The risk factor for development of thyroid disease during interferon-alpha therapy for chronic hepatitis C

To determine the risk factors for the development of thyroid diseases during interferon-alpha therapy, we analyzed the patients with chronic hepatitis C who were treated with interferon-alpha.

One hundred nine patients with chronic hepatitis C (77 men and 32 women, ages 20-72 yr) were treated with interferon-alpha (alpha, 48; alpha 2a, 38; alpha 2b, 23) for 14-40 wk. Thyroid function tests and seven autoantibodies were assessed at the beginning and end of interferon-alpha therapy, and every other month. A logistic multiple regression model was used in the statistical analysis of risk factors for development of thyroid diseases.

Among the 106 patients with normal pretreatment thyroid function tests, nine patients (three men and six women, ages 33-62 yr) developed thyroid diseases. However, among three patients with abnormal thyroid function tests, exacerbation of thyroid disease was not observed during interferon-alpha therapy. Logistic multiple regression model revealed that positivity for microsome antibody was a significant risk factor for the development of thyroid disease (p < 0.0001, chi 2 = 20.18). Actually, compared to patients without microsome antibody at the beginning of therapy, the incidence of thyroid diseases in the patients with pretreatment microsome antibody was very high: 3.3% (3/99) versus 60% (6/10), respectively. Six patients developed hyperthyroidism and three patients developed hypothyroidism. The patients with hyperthyroidism had atypical clinical features.

Our study revealed that positivity for microsome antibody at the beginning of interferon-alpha therapy is a risk factor for thyroid dysfunction.