Transient Elastography May Predict Liver Iron Overload in Adult Thalassaemia Patients

Abstract

Although it is life saving, transfusion therapy has resulted in the majority of thalassemia patients being at risk for hemosiderosis-induced organ damage. Liver Iron Concentration (LIC) assessed by liver biopsy is considered the most accurate and sensitive method for determining body iron burden in patients with iron overload. The development of liver fibrosis is more closely related to liver iron concentration. Transient elastography (FibroScan, FS), which measures liver stiffness (LS), is a novel, noninvasive method to assess liver fibrosis. Whether FS is useful in the detection of preexisting liver iron overload in patients presenting with thalassaemia major without chronic viral hepatitis, is unclear. On the other hand, Magnetic Resonance Imaging (MRI) is a relatively inexpensive, widely available but more time consuming method that has long been considered as a useful tool for the non-invasive estimation of tissue iron content in multiple transfused patients with thalassemia.Aim: To study the prevalence and severity of liver fibrosis of transfusion dependent thalassaemia major patients, and correlate the MRI.LIC with the measurements of FS.Methods-Patients: The applicability for FS (Echosens, Paris, France) was defined as at least 10 valid measures and a success rate (number of valid measures/total number of LS Measures, LSM) ≥60% and a ratio of interquartile range/stiffness ≤0,2. Most subjects with FS scores below 5.1 kilopascals (kPa) are considered to have minimal fibrosis (grade F0 or F1, METAVIR score) according to the literature. The cut off FS values for diagnosing different stages of hepatic fibrosis were defined as > 7.9kPa for F≥2, > 10.3kPa for F≥3 and > 11.9kPa for F=4. A total of 43 thalassaemic patients 23 males/20 females, median age 26,8±4,9 years, regularly transfused (pre-transfusion haemoglobin 9,7g/dl) were included in the study. All patients were hepatitis C virus (HCV) negative and chelated with different drugs (13 on deferasirox, 12 on deferiprone, 5 on desferrioxamine and 13 on combined therapy). Median ferritin levels were 1552±1576ng/ml. Liver tests (AST, ALT, γGT and Alkaline Phosphatase) were done simultaneously to all patients. Twenty-two of the 43 patients underwent liver iron determination (LIC) simultaneously by two methods: T2* Magnetic Imaging (T2*MRI) assessment and by calculation of MR-Hepatic Iron Concentration (MR.HIC) values (based on an algorithm developed by Gandon et al (Lancet 2004), using liver to muscle ratios in five axial gradient-echo sequences). T-test was used in statistical analysis to compare means.Results: Applicability of LSM was 100%. Overall median LSM was 8,25±6,05kPa (range 4–40,3kPa). Nineteen (44,1%) patients had FS<6,1kPa (notably 8/19 patients below 5,1kPa), 13 (30,2%) had <7,9kPa, 4 (9,3%) had <10,3kPa, 2 (4,7%) had <11,9kPa and 5 (11,7%) above 11,9kPa. Total FS correlated with Ferritin (r=0,39, p=0,008). Using the cutt-off value of 6,1 kPa for FS measurements, patients were divided in two groups with different ferritin levels: A (<6,1kPa) 1039±758ng/ml vs B (>6,1kPa) 1833±1742ng/ml, p<0,03. FS values of the three different major therapy groups did not differ significantly. FS (22pts) correlated negatively with T2*MRI results (r=−0,39, p=0,07) and positively with MR.HIC results (r=0,49, p=0,02). There was no correlation with liver function tests.Conclusions: Severe haemosiderosis and hepatic fibrosis are common in patients with thalassaemia major despite the use of chelation therapy and the absence of HCV. Elastography has several characteristics that make it a desirable method for assessing hepatic fibrosis. In addition to being noninvasive and painless, it is also quick, inexpensive, and produces consistent results. It can also be useful as an alternative to check for liver iron overload, as abnormal results predict heavy liver iron overload. Further longitudinal and prospective studies are necessary to confirm these preliminary data.