Endocrine Abstracts

Interferon alpha (IFNα) and Ribavirin combination therapy effectively eradicates Hepatitis C Virus (HCV) in up to 80% of patients. Transient thyroid dysfunction (TD) (>80% hypothyroidism) usually due to a destructive thyroiditis has been recognised to occur in up to 25% of patients treated in Italy, Japan and Australia. However, data are lacking in a UK cohort and no standardised protocol for testing of thyroid function testing exists. The aim of this study was to determine the prevalence of TD in 275 patients who received IFN therapy for HCV from January 2006–June 2008 in a tertiary referral centre and provide a future strategy for detection and management of TD.

Thyroid function, viral load, HCV genotypes, and liver function were assessed during a 6–12 month course of combination therapy. If TSH <0.1 mU/l and raised FT4, a thyroid diagnostic isotope scan was performed. Of the 275 patients (183 men, 92 women), 20% (n=56; 15% of men, 32% of women) developed TD within 1–11 months of commencing IFN. In the total cohort, 9% (n=24) developed an initially suppressed TSH (1% Graves, 8% transient thyroiditis). Twelve percent (n=32) of the sample developed an initially elevated TSH (2% permanent hypothyroidism requiring thyroxine therapy, 10% transient hypothyroidism). The mean TSH at baseline was 2.81 mU/l in those who developed hypothyroidism compared to 1.51 mU/l in the subjects in whom no TD was documented.

This study has found a higher than expected prevalence of hyperthyroidism in this cohort. A baseline serum TSH greater than 2 mU/l predicted a higher risk of development of hypothyroidism. The Hepatitis Specialist Nurse team monitored thyroid function tests monthly during treatment. This ensured prompt recognition of biochemical abnormalities and early diagnostic isotope scans to identify Graves’ disease in those patients who developed hyperthyroidism and liaison with the endocrinology team for all those with significant TD.