Interferon-induced thyroid dysfunction--not always transient

Thyroid dysfunction in Turkish patients with chronic hepatitis C receiving peginterferon plus ribavirin in the period of 2005-2010

Interferon-α based therapy for chronic hepatitis C (CHC) is associated with thyroiditis and thyroid dysfunction (TD). This study investigated whether TD during pegylated interferon-α (PEG-IFN) plus ribavirin treatment favors sustained viral response (SVR), and also the association between TD and PEG-IFN formulations. This retrospective study was performed in CHC patients who had received PEG-IFN plus ribavirin and had been followed for six months after treatment. Several factors were compared between patients with and without TD. 119 patients were included in the study. De novo incidence of TD was found to be 16.8%, and 16 of the 18 patients with TD achieved SVR. Although this rate was higher than patients without TD according to univariate analysis, logistic regression analysis revealed that there was not a significant association between TD and SVR, whereas baseline thyroperoxidase antibody (anti-TPO) positivity was the only significant predictor of TD. Moreover, TD was not associated with PEG-IFN type. Both interferon-α and hepatitis C virus (HCV) contribute to TD during antiviral therapy. It seems that there is no association between thyroid toxicity and viral clearance or type of PEG-IFN; however, anti-TPO positivity before treatment is the strongest predictor for TD during antiviral therapy.

The natural history of interferon-α induced thyroiditis in chronic hepatitis c patients: a long term study

BACKGROUND

Autoimmune thyroid disease is a common complication of patients with chronic hepatitis C undergoing combination pegylated interferon-α and ribavirin treatment. A small proportion develops interferon-induced thyroiditis of which the long term natural history is unknown and how it compares with de novo thyroiditis. The aim of the study is to determine the natural history of thyroid disease including antibody profile in this particular setting 36 months from the completion of therapy.

METHODS

A cohort of 18 hepatitis C patients (mean age 45 ± 8 years (standard deviation)) who developed exclusively thyroiditis in this setting was followed every 12 months after the completion of therapy for 36 months. Investigations included thyrotropin, free tetra-iodothyronine, free tri-iodothyronine levels and thyroid autoantibodies.

RESULTS

None of the patients developed any long term thyroid disease. Two patients had a prolonged hypothyroid phase of the thyroiditis early after the completion of treatment but recovered fully. The remaining 16 patients remained euthyroid. Similarly, thyroid autoantibodies all declined and returned to reference range.

CONCLUSIONS

The long term natural history in this small series of interferon induced thyroiditis was benign. If a larger series confirms a similar outcome then there is no long term residual effect on thyroid function and follow-up testing would not be warranted.

Individualisation of antiviral therapy for chronic hepatitis C

The combination of pegylated-interferon (PEG-IFN)/ribavirin is currently the standard of care antiviral treatment for chronic hepatitis C (CHC), but optimal results require an individual approach. Key issues are to deliver doses that confer optimal antiviral efficacy against hepatitis C virus (HCV) for a time sufficient to minimise relapse. Viral monitoring during therapy guides the subsequent treatment course, particularly HCV RNA results at 4 weeks (rapid viral response [RVR]) and 12 weeks (complete early viral response [cEVR]). There is strong evidence that for most patients with genotypes 2 or 3 HCV infection, RVR allows truncation of treatment to 16 weeks, provided ribavirin dose is weight-based. However, those patients with cirrhosis, insulin resistance/diabetes or older than 50 years need 6-12 months treatment. For "difficult-to-treat" CHC (genotypes 1 and 4), RVR is infrequent (approximately 15% in European studies), but allows treatment to be truncated from 48 to 24 weeks. Without RVR, there is some evidence that longer treatment (72 weeks) improves sustained viral response (SVR). However, "induction dosing" first 12 weeks of PEG-IFN clearly does not improve SVR. To prevent dose reductions and complete therapy, it is critical to detect and treat depression and other disabling side-effects, including judicious use of growth factors for severe anemia or neutropenia and possibly, thrombocytopenia. Another potentially important aspect may be attempts to counter central obesity and insulin resistance, which confer suboptimal antiviral response with any HCV genotype. Treatment partnerships with specialist nurses, psychological therapists and other healthcare workers are also essential for optimal individual management of patients with CHC.