The Cutoff of Ferritin for Evaluation of Hypothyroidism in Patients With Thalassemia

Abstract

Background: Thalassemia major is a genetic disease with a recessive autosomal pattern of inheritance that occurs as a result of disorder in hemoglobin synthesis. Researchers aimed to investigate the cutoff of ferritin for the development of hypothyroidism in patients with thalassemia major.

Materials and methods: This was a retrospective analytic cross-sectional study that was conducted on the medical records of patients with thalassemia major. Overt hypothyroidism was defined as thyroid stimulating hormone (TSH) level of >6.5 mIU/L and T4 level of < 4.2 ng/dL and subclinical hypothyroidism was defined as TSH level of >6.5 mIU/L and T4 level of >4.2 ng/dL. Data were gathered by a form including age, sex, weight, height, body mass index, thyroid test results, and the mean of last 3 consecutive hemoglobin and ferritin levels.

Results: In this study, 67 patients were evaluated. The mean age of the participants was 15.37±3.73 years. The frequency of subclinical hypothyroidism was 10.4%, and no cases of clinical hypothyroidism were noted as well as secondary hypothyroidism. Although there was a significant linear correlation between mean ferritin level and TSH (P=0.008), no significant correlation was noted between levels of ferritin and T4 levels. As ferritin was significantly correlated with TSH, the results showed that the mean serum level of ferritin in β-thalassemia major patients with hypothyroidism was higher than that in β-thalassemia major patients with normal thyroid status (P=0.013). The cutoff point for ferritin was 1953 ng/mL (sensitivity=85.7%, specificity=60%).

Conclusion: It seems that considering the development of hypothyroidism by reaching the ferritin cutoff point, intensification of the iron chelation regimen along with a shorter interval for laboratory endocrine examinations can be recommended.