Correlation of Serum Ferritin Levels and Liver Iron Concentration Determined by R2* MRI in Patients with Thalassemia Intermedia.

Abstract

Background: Unlike patients with thalassemia major (TM), those with thalassemia intermedia (TI) do not require regular blood transfusion therapy but remain susceptible to iron overload due to increased intestinal iron uptake triggered by ineffective erythropoiesis. TI patients can accumulate 1–3.5 g of excess iron per year, and effective monitoring of iron burden is an important element of patient management. Assessment of serum ferritin (SF) levels is a convenient and widely used method, and a correlation between SF and liver iron concentration (LIC) has been demonstrated in patients with TM. SF levels may, however, be a poor indicator of LIC in patients with TI and the limited data available on the SF:LIC correlation prove equivocal; in fact, reports suggest a discrepancy between LIC and SF in patients with TI. This is the largest study to use R2* MRI to evaluate the SF:LIC correlation in patients with TI.Methods: This was a cross-sectional study of randomly selected, infrequently/non-transfused TI patients treated at a chronic care center in Hazmieh, Lebanon. Patient charts were reviewed and a medical history was compiled. Blood samples were taken for SF assessment, and LIC was determined by R2* MRI.Results: Data from 74 TI patients were included in this analysis (33 male, 41 female; mean age 26.5 ± 11.5 years). Of this group, 59 (79.7%) patients were splenectomized, 20 were transfusion-naive, 45 had received several transfusions in their lifetime but none in the past year, and 9 patients were regularly transfused 2–4 times per year. Overall mean SF values were 1023 ± 780 ng/mL (range 15–4140); mean LIC levels were 9.0 ± 7.4 mg Fe/g dry weight [dw] (range 0.5–32.1). In contrast to previous findings, a significant positive correlation between mean LIC and SF values was seen in the whole group (R=0.64; P<0.001), and in a subset of splenectomized patients (R=0.62; P<0.001). In comparison with data obtained from a randomly selected group of patients with TM treated at the center, SF levels in TI were seen to be significantly lower, while the mean LIC values were similar in both groups of TI and TM. For a given LIC, SF values were lower in patients with TI than those with TM (Figure).Conclusions: Evaluation of iron levels shows that many patients with TI have SF and LIC levels above the recommended threshold levels, indicating a risk of significant morbidity/mortality. Similar to TM, a significant correlation between SF and LIC was observed in patients with TI; however, the relationship between SF and LIC was different between TI and TM (for the same LIC, the SF values in TI were lower than those in TM). Therefore, use of the current threshold for iron overload based on SF values in TM will lead to significant underestimation of the severity of iron overload in patients with TI. This may result in delayed chelation therapy, and expose patients to morbidity and mortality risks associated with iron overload. Disease-specific management approaches are therefore required in patients with TI. This includes either regular assessments of LIC, ideally by non-invasive R2* MRI, or lowering the SF threshold for initiating iron chelation in patients with TI. [Display omitted]