Table 6 Major summary points from the study

1. The majority of patients with HCV undergoing combination IFN-α and RBV therapy have normal thyroid function.

2. The commonest cause of thyroid dysfunction is hypothyroidism, a ratio of 4:1 compared with hyperthyroidism.

3. The average time from the start of anti-viral treatment to hypothyroidism is ~4–5 months, suggesting that this is the critical time to carry out thyroid testing.

4. Predisposing risk factors include female gender, family history of thyroid disease and existing thyroid auto-antibodies, especially anti-TPO antibodies. In this situation, initial TSH should be performed to exclude pre-existing hypothyroidism.

5. Hyperthyroidism is less common and each should be managed on its own merits in a specialised Endocrine service.