Magnetic Resonance Imaging Versus Serum Iron Status as Diagnostic Tools for Pituitary Iron Overload in Children with Beta Thalassemia

Background: Thalassemia is a common genetic disorder associated with endocrine disorders. Iron deposition may start in the anterior pituitary gland, but clinical signs are usually not evident until puberty. Aim of the study was to evaluate pituitary iron overload in children with β thalassemia using MRI T2* and correlate MRI T2* and biochemical markers of iron overload with pituitary hormones.

Patients and Methods: This study was carried out on 30 children with β-thalassemia major (19 females and 11 males ) with their age ranging from 10 - 18 years and mean age value of 12.8 ± 2.4 and 30 healthy children of matched age and sex as controls in the period from September 2018 to September 2019. For all patients the following were done: complete clinical evaluation including anthropometric data and Tanner staging, laboratory investigations including serum iron status, thyroid function, basal and growth hormone provocation test by clonidine, Follicle stimulating hormone (FSH) , Luteinizing hormone (LH) , and pituitary MRI T2*.

Results: Weight, Z score of weight, height, Z score of height and Body mass index (BMI) were found significantly lower in patients compared with controls. Patients had delayed puberty compared with controls. Pituitary MRI T2* was found significantly lower in patients compared with controls (P=0.001). FSH, LH, and provocative growth hormone levels were found significantly lower in patients compared to controls (p <0.001). Serum ferritin & iron were found significantly higher in patients than controls (P<0.001). Significant negative correlations were found between serum ferritin and Weight, Height, Z score of Weight, Z score of Height, BMI and pituitary hormones. Significant negative correlations were found between Pituitary MRI T2* and serum ferritin. Significant positive correlations were found between Pituitary MRI T2* and Weight, Height, Z score of Weight, Z score of Height and pituitary hormons. The pituitary T2* carried the sensitivity of 80% ,100% and 100% and specificity of 70% ,83.3% and 100% for predicting GH hormone abnormality, LH and FSH respecetively.

Conclusions: There were a significant positive correlations between pituitary MRI T2*and anthropometric measurement and pituitary hormones of studied patients. There was a significant negative correlation between Pituitary T2* and serum ferritin. Pituitary iron overload can be detected by MRI T2* which is a diagnostic tool in detecting pituitary iron overload with subsequent effect on hormonal secretion especially growth hormone.

Recommendations: Children with thalassemia should undergo meticulous follow up regarding regular blood transfusion, regular iron chelators in a proper manner and doses and routine use of MRI T2* in the evaluation of pituitary iron overload before irreversible damage occur in the pituitary gland.