Relationship between bone marrow iron load and liver iron concentration in dialysis-associated haemosiderosis

Iron overload due to the excessive use of parenteral iron in haemodialysis is now an increasingly recognised clinical issue. Before erythropoiesis-stimulating agents (ESA) were introduced, a specific feature of patients treated by dialysis and having iron overload was that iron levels in the bone marrow were paradoxically low in most of them, despite severe hepatosplenic siderosis. Whether or not this paradox persists in the actual ESA era was unknown until recently, when an autopsy study in 21 patients treated by haemodialysis revealed similarities between liver and bone marrow iron content. The aim of this study was to further explore these recent findings in a cohort of alive patients on dialysis and to analyse the determinants of iron bone marrow.

Liver iron concentration (LIC) and vertebral T2^∗ (a surrogate marker of bone marrow iron) were analysed retrospectively in 152 alive patients on dialysis (38.8% female) of whom 47.4% had iron overload by quantitative magnetic resonance imaging (MRI).

Vertebral T2^∗ differed significantly between patients classified according to liver iron content at MRI: those with mild or moderate and severe liver iron overload had increased vertebral iron content at R2^∗ relaxometry MRI (mild: vertebral T2^∗ = 9.9 ms (4-24.8); moderate and severe: vertebral T2^∗ = 8.5 ms (4.9-22.8)) when compared to patients with normal LIC (vertebral T2^∗ = 13.2 ms (6.6-30.5) (p < 0.0001 Kruskal-Wallis test)).

The paradoxical discrepancy between bone marrow and liver iron-storage compartments observed in the pre-ESA era has disappeared today, as shown by a recent autopsy study and the present study in a cohort of alive patients treated by dialysis.

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