Autoimmune thyroid dysfunction induced by interferon-alpha treatment for chronic hepatitis C: screening and monitoring recommendations

The interplay between thyroid and liver: implications for clinical practice

A complex relationship exists between thyroid and liver in health and disease. Liver plays an essential physiological role in thyroid hormone activation and inactivation, transport, and metabolism. Conversely, thyroid hormones affect activities of hepatocytes and hepatic metabolism. Serum liver enzyme abnormalities observed in hypothyroidism may be related to impaired lipid metabolism, hepatic steatosis or hypothyroidism-induced myopathy. Severe hypothyroidism may have biochemical and clinical features, such as hyperammonemia and ascites, mimicking those of liver failure. Liver function tests are frequently abnormal also in hyperthyroidism, due to oxidative stress, cholestasis, or enhanced osteoblastic activity. Antithyroid drug-associated hepatotoxicity is a rare event, likely related mainly to an idiosyncratic mechanism, ranging from a mild hepatocellular damage to liver failure. Propylthiouracil-induced liver damage is usually more severe than that caused by methimazole. On the other hand, thyroid abnormalities can be found in liver diseases, such as chronic hepatitis C, liver cirrhosis, hepatocellular carcinoma, and cholangiocarcinoma. In particular, autoimmune thyroid diseases are frequently found in patients with hepatitis C virus infection. These patients, especially if thyroid autoimmunity preexists, are at risk of hypothyroidism or, less frequently, thyrotoxicosis, during and after treatment with interpheron-alpha alone or in combination with ribavirin, commonly used before the introduction of new antiviral drugs. The present review summarizes both liver abnormalities related to thyroid disorders and their treatment, and thyroid abnormalities related to liver diseases and their treatment.

Thyroid dysfunctions secondary to cancer immunotherapy

BACKGROUND

Immunotherapy is a firmly established pillar in the treatment of cancer, alongside the traditional approaches of surgery, radiotherapy, and chemotherapy. Like every treatment, also cancer immunotherapy causes a diverse spectrum of side effects, collectively referred to as immune-related adverse events.

OBJECTIVE

This review will examine the main forms of immunotherapy, the proposed mechanism(s) of action, and the incidence of thyroid dysfunctions.

METHODS

A comprehensive MEDLINE search was performed for articles published up to March 30, 2017.

RESULTS

Following the pioneering efforts with administration of cytokines such as IL-2 and IFN-g, which caused a broad spectrum of thyroid dysfunctions (ranging in incidence from 1 to 50%), current cancer immunotherapy strategies comprise immune checkpoint inhibitors, oncolytic viruses, adoptive T-cell transfer, and cancer vaccines. Oncolytic viruses, adoptive T-cell transfer, and cancer vaccines cause thyroid dysfunctions only rarely. In contrast, immune checkpoint blockers (such as anti-CTLA-4, anti-PD-1, anti-PD-L1) are associated with a high risk of thyroid autoimmunity. This risk is highest for anti-PD-1 and increases further when a combination of checkpoint inhibitors is used.

CONCLUSIONS

Cancer patients treated with monoclonal antibodies that block immune checkpoint inhibitors are at risk of developing thyroid dysfunctions. Their thyroid status should be assessed at baseline and periodically after initiation of the immunotherapy.

Thyroid Dysfunction in Non-Interferon Treated Hepatitis C Patients Residing in Hepatitis Endemic Area

Background

Association of thyroid dysfunction (TD) with interferon treatment of HCV is well known to clinicians. However, a few studies have highlighted the role of hepatitis C virus per se in the development of TD. The aim of this study was to know the prevalence of TD in non-interferon treated HCV infected patients referred for thyroid function testing.

Patients and Methods

Among 557 ELISA-positive HCV patients 446 (341 females, 105 males) were selected for this study. Serums FT₄, FT₃, and TSH were determined by radioimmunoassay method.

Results

TD was detected in 15.2% of patients: 9.0% hypothyroidism and 6.3% hyperthyroidism. In increasing order subclinical hypothyroidism, overt hypothyroidism, overt hyperthyroidism, and subclinical hyperthyroidism were found in 4.7%, 4.3%, 3.6%, and 2.7% patients, respectively. Overall TD was more common in female than in male HCV patients but the difference was not significant (16.1% versus 12.4%; p = 0.648). Hyperthyroidism and subclinical hypothyroidism were slightly more common in female and overall hypothyroidism and overt hypothyroidism in male patients but the difference was not statistically significant (p > 0.05). The incidence of TD was relatively high in patients above 36 years (median age) but the difference was not statistically significant either collectively or in gender base groups (p > 0.05).

Conclusion

Prior to interferon treatment, HCV infection itself causes biochemical thyroid dysfunction in 15.2% of local HCV patients.

The clinical use of thyroid function tests

Laboratory tests are essential for accurate diagnosis and cost-effective management of thyroid disorders. When the clinical suspicion is strong, hormonal levels just confirms the diagnosis. However, in most patients, symptoms are subtle and unspecific, so that only biochemical tests can detect the disorder. The objective of this article is to do a critical analysis of the appropriate use of the most important thyroid function tests, including serum concentrations of thyrotropin (TSH), thyroid hormones and antithyroid antibodies. Through a survey in the MedLine database, we discuss the major pitfalls and interferences related to daily use of these tests and recommendations are presented to optimize the use of these diagnostic tools in clinical practice.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

Autoimmune enteropathy: a review and update of clinical management

Autoimmune enteropathy (AIE) is a rare condition characterized by intractable diarrhea, histologic changes on small intestinal biopsy, and failed response to dietary manipulation that also may present with extraintestinal manifestations. In many patients, immunosuppressive therapies are necessary. Although AIE is more common in infants, adult involvement has also been documented. Much of what is known about AIE has been gathered from case reports and small case series; therefore, more research in this evolving field is needed. IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked syndrome) and APECED (autoimmune phenomena, polyendocrinopathy, candidiasis, and ectodermal dystrophy) are systemic forms of AIE.

Diagnostic value of antithyroid peroxidase antibody for incidental autoimmune thyroiditis based on histopathologic results

Detection of antithyroid peroxidase antibody (TPOAb) is widely used in the diagnosis of autoimmune thyroiditis (AIT), but no research has evaluated the diagnostic accuracy of TPOAb detection using histopathologic reference standards. To fill this research gap, this study assessed the diagnostic accuracy of detection of TPOAb and that of other serological markers in asymptomatic patients who had been diagnosed with AIT by histopathologic analysis after thyroid surgery. After review of patient records, 598 patients who had undergone thyroid nodule surgery were enrolled for examination for thyroid parenchyma by a pathologist and classification into no co-existing lymphocytic thyroiditis, Hashimoto thyroiditis, or non-Hashimoto type of lymphocytic thyroiditis (NHLT). The correlation between patient serological data and thyroid parenchyma pathology was analyzed. Statistically significant differences (P < 0.05) were found between co-existing lymphocytic thyroiditis and no co-existing lymphocytic thyroiditis groups regarding thyroid-stimulating hormone (TSH) and TPOAb levels. And, TPOAb titer was significantly associated with the degree of inflammation. An abnormal TPOAb titer was found in 86 of the 598 patients (14.4 %) and the specificity of TPOAb detection for AIT diagnosis was found to be 96.9 %. The prevalence of Hashimoto thyroiditis and NHLT in the 560 papillary thyroid cancer (PTC) patients was found to be 7.9 and 17.9 %, respectively. The results indicate that TPOAb titer is associated with the degree of thyroid inflammation and that detection of TPOAb is a very specific means of diagnosing AIT. The results also indicate that the incidence of AIT and PTC coexistence is relatively high.

Autoimmune enteropathy: a review and update of clinical management

Autoimmune enteropathy (AIE) is a rare condition characterized by intractable diarrhea, histologic changes on small intestinal biopsy, and failed response to dietary manipulation that also may present with extraintestinal manifestations. In many patients, immunosuppressive therapies are necessary. Although AIE is more common in infants, adult involvement has also been documented. Much of what is known about AIE has been gathered from case reports and small case series; therefore, more research in this evolving field is needed. IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked syndrome) and APECED (autoimmune phenomena, polyendocrinopathy, candidiasis, and ectodermal dystrophy) are systemic forms of AIE.

Thyroid dysfunction from antineoplastic agents

Unlike cytotoxic agents that indiscriminately affect rapidly dividing cells, newer antineoplastic agents such as targeted therapies and immunotherapies are associated with thyroid dysfunction. These include tyrosine kinase inhibitors, bexarotene, radioiodine-based cancer therapies, denileukin diftitox, alemtuzumab, interferon-α, interleukin-2, ipilimumab, tremelimumab, thalidomide, and lenalidomide. Primary hypothyroidism is the most common side effect, although thyrotoxicosis and effects on thyroid-stimulating hormone secretion and thyroid hormone metabolism have also been described. Most agents cause thyroid dysfunction in 20%-50% of patients, although some have even higher rates. Despite this, physicians may overlook drug-induced thyroid dysfunction because of the complexity of the clinical picture in the cancer patient. Symptoms of hypothyroidism, such as fatigue, weakness, depression, memory loss, cold intolerance, and cardiovascular effects, may be incorrectly attributed to the primary disease or to the antineoplastic agent. Underdiagnosis of thyroid dysfunction can have important consequences for cancer patient management. At a minimum, the symptoms will adversely affect the patient's quality of life. Alternatively, such symptoms can lead to dose reductions of potentially life-saving therapies. Hypothyroidism can also alter the kinetics and clearance of medications, which may lead to undesirable side effects. Thyrotoxicosis can be mistaken for sepsis or a nonendocrinologic drug side effect. In some patients, thyroid disease may indicate a higher likelihood of tumor response to the agent. Both hypothyroidism and thyrotoxicosis are easily diagnosed with inexpensive and specific tests. In many patients, particularly those with hypothyroidism, the treatment is straightforward. We therefore recommend routine testing for thyroid abnormalities in patients receiving these antineoplastic agents.

Environmental triggers of thyroiditis: hepatitis C and interferon-α

Autoimmune thyroid diseases (AITD) are postulated to develop as a result of a complex interplay between several genetic and environmental influences. The pathogenesis of AITD is still not clearly defined. However, among the implicated triggers (e.g. iodine, infections, medications), more recent data confirmed strong associations of AITD with the hepatitis C virus (HCV) infection and interferon-α (IFNα) therapy. Moreover, it is likely that HCV and IFN act in synergism to trigger AITD in patients. Indeed, approximately 40% of HCV patients develop either clinical or subclinical disease while receiving IFNα. Interferon induced thyroiditis (IIT) can manifest as non-autoimmune thyroiditis (presenting as destructive thyroiditis, or non-autoimmune hypothyroidism), or autoimmune thyroiditis [presenting with clinical features of Graves' disease (GD) or Hashimoto's thyroiditis (HT)]. Although not yet clearly understood, it is thought that IFNα can induce thyroiditis via both immune stimulatory and direct toxic effects on the thyroid. In view of the high frequency of IIT, routine screening and surveillance of HCV patients receiving IFNα is recommended to avoid the complications, such as cardiac arrhythmias, associated with thyrotoxicosis. In summary, IIT is a common clinical problem that can be readily diagnosed with routine thyroid function screening of HCV patients receiving IFN. The treatment of IIT consists of the standard therapy for differing clinical manifestations of IIT such as GD, HT, or destructive thyroiditis. However, anti-thyroid medications are not recommended in this setting since they can potentially be hepatotoxic.

Thyroid dysfunction in patients with chronic hepatitis C: virus- or therapy-related?

BACKGROUND AND AIMS

Thyroid dysfunction (TD) represents an extrahepatic manifestation of chronic hepatitis C (CHC). Moreover, the currently approved treatment of CHC is often associated with TD. However, it remains debatable if TD is mainly virus- or treatment-related. The aim of this study was to assess the incidence and features of TD, and to identify its predictors in treated and untreated CHC patients.

METHODS

Ninety-four patients with CHC and normal thyroid function were evaluated long-term for TD: 33 were untreated (control group) and 61 were treated with pegylated interferon alpha (PEG-IFN-alpha) plus ribavirin (treatment group). Mean follow up was 80.1 and 39.4 months, respectively.

RESULTS

All patients in the control group remained euthyroid, while 13 treated patients (21.3%) developed TD (P < 0.001). Eleven of these were diagnosed with hypothyroidism and two with hyperthyroidism, which then converted to hypothyroidism. In the majority of cases (9/13, 69.2%) TD did not reverse after treatment discontinuation and required hormone replacement therapy. Pretreatment virological parameters did not predict TD, according to multiple logistic regression analysis. TD was not associated with total dose of PEG-IFN-alpha or ribavirin, viral kinetics or with virological outcome, but it was linked to development of other therapy-related autoimmune disorders (odds ratio, 8.29).

CONCLUSION

Antiviral therapy of CHC possibly induces de novo or exacerbates pre-existing silent TD. TD does not seem to correlate with any pretreatment virological parameter; it is probably not related to dose or treatment duration, nor linked to viral kinetics or virological outcome. The role of chronic hepatitis C per se in TD remains to be determined.

Prevalence of active hepatitis C virus infection in patients with systemic lupus erythematosus

OBJECTIVE

Hepatitis C virus (HCV) infection is associated with various autoimmune disorders and can mimic systemic lupus erythematosus (SLE) clinically and serologically. There are few reports of prevalence of HCV infection in patients with SLE. The aim of this study was to determine the prevalence of HCV viremia by polymerase chain reaction (PCR) in patients with SLE.

METHODS

We tested sera from 40 consecutive patients with SLE collected from 1993 to 2000. All of the patients had HCV viral load measured by PCR. The results were compared with the prevalence of HCV viremia in a control group of blood donors in our geographic area as well as in United States general population.

RESULTS

HCV was detected in 4 of 40 patients (10%). The prevalence of HCV in our area blood donors is 130 cases per 100,000 persons (0.13%; P<0.0001). The prevalence of HCV infection in the United States general population, screened by PCR, is 1330 cases per 100,000 people (1.33%; P=0.002). The prevalence of HCV infection was significantly higher in our SLE patients than in our area blood donors. The frequency of HCV infection was also higher than that of the United States general population.

CONCLUSION

Our observations support those of other investigators who have reported an increased prevalence of HCV infection in SLE patients. Further detailed investigation of this association may help in understanding the pathogenesis of SLE. HCV infection should be tested when the diagnosis of SLE is considered.

Clinical uses of recombinant human thyrotropin

Recombinant human thyroid-stimulating hormone (rhTSH), used to enhance diagnostic radioiodine whole body scanning and thyroglobulin testing, has dramatically altered the management of patients with thyroid cancer. Withdrawal from thyroid hormone suppression therapy and subsequent hypothyroidism is no longer the only safe and effective method for thyroid cancer surveillance. Currently, rhTSH is only approved for the monitoring of low-risk patients with well-differentiated thyroid cancer and radioactive iodine administration, in selected cases. Additional applications of rhTSH include enhancing the sensitivity of positron emission tomography in thyroid cancer, the management of multinodular goiter, and dynamic testing of thyroid reserve. The diagnostic and therapeutic role of rhTSH in these areas is discussed in this review.

Impact of adherence on the outcome of antiviral therapy for chronic hepatitis C

Nearly 4 million people in the United States have evidence of hepatitis C infection (HCV), representing a significant cause of cirrhosis and liver cancer as well a major burden to our healthcare systems and society. Antiviral therapy can successfully eradicate HCV over the long term, potentially reducing the risk of progression and improving patients' quality of life. The currently preferred HCV treatment is a combination of pegylated interferon alfa and ribavirin, which can achieve an overall sustained viral eradication rate of 55%. The duration of this treatment is typically determined by HCV genotype and the patient's early virologic response to the antiviral regimen. Evidence has accumulated over the past few years to indicate that close adherence to the optimal antiviral regimen can enhance sustained virologic response. But optimal treatment outcomes require diligence and careful management of side effects related to combination therapy. Although reducing the dose of pegylated interferon alfa, ribavirin, or both can effectively treat side effects, suboptimal doses of this regimen, especially ribavirin, may negatively affect virologic response. An alternative strategy is to use growth factors to treat cytopenias. This strategy can obviate dose reductions while potentially improving patients' quality of life. Patient support seems especially important early after the initiation of antiviral therapy. Encouraging study findings involving the growth factors, epoetin alfa and darbepoetin alfa, suggest improved anemia and quality of life while maintaining the optimal ribavirin dose. Future work should be aimed at providing stronger evidence for the use of these "supportive products" during anti-HCV therapy. As we strive to develop better treatment options for our HCV patients, the importance of adhering to the treatment regimen continues to play a central role. Effective side effect management is crucial for the success of this treatment because adherence is negatively affected by side effects related to the antiviral regimen. By identifying and addressing the important side effects of combination therapy for HCV, adherence to treatment can be improved and optimal outcomes can be achieved.