Hepatitis C- Rare case of pegylated IFN-α induced destructive thyroiditis followed by Graves' disease
- File Under side effects, thyroid
Also See- Hepatitis C- Thyroid dysfunction
Interferon-Alpha-Induced Destructive Thyroiditis Followed by Graves' Disease in a Patient with Chronic Hepatitis C: A Case Report
Bu Kyung Kim, Young Sik Choi, Yo Han Park, and Sang Uk Lee
Corresponding author.
Address for Correspondence: Young Sik Choi, MD. Department of Internal Medicine, Kosin University College of Medicine, 262 Gamcheon-ro, Seo-gu, Busan 602-702, Korea. Tel: +82.51-990-6102, Fax: +82.51-248-5686, Email: yschoi@kosinmed.or.kr
Received July 4, 2011; Accepted September 25, 2011.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: Interferons, Destructive Thyroiditis, Graves Disease
INTRODUCTION
A 31-yr-old woman with hepatitis C-associated chronic active hepatitis proven on liver biopsy received pegIFN-α (Schering-Plough, Korea) 2b 100 µg weekly and ribavirin 800 mg daily from June 2009 to May 2010. Prior to pegIFN-α therapy, laboratory testing revealed normal concentrations of total T3 at 2.25 nM/L (normal range: 1.1 to 2.9 nM/L), TSH at 1.011 mU/L (normal range: 0.35 to 5.50 mU/L), and free T4 at 15.18 pM/L (normal: 9 to 26 pM/L), in addition to negative titers of antimicrosomal antibody (MSAb) at 18 U/mL (negative < 60 U/mL) and antithyroglobulin antibody (TGAb) at 26.7 U/mL (negative < 60 U/mL). Within two months of pegIFN-α therapy initiation she experienced fever, chills, headaches and dizziness. Seven months into therapy (January 2010), the patient developed mild tremors and palpitation however she had no fever or pain. There was no tenderness and palpable nodule at physical examination. She has no personal and family history of thyroid dysfunction and no specific medication history. She also had not received any test that could interfere with the thyroid scan uptake.
Results of repeated laboratory tests indicated elevated total T3 at 4.26 nM/L, suppressed TSH at 0.009 mU/L, normal total T4 at 148.005 nM/L (normal: 64 to 154 nM/L), and negative titers of MSAb at 27.1 U/mL and TGAb at 31.1 U/mL. Thyrotropin-binding inhibitory immunoglobulin (TBII) was also negative at 2.6 U/L (normal range: 0 to 10 U/L). Tc-99m scintigraphy showed nonvisualization of both thyroid lobes (Fig. 1A). Based on these findings, we diagnosed the patient with interferon-induced destructive thyroiditis and prescribed propranolol 20 mg/d for one month.

Tc-99m scintigraphy showing non-visualization of the thyroid gland (A) and increased uptake throughout (B).
Two months later (March 2010), a follow-up thyroid function test demonstrated further decline in total T3 at 3.353 nM/L, TSH at 0.013 mU/L and total T4 at 128.7 nM/L. She continued pegIFN-α therapy for an additional four months, for a total treatment duration of 12 months. Two months after the end of therapy (July 2010), she complained of hand tremors, fatigability, and 3 kg of weight loss. Laboratory tests revealed a total T3 of 12.288 nM/L, TSH of 0.004 mU/L, free T4 of 79.92 pM/L, and a TBII titer of 13.0 U/L. Tc-99m scintigraphy showed diffusely increased uptake throughout the thyroid (Fig. 1B). In thyroid ultrasonography both thyroid glands were diffusely enlarged with increased vascularities and had heterogeneous echogenicities (Fig. 2). The diagnosis of Graves' disease was made, and the patient started treatment with methimazole and propranolol.
After nine months of antithyroid drug therapy (April 2011), her thyroid function tests showed normalized total T3 at 2.095 nM/L, TSH at 0.009 mU/L, free T4 at 21.36 pM/L, MSAb at 40.9 U/mL and TBII at 3.4 U/L. However, her TGAb titer was weakly positive at 63.9 U/mL.
DISCUSSION

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