Interferon therapy hypothyroidism with

Interferon-a causes hypothyroidism in up to 39% of patients being treated for hepatitis C infection. Patients may develop a transient thyroiditis with hyperthyroidism prior to becoming hypothyroid. The hypothyroidism may be transient as well. Asians and patients with preexisting anti-TPOAbs are more likely to develop interferon-induced hypothyroidism. The mechanism of interferon-induced hypothyroidism is not known. If LT4 replacement is initiated, it should be stopped after 6 months to re-evaluate the need for replacement therapy. 

Cytokines Interferon- and interleukin-2 - Therapy with interferon- has been associated with the development of antithyroid microsomal antibodies in 20% of patients and some have transient hypothyroidism, hyperthyroidism, or both. Patients who have antithyroid antibodies before treatment are at higher risk of thyroid dysfunction during treatment. Interleukin-2 has been associated with transient painless thyroiditis in 20% of patients. 

Carella C, Mazziotti G, Morisco F, Rotondi M, Cioffi M, Tuccillo C, Sorvillo F, Caporaso N, Amato G. The addition of ribavirin to interferon-alpha therapy in patients with hepatitis C virus-related chronic hepatitis does not modify the thyroid autoantibody pattern but increases the risk of developing hypothyroidism. Eur J Endocrinol 2002 146(6) 743-9. 

Endocrine In a retrospective study of 260 patients who received interferon-I-ribavirin for hepatitis C infection 10% developed a suppressed serum TSH (0.8% Graves disease, 9.6% transient thyroiditis) and 12% developed a raised serum TSH 1.5% developed permanently hypothyroidism and requiring levothyroxine [49 ]. Women had a relative risk of thyroid dysfunction of 1.96 (95% Cl = 1.8, 3.0). A serum TSH of 1.75 mU/1 or more and a positive thyroid peroxidase antibody titer before therapy were associated with relative risks of 6.0 (95% Cl=3.0, 13) and 4.4 (95% Cl = 2.6, 6.5) respectively. The combination of baseline TSH and thyroid peroxidase antibody data predicted progression to thyroid dysfunction with a sensitivity of 95%. 

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