Liver Fibrosis and Tissue Iron Accumulation in Patients on Hemodialysis: A Study Based on Quantitative MRI

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Background: Intravenous iron supplementation is essential for treating anemia in patients on hemodialysis, with recent clinical guidelines allowing higher serum ferritin thresholds. A prior study showed reduction in mortality with this approach, yet the issue of iron body deposition has not been fully investigated. In this cross-sectional study, we assessed tissue iron levels and liver fibrosis using quantitative magnetic resonance imaging (qMRI) in patients on maintenance hemodialysis. Methods: Tissue iron levels in the liver, bone (iliac crest - IC and vertebral body - VB), and spleen were assessed using 3T MRI with a multi-echo gradient echo sequence, allowing measurement of water R2* for tissue iron estimation separate from fat. Liver fibrosis was also assessed via a multi-echo spin echo sequence and multi-component relaxometry. Hemodialysis patients (n = 43) were stratified into tertiles based on liver water R2* (R2*W) values and compared to healthy volunteers (control group; n= 10). Clinical, demographic, and laboratory data were collected for all participants. Results: Median [25th, 75th] serum ferritin levels were higher in the third tertile (152 [83, 218]; 259 [131,349]; 167 [113, 518]; and 542 [349, 674] ng/mL in control, 1st, 2nd, and 3rd tertile, respectively, p<0.001). Of note, only 3 patients had ferritin levels > 700 ng/mL. MRI-derived iron levels in the IC, VB, and spleen were higher in the third tertile compared to other groups (p<0.05). Liver fibrosis was also higher in the third tertile (p<0.001) and correlated with liver R2*W (R=0.613, p<0.01). Liver R2*W correlated with tissue iron (VB [R=0.703], IC [R=0.432] and spleen [R=0.830] R2*W, p<0.05 for all). Liver fibrosis also correlated with tissue iron (VB [R=0.451], IC [R=0.361] and spleen [R=0.559] R2*W, p<0.05 for all). Conclusion: In patients on hemodialysis, higher serum ferritin levels — albeit within the KDIGO reference range — were associated with liver fibrosis and increased iron deposition in the liver, bone, and spleen. Our findings raise concerns about potential tissue iron overload and highlight the need for careful monitoring of iron stores, suggesting that MRI-based tissue iron assessment may be a valuable tool in guiding iron supplementation strategies in this population.

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