Concerns Raised Over Thyroid Disease from Interferon Treatment in Hepatitis C

Clinicians examined a patient receiving interferon alpha therapy for hepatitis C virus (HCV) infection who was experiencing thyroid dysfunction and concluded it was likely there had been a change in the nature of the antibodies being produced.

The case report was published in the Journal of Medical Case Reports and was written by Gurmit Gill of the Department of Endocrinology and Diabetes at New Cross Hospital in the UK and colleagues.

The authors say, “Clinical thyroid disease is seen in nearly 15% of patients receiving interferon alpha for hepatitis C virus infection.”

The patient described in the case report is a 29-year-old female with both type 1 diabetes and HCV. During a planned 24-week course of interferon alpha therapy, at week 17, she developed hyperthyroidism.

Laboratory tests “revealed a thyroid stimulation hormone level of 0.005 mU/L (0.350-4.94), free thyroxine of 45.6 pmol/L (9.0-19.0) and free tri-iodothyronine of 12.6 pmol/L (2.6-5.7),” the authors report. They add, “She had a mild neutropenia and alanine aminotransferase at double the reference value.”

Her thyroid was of normal size and had normal uptake.

“A diagnosis of interferon alpha-triggered autoimmune hyperthyroidism as opposed to an inflammatory thyroiditis was made,” say the authors.

She was given beta-blockers to control the symptoms and, due to personal circumstances, radioactive iodine therapy was delayed for 8 weeks.

However, “a repeat thyroid function test, 4 weeks post treatment with interferon alpha, indicated spontaneous conversion to hypothyroidism,” say the clinicians, adding, “She subsequently received levothyroxine for 4 months only and had remained euthyroid for the last 3 months without any treatment.”

The authors say this case “emphasizes the need to assess the risk of development of thyroid dysfunction prior to commencement of interferon alpha in patients with HCV infection and to monitor such patients closely clinically and biochemically.”

They also stress the need for thorough investigation into the reasons for thyroid dysfunction, adding “an unexpected pattern of thyroid dysfunction is occasionally encountered, as in our patient.”