Association of Circulatory Iron Deficiency With an Enlarged Heart in Patients With End-Stage Kidney Disease

Objectives: High prevalence of iron deficiency (ID) and cardiomyopathy have been observed in patients with end-stage kidney disease (ESKD). Our objective was to clarify associations between ID and cardiac remodeling in patients with ESKD. Design and Methods: A cross-sectional study was conducted using 1974 Japanese patients with ESKD at the initiation of maintenance dialysis. Levels of hemoglobin (Hb), iron status, and cardiac enlargement as assessed by the cardiothoracic ratio (CTR) were determined immediately before the first hemodialysis session. Circulatory ID was defined as transferrin saturation (TSAT) < 20%, and stored ID was defined as ferritin level <100 ng/dL. Results: The mean age was 67 years. Median CTR was 54.0%. The prevalence of circulatory and stored ID was found to be 38% and 34%, respectively. CTR was higher in patients with circulatory ID than in those without. Even in ESKD patients without overhydration, significant negative association was observed between TSAT and CTR. Higher odds ratios in parallel with higher CTR categories compared with the reference category of CTR <45% were found in patients with TSAT <20% on multinomial analysis, but ferritin did not show any significant associations. The odds ratio for CTR >54% showed an upward trend in patients with TSAT <20% (odds ratio: 1.3) and <10% (odds ratio: 1.6) compared with the reference, even after adjusting for confounding variables such as Hb and ferritin. However, that phenomenon was eliminated by adding usage of an iron agent. Conclusions: Circulatory ID is closely associated with an enlarged heart independent of ferritin and Hb. Iron supplementation in the predialysis phase of chronic kidney disease may prevent cardiac remodeling independent of Hb level in patients chronic kidney disease.