2026 年 5 巻 3 号 p. 109-121
Background: The utility of red blood cell (RBC) indices for iron deficiency in patients with chronic kidney disease (CKD) remains unclear. This study aimed to compare RBC indices, including mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and red blood cell distribution width (RDW), across estimated glomerular filtration rate (eGFR) categories and evaluate their utility in assessing low-ferritin anemia.
Methods: Data were extracted from the Abbott Diagnostic Support System at the Nihon University Itabashi Hospital. The dataset included 756,146 samples from patients ≥ 18 years of age with simultaneous hemoglobin (Hb) and eGFR measurements. The ferritin levels were measured in 43,165 samples (5.7%). The RBC indices were classified according to the ferritin levels ( < 20, < 100, and ≥ 200 ng/mL) and compared between the low eGFR ( < 30 mL/min/1.73 m2) and normal eGFR ( ≥ 60 mL/min/1.73 m2) groups.
Results: Lower eGFR categories were associated with a higher proportion of samples with low hemoglobin levels. In samples with low-ferritin anemia (ferritin < 20 ng/mL and Hb < 10 g/dL), MCV < 80 fL was observed in 51.9% of the normal eGFR group, but only 11.8% of the low eGFR group. MCH < 25.0 pg was observed in 59.4% of patients with a normal eGFR and 18.0% of those with low eGFR. RDW did not correlate markedly with ferritin levels in the low eGFR group.
Conclusion: In patients with low eGFR, anemia with low ferritin levels was not associated with typical RBC indices that suggest iron deficiency. RBC indices should be interpreted cautiously when assessing iron deficiency in patients with low eGFR.
