published developed a method to physiologically identify serum ferritin thresholds for iron deficiency in women. Serum ferritin concentrations usually correlate with total body iron stores. The study authors utilized the Retrovirus Epidemiology Donor Study-II Donor Iron Status Evaluation (REDS-RISE) samples and hypothesized that iron deficient erythropoiesis starts when the serum ferritin concentration falls below a threshold at which the concentrations of soluble transferrin receptor (sTfR) begins to increase and hemoglobin (Hb) then decreases. Baseline sTfR and Hb concentrations were measured in 286 first time or reactivated female donors (20-49 years) from six U.S. blood donation centers. Data from both sTfR and Hb suggest a serum ferritin threshold level of <25 mg/L to indicate iron-deficiency erythropoiesis. Thresholds calculated from 5442 women from the U.S. National Health and Nutrition Examination Survey (NHANES) found a similar threshold. International comparisons are needed, but these results suggest that the WHO guidelines for serum ferritin levels for iron deficiency may be too low for female blood donors.
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