Bone marrow macrophage iron content and sideroblast count in iron- and ESA-naive patients with CKD-related anemia

Background Since in chronic kidney disease (CKD) iron deficiency anemia (IDA) can coexist with inflammation-induced immobilization of iron in macrophages (anemia of chronic disorders - ACD), we assessed the utility of ferritin, transferrin saturation (TSAT), and hepcidin for differentiation of mixed IDA-ACD from ACD, using bone marrow (BM) examination as reference. Methods This cross-sectional, single-center study analyzed 162 non-dialysis iron and epoietin-naive CKD patients (52% males, median age 67 years, eGFR 14.2 mL/min 1.73 m(2), hemoglobin 9.4 g/dL). BM aspiration, serum hepcidin (ELISA), ferritin, TSAT, and C-Reactive protein (CRP) were the main studied parameters. Results ACD was seen in 51%, IDA-ACD in 40%, while pure IDA in only 9%. In univariate and binomial analyses, IDA-ACD differed from ACD by lower ferritin and TSAT, but not by hepcidin or CRP. Correspondingly, in receiver operating curve analysis, ferritin and TSAT differentiated IDA-ACD from ACD, at cutoffs of 165 ng/mL and 14%, but with moderate precision (sensitivity and specificity of 72%, and 61%, respectively). Conclusion The mixed pattern IDA-ACD could be more prevalent than estimated in non-dialysis CKD. Ferritin and, to a lesser degree, TSAT are useful in the diagnosis of IDA superimposed on ACD, while hepcidin, although reflecting BM macrophages iron, seems to have limited utility.

Automated summary

This study found that iron deficiency anemia (IDA) and anemia of chronic disorders (ACD) can coexist in patients with chronic kidney disease (CKD), and ferritin and transferrin saturation (TSAT) are useful markers for differentiating IDA-ACD from ACD, while hepcidin, a marker of iron in bone marrow macrophages, has limited utility.