Case report: silent thyroiditis developed during alpha-interferon therapy

Is steroid therapy needed in the treatment of destructive thyrotoxicosis induced by alpha-interferon in chronic hepatitis C?

OBJECTIVE

Treatment with interferon (IFN) of patients affected by chronic hepatitis C (CH-C) may produce alterations in thyroid function, such as hypothyroidism, Graves'-like hyperthyroidism and destructive thyrotoxicosis (DT). IFN-induced DT is characterized by suppressed serum TSH levels, normal or elevated FT4 and FT3 concentrations, with the presence or absence of thyroid peroxidase antibodies and antithyroglobulin antibodies, the absence of thyroid receptor antibodies and radioactive iodine uptake suppressed or <5%.

DESIGN

IFN-induced DT is a mild clinical disease, because thyroid-destructive processes last for a short time and involve a small portion of the gland. At present, the therapeutic approach in DT suggests IFN withdrawal and 1-2 months of methylprednisolone treatment.

METHODS

In consideration of possible untoward side effects of steroid treatment in patients with CH-C, we studied two groups of patients with CH-C who developed DT after treatments with various preparations of recombinant IFN (with or without ribavirin). Patients sequentially entered the study during a 4-year period, at the time of DT diagnosis, when IFN therapy was discontinued. The first 12 subjects (group A) were treated with 8-16 mg/day methylprednisolone for 30-40 days after IFN withdrawal; in the following 15 patients (group B), IFN withdrawal was not followed by any additional treatment. All patients underwent clinical and laboratory controls of thyroid function at 1, 2, 3 and 6 months after DT diagnosis.

RESULTS

The results showed restoration of euthyroidism in both group A and group B patients at 6 months after DT diagnosis, regardless of steroid treatment.

CONCLUSIONS

The simple withdrawal of IFN therapy in patients with CH-C, who had developed DT, appears to be effective in the treatment of the thyroid disease. This therapeutic approach should be preferred in order to avoid possible undesired side effects of steroid therapy in patients with CH-C.

Thyrotoxicosis induced by alpha-interferon therapy in chronic viral hepatitis

BACKGROUND AND OBJECTIVE

It has been well documented that treatment of chronic hepatitis B and C infection with interferon alpha (IFN-alpha) can lead to the induction of thyroid autoantibodies and hypothyroidism. Thyrotoxicosis, however, is less frequently observed and less well characterized.

PATIENTS AND METHODS

We reviewed the medical records of patients who developed thyrotoxicosis while receiving IFN-alpha for either chronic hepatitis B or C infection at Westmead Hospital between 1996 and March 2001.

RESULTS

Ten patients (four males and six females) were found to have biochemical thyrotoxicosis. The patients could be divided into two groups with different characteristics. The first group consisted of six patients who had clinical manifestations consistent with Graves' disease, with either diffuse uptake in thyroid scintigraphy and/or positive thyroid-stimulating antibodies. They all required prolonged treatment with antithyroid medications. The second group included three patients who had transient thyrotoxicosis, with progression to hypothyroidism after resolution of thyrotoxicosis.

CONCLUSION

Our study suggests that IFN therapy may provoke two different forms of thyrotoxicosis: a Graves' disease picture or a biphasic thyroiditis pattern. The two entities should be differentiated, as they have different implications for treatment.

Subacute thyroiditis during interferon-alpha therapy for chronic hepatitis C

A 34-year-old woman with chronic hepatitis C received interferon-alpha (IFN-alpha) therapy. Her thyroid function was normal and thyroid autoantibodies were negative before treatment. Four months after the beginning of the therapy she presented a clinical course of thyroiditis with a transient thyrotoxicosis. The diagnosis of subacute thyroiditis was confirmed by laboratory, ultrasonography, radioiodine scanning and fine needle aspiration findings. Thyroid autoantibodies were persisting negative. She suspended IFN-alpha therapy and she started non steroidal anti-inflammatory agents and beta-blockers. Latent hypothyroidism subsequently developed, but L-thyroxine therapy resulted in a rapid normalization of thyroid function tests.

Effect of r-interferon alpha administration on hypothalamus-pituitary-thyroid axis in chronic hepatitis

Recent studies pointed out the development of autoimmune thyroid diseases during interferon (IFN) therapy, mainly in patients with positive thyroid autoantibodies (MsAb and TgAb) before treatment. The effects of recombinant human IFN alpha (rhIFNalpha) on thyroid function and thyroid autoantibodies were studied in 12 patients with chronic active hepatitis associated with virus B or C, selected on the basis of negative results for MsAb and TgAb. No significant variation in T3, T4 and TSH levels was observed either after the first administration of rhIFN alpha (3 million IU i.m.) or after three months of therapy (3 million IU i.m. 3 times a week). TSH response to TRH was in the normal range either before or after the therapy. The absence of MsAb and TgAb was confirmed in all the patients at the end of the treatment. These results indicate that no patient developed thyroid disorder during IFN therapy. Nevertheless, since positive MsAb and TgAb have been considered as a risk factor for thyroid diseases, in patients selected for IFN therapy they should be carefully assessed for autoantibodies before undergoing IFN treatment.

Multiple changes in thyroid function in patients with chronic active HCV hepatitis treated with recombinant interferon-alpha

OBJECTIVE

Recombinant human interferon-alpha (r-IFN-alpha) is often successfully used in the treatment of patients with chronic viral hepatitis B and C. Thyroid dysfunction has been reported to occur with variable frequency during r-IFN-alpha therapy especially in patients with preexisting thyroid autoimmunity. We have prospectively evaluated the effect of r-IFN-alpha on various aspects of thyroid function in patients with HCV chronic hepatitis.

DESIGN

Thirty-two patients with HCV chronic active hepatitis were studied prospectively before and during r-IFN-alpha therapy. Serum TSH, FT4, FT3, and thyroid receptor (TSR) and thyroid peroxidase (TPO) antibodies, and the iodide-perchlorate discharge test (I-C10(4)) to detect subtle defects in the thyroid organification of iodide were carried out during the study. Thyroid radioactive iodine uptakes (RAIU) were obtained in patients who developed thyrotoxicosis.

RESULTS

All patients were clinically and biochemically euthyroid prior to r-IFN-alpha therapy with negative I-C10(4) discharge tests. Four patients became thyrotoxic, 3 secondary to destructive or inflammatory thyroiditis with a low thyroid RAIU, and 1 patient developed hypothyroidism. The I-C10(4) discharge test became positive in 7 of the 32 patients studied prospectively; 5 of these patients did not develop other evidence of thyroid dysfunction and did not have positive TPO antibodies. In these 5 patients the test became negative after r-IFN-alpha was discontinued. Appropriate therapy of the patients with thyrotoxicosis (methylprednisolone for 3 patients with destructive thyroiditis and methimazole for 1 patient with hyperthyroidism) or with hypothyroidism (L-thyroxine) was successful.

CONCLUSIONS

Thyroid dysfunction, especially destructive or silent thyroiditis resulting in thyrotoxicosis, is not infrequently observed in patients receiving r-IFN-alpha therapy for chronic active hepatitis. Although underlying autoimmune thyroid disease appears to predispose patients to develop thyroid dysfunction, other patients become thyrotoxic or hypothyroid in the absence of baseline positive TPO-Ab. Subtle defects in the thyroidal organification of iodine as determined by the I-C10(4) discharge test, in the absence of autoimmune thyroid disease, was observed in 5 patients who remained euthyroid, suggesting that r-IFN-alpha directly reduces the intrathyroidal organification of iodine.

Clinical use of sensitive assays for thyroid-stimulating hormone

OBJECTIVE

To review the optimal use of sensitive assays for thyroid-stimulating hormone (TSH) by clinicians.

METHODS

The available literature pertinent to the clinical application of sensitive TSH testing was identified through a systematic MEDLINE search and reviewed. Selection of materials for inclusion was based on clinical validity of the data and relevance to the study question.

SYNOPSIS

Sensitive TSH assays have contributed greatly to our basic knowledge of thyroid physiology and are a powerful clinical tool in the diagnosis and treatment of thyroid disease. The clinical applicability of these assays, as is our understanding of their appropriate use, is rapidly expanding. Based upon the best evidence and current understanding of thyroid physiology, strategies are presented for appropriate use of sensitive TSH assays in healthy outpatients, in patients who are likely to have a disturbed hypothalmic-pituitary-thyroid axis, and in patients on levothyroxane therapy.

CONCLUSIONS

Although many clinical questions regarding the use of sensitive TSH assays remain to be studied, it has emerged as a powerful tool for the diagnosis and management of thyroid disease. Optimal use of sensitive TSH assays requires an understanding of TSH physiology and measurement, coupled with appropriate application and interpretation in specific clinical settings.