Serum Ferritin and Liver Iron Concentration in Patients with Iron Overload.

Despite its limitations, serum ferritin (SF) is commonly used to monitor chelation therapy in primary and secondary hemochromatosis. To better predict liver iron concentration (LIC), we prospectively investigated the relationship between SF and LIC in a total of 421 patients with primary (HFE-1 associated, n=241) or secondary hemochromatosis (n=180), consisting of chronically transfused thalassemia (Tx-Thal: n=89) or sickle cell disease patients (Tx-SCD: n=45) and transfusion independent thalassemia patients (nTx-Thal: n=26). In all patients, LIC was measured by SQUID biosusceptometry. SF correlated with LIC (R_S = 0.51–0.83, p < 0.001) but was a poor predictor for LIC. SF was significantly lower (p < 0.001) in nTx-Thal and HFE-1 patients despite similar LIC (421 – 5524 μg/g-liver) and it was higher in Tx-SCD compared to Tx-Thal (p = 0.03). In order to improve the value of SF, we calculated the SF/LIC ratio for each group. SF/LIC remained stable over time in patients whose therapy did not change. In iron loaded patients without blood transfusion therapy (nTx-Thal and HFE-1), the median SF/LIC ratio was significant lower (0.32 and 0.43) as compared to transfused patients (Tx-Thal: 0.87, HCV-Thal: 0.99, Tx-SCD: 1.2), probably, indicating differences in the secretion of ferritin into plasma. We conclude that SF alone can mislead the iron unloading therapy as it underestimates LIC in nTx-Thal patients and overestimates LIC in Tx-SCD patients. Once the initial LIC value is obtained and the individual SF/LIC ratio is determined in a patient, the ratio together with SF may be more useful than SF alone to monitor iron overload and predict LIC.