The Correlation Of Hepatic Iron Loading Determined By Magnetic Resonance Image and Serum Ferritin In Patients With Beta-Thalassemia Intermedia

Current practice of starting iron chelation when ferritin values reach 1,000 mcg/l has been given to patients with thalassemia disease. The body iron load in patients with thalassemia intemedia can be different from other severe thalassemia disease due to the increased intestinal iron absorption.

The correlation of hepatic iron loading determined by magnetic resonance image study (MRI) and various parameters was calculated.

MRI study, using CRMtool to determine the myocardial and hepatic iron loading, was performed in pediatric patients with beta-thalassemia intermedia. The amount of blood transfusion and duration of iron chelation were recorded. The levels of serum ferritin as well as the transfusion-transmitted diseases were checked twice yearly.

In all, 40 patients (19 males, 23 females) manifested as beta-thalassemia intermedia were enrolled in the study. They included beta thalassemia/HbE disease (n=37) and beta thalassemia major (n=3) with the mean age of 14.9±3.6 years. Three patients with beta-thalassemia major behaved as beta-thalassemia intermedia since two patients carried the combination of beta-thalassemia⁰ and beta-thalassemia⁺ genes while another patient had an additional alpha-thalassemia gene. The remaining patients possessed the combination of beta-thalassemia genes at codon 41/42 (4 base pair deletion) and HbE gene at codon 26 (GAG>AAG). All patients received routine hepatitis B vaccination. None had positive serological testing for HBsAg, antiHCV or antiHIV. They required regular transfusion to maintain their pre-transfusion hematocrit at 24% starting at the mean age of 4.1±3.3 years with the mean duration of 10.1±4.6 years. Nineteen were splenectomized at the mean age of 8.0±3.1 years. They all received iron chelation of 10-12 hours of desferrioxamine subcutaneous injection, oral deferiprone ingestion or the combination of desferrioxamine and deferiprone starting at the mean age of 9.1±3.8 years with the mean duration of 6.2 ±4.3 years. At the mean age of 14.9±3.6 years, they underwent MRI study and revealed that the mean T2* of myocardium was 38.6±8.1 milliseconds (ms) and mean T2* of liver was 3.2±2.0 ms. Neither patients had myocardial iron loading while 36 patients had hepatic iron loading varying from severe degree of <1.4 ms (iron >10 mg/g dry weight, n=4), moderate degree of >1.4-2.7 ms (iron >5-10 mg/g dry weight, n=16) and mild degree of >2.7-6.3 ms (iron 2-5 mg/g dry weight, n=16). The results revealed no correlation of the hepatic T2* and the duration of blood transfusion (p=0.157), duration of iron chelation (p=0.071), total blood transfusion and total iron loading from transfusion (p=0.471) one-year blood transfusion and one-year iron loading from transfusion (p=0.321) except for the serum ferritin (p=0.001). The geographic mean of ferritin was 1584.9 mcg/l. The hepatic iron loading by MRI was shown in the equation of T2*(ms) = 4.663-0.001ferritin (mcg/l) (r=-0.503, p=0.001). Patients with serum ferritin ≥1,000 mcg/l risked hepatic iron loading (T2*<2.7 ms, iron 5-10 mcg/g dry weight) with an odds ratio of 5.07 (95% CI 1.09-23.44). Therefore, patients with beta-thalassemia intermedia were at risk of hepatic iron overloading if the initiation of iron chelation started at the serum ferritin of 1,000 mcg/l.

The current practice of starting iron chelation when ferritin values reach 1,000 mcg/l risks hepatic iron loading in patients with beta-thalassemia intermedia. Advanced technology for evaluating hepatic iron loading is suggested. Thus, where MRI study is not feasible, serum ferritin can be used to estimate the hepatic T2*.

No relevant conflicts of interest to declare.