Study on the Threshold of Serum Ferritin Required for Erythropoiesis and Iron Sufficiency in Hemodialysis Patients

Serum ferritin (Ft) reflects total body iron stores and serves as a reference indicator for iron supplementation. However, optimal Ft level remains unclear in hemodialysis (HD) patients. We previously reported that total body iron (TBI), a novel index defined as the sum of red blood cell iron and storage iron, increases during oral iron replacement therapy (OIRT) and remains stable once iron sufficiency is achieved. In this study, we analyzed data from 100 OIRT courses in 79 maintenance HD patients. We examined the relationship between changes in hemoglobin (Hb) and Ft (⊿Hb, ⊿Ft) at 4 and 7 months after the initiation of OIRT, during which TBI remained stable, to determine the Ft level required for erythropoiesis. At 7 months, compared with 4 months, mean Hb significantly decreased by 0.2 g/dL (p = 0.03), while median Ft significantly increased from 60 to 75.0 ng/mL (p < 0.01). After adjustment for TBI, a significant inverse relationship was observed between ⊿Hb and ⊿Ft (β = −35.9, 95% CI −40.1 to −31.7, p < 0.001). These results indicate that an increase of 1 g/dL in Hb requires approximately 30–40 ng/mL of Ft, suggesting that this threshold may be useful for guiding iron supplementation in the treatment of anemia.