OBJECTIVETo investigate the relation of thyroid function with hashimoto thyroiditis (HT, an autoimmune disease of unknown etiology also known as chronic lymphocytic thyroiditis) in patients with chronic hepatitis C (CHC) receiving treatment with pegylated-interferon-alpha (Peg-IFNa) based on the observation that HT is common among individuals undergoing IFN-based therapy.

METHODSOne-hundred-and-seven patients with chronic hepatitis C were enrolled for study between January 2008 and December 2010. Thyroid function was assessed by electrochemiluminescence assays to detect serum levels of anti-thyroid peroxidase (A-TPO) antibodies, thyroid stimulating hormone (TSH), and free thyroxine (FT4) prior to initiation of the IFN-based therapy. The treatment strategies (drugs, doses, schedules) were designed according to HT status (CHC with HT, or CHC without HT). Patients were monitored during the 24 weeks of treatment (including measuring serum alanine aminotransferase (ALT), TSH, and FT4 every two to four weeks, and HCV RNA every four weeks) so that the IFNa dose could be adjusted and thyroid medications (levothyroxine sodium or methimazole) added as necessary. The response rate at end of treatment (week 24) was assessed.

RESULTSTwenty-one of the CHC patients were diagnosed with HT, and the incidence of thyroid dysfunction among the CHC patients with HT was 71.4% (15/21); among the CHC patients with no HT, the incidence of thyroid dysfunction was significantly lower (30.2% (26/86), X2 = 12.1995, P less than 0.01). In the CHC patients with HT, 90.5% (19/21) had serum levels of A-TPO antibodies that were more than or equal to 2-times higher than the normal value at the end of treatment. Of the 15 CHC patients with HT and thyroid dysfunction, 73.3% (11/15) continued to show thyroid dysfunction at the end of treatment. Hypothyroidism was the most common form of thyroid dysfunction observed (4/11), and all of those patients responded to levothyroxine sodium treatment. The virological response rates of the two groups (CHC with HT and CHC without HT) were not significantly different at any time point examined (treatment week 4, 12, and 24, P more than 0.05).

CONCLUSIONThe incidence of thyroid dysfunction is significantly higher among CHC patients with HT than among CHC patients without HT. If suspected, these patients should be carefully monitored because the clinical symptoms of thyroid dysfunction are not obvious and the drug therapy should be carefully adjusted to minimize the thyroid dysfunction while maximizing the antiviral effect.