RESUMEN
The long-term impact, incidence and risk factors of thyroid dysfunction in chronic hepatitis B (CHB) patients receiving pegylated interferon (IFN) alpha (PegIFN-alpha) therapy remain unclear. We aim to investigate the long-term safety of thyroid dysfunction in CHB patients receiving PegIFN-alpha. A retrospective observational study of 425 CHB patients with normal baseline thyroid function was carried out. Patients were followed up over 10 years to assess thyroid function after receiving IFN. At the end of the IFN therapy, 67 patients (15.8%) had developed thyroid dysfunction, 31 patients (46.3%) had hyperthyroidism and 64.4% presented with subclinical thyroid dysfunction. In follow-up of thyroid dysfunction patients, 37 patients (74.0%) spontaneously regained normal thyroid function. Pretreatment thyroid-stimulating hormone (TSH) level, thyroid peroxidase antibody (TPOAb) positivity and free thyroxine (FT4) were independent risk factors associated with thyroid dysfunction incidence. High TSH level (OR = 9.866, 95%CI, 3.245-29.998) was associated with a greater likelihood of hypothyroidism. High FT4 levels (OR = 0.464, 95%CI, 0.248-0.868) indicate a low likelihood of thyroid dysfunction. Thyroid dysfunction is a common but acceptable side effect of IFN therapy for CHB. Most thyroid dysfunction is reversible. Pretreatment TSH level and TPOAb positivity are risk factors for thyroid dysfunction development during IFN therapy. A high TSH level predicts an increased incidence of hypothyroidism. Moreover, FT4 may be a protective factor for thyroid dysfunction.