TSH-receptor antibody measurement for differentiation of hyperthyroidism into Graves' disease and multinodular toxic goitre: a comparison of two competitive binding assays

Biological variation in thyroid function tests in older adults and clinical implications

OBJECTIVE

Interpreting thyroid function tests can be challenging due to inherent variation, and the need for tests rises with age. While age-related changes in thyrotropin (TSH) levels are known, the biological variation in older adults remains unclear.

DESIGN

We recruited nineteen 65-99-year-old (older adults) without thyroid disease for monthly blood sampling for 1 year.

PATIENTS AND MEASUREMENTS

Serum was stored at -20C°, and TSH, total thyroxine (TT4) and total triiodothyronine (TT3) were analysed in random order in a single batch for each participant. Results were compared to test results from 15 euthyroid men aged 24-53 years (younger adults) collected previously using a similar methodology.

RESULTS

Interindividual coefficients of variation in older/younger adults were 46.7%/44.0% for TSH, 12.7%/19.5% for TT4 and 14.6%/22.4% for TT3. Intraindividual coefficients of variation (CVI ) were 19.0%/25.4% for TSH, 5.5%/10.8% for TT4 and 6.9%/13.2% for TT3. The index of individuality was below 0.6 for all hormones in all age groups. The number of samples required to determine the homoeostatic set-point at 10% precision in older adults was 14-21 for TSH and 2 for TT4 and TT3. TT4 in older adults was the only parameter in any group with comparable CVI between individuals (p = .22).

CONCLUSIONS

CVI for TT4 and TT3 was halved in older compared to younger adults with two tests of TT4 needed to describe the individual set-point. Similar CVI between older adults caused TT4 to provide a reliable estimate of thyroid function, and the added value of measuring thyroxine could improve clinical practice.

Thyrotropin Receptor Antibodies in Early Pregnancy

CONTEXT

Thyrotropin (TSH) receptor antibodies (TRAb) are important when distinguishing between Graves' and gestational hyperthyroidism, but sparse evidence exists on the recommended cutoff during pregnancy.

OBJECTIVE

This work aimed to establish a method- and pregnancy-specific cutoff for TRAb, to describe the frequency of TRAb positivity in early pregnancy, and to follow up the women in the years after pregnancy.

METHODS

This cohort study used the North Denmark Region Pregnancy Cohort and Danish nationwide registers of women in the North Denmark Region who had a blood sample drawn in early pregnancy, 2011 to 2015, that was stored in a biobank for assessment of thyroid function and thyroid autoantibodies. A cutoff value for TRAb was established in a reference cohort (n = 524) and used to identify TRAb-positive and TRAb-negative hyperthyroidism in early pregnancy for evaluation of frequency and follow-up.

RESULTS

The method- and cohort-specific cutoff for TRAb in early pregnancy was 0.98 IU/L (95% CI, 0.96-0.99 IU/L). Among women with low TSH in early pregnancy and no known thyroid disease (n = 414), 21 women (5.1%) were TRAb positive and 393 (94.9%) were TRAb negative. Follow-up in the years following the pregnancy (median 8.1 years) revealed that 52.4% of women with TRAb-positive hyperthyroidism and 8.4% of the women with TRAb-negative hyperthyroidism were diagnosed with hyperthyroidism.

CONCLUSION

This is the first study to measure TRAb in a large group of women in early pregnancy and to establish a pregnancy-specific cutoff. Results reveal that TRAb-negative hyperthyroidism is predominant in early pregnancy and rarely associated with later development of hyperthyroidism.

The prevalence and significance of nonuniform thyroid radio-isotope uptake in patients with Graves' disease

OBJECTIVE

To evaluate the prevalence and clinical significance of nonuniform technetium (^99m Tc) uptake among patients with Graves' disease (GD).

DESIGN, PATIENTS AND MEASUREMENTS

Patients with GD, referred between July 2005 and March 2018, had Tc⁹⁹ - uptake scans and TSH-receptor antibody (TRAb) measured before antithyroid drug (ATD) therapy. Risk of relapse after ATD cessation was monitored until June 2021 and compared between GD patients based on uptake patterns.

RESULTS

Of the 276 GD patients (mean age, 49.8 years; 84% female), 25 (9.0%) had nonuniform Tc⁹⁹ uptake. At diagnosis, individuals with nonuniform uptake were older (mean age of 61.8 vs. 48.5 years, p < .001), had lower mean thyroid hormone levels (free thyroxine: 36.3 vs. 45.4  pmol/L, p = .04 and free triiodothyronine: 10.0 vs. 17.8 pmol/L, p < .001) and median TRAb levels (4.2 vs. 6.6 U/L, p = .04) compared with those with a uniform uptake. Older age was a significant predictor for the presence of nonuniform uptake in GD patients; odds ratio (95% confidence intervals) of 1.07 (1.03 - 1.10). The risk of relapse was similar in both groups after a median (IQR) follow-up of 41 (13-74) months after ATD cessation (56.0% vs. 46.3%, respectively); hazard ratio (95% confidence intervals) of 1.74 (0.96-3.15).

CONCLUSIONS

Nonuniform radio-isotope uptake is seen in 1 in 11 patients with GD which could be misdiagnosed as toxic multinodular goitre if TRAb levels are not measured. Treatment of GD patients with nonuniform radio-isotope uptake with ATD therapy as first-line appears to be equally effective as compared with those with uniform uptake. TRAb testing should be the main diagnostic test for patients with suspected GD with radio-labelled uptake scans being reserved for those who are TRAb negative.

Utility of TSH Receptor Antibodies in the Differential Diagnosis of Hyperthyroidism in Clinical Practice

Graves' disease (GD) is the most common cause of hyperthyroidism in iodine-sufficient areas. It is important to distinguish GD from other causes of hyperthyroidism for optimal management. Thyroid stimulating hormone receptor antibody (TRAb) test is a commonly used test for this purpose. However, the sensitivity for this test in routine clinical practice may be affected by various factors leading to fallacies in diagnosis.

Materials and Methods

A retrospective study was performed to assess the utility of an automated electrochemiluminescence TRAb immunoassay (Roche) in differentiating GD from non-Graves' disease (NGD) in routine clinical practice.

Results

In 227 subjects, 146 had GD and 81 had NGD. Total T3, Total T4, Free T4, and TRAb were significantly higher in people with GD in comparison to NGD. The area under the receiver operating characteristics (ROC) curve for the assay was 0.96 (95% CI: 0.926 to 0.984, P < 0.0001). The optimal threshold for the test derived from the ROC was 3.37 IU/L, which is more than the cut-off of 1.75 IU/L suggested by the manufacturer. The sensitivity/specificity of TRAb in the diagnosis of GD at presentation was 98.4%/62.9% at 1.75 IU/L and 91.2%/90.12% at 3.37 IU/L, respectively.

Conclusion

The TRAb test is a sensitive test to differentiate between subjects with GD and NGD presenting with hyperthyroidism. However, the cutoff (1.75 IU/L) as per the kit manufacturer may lead to a lower specificity for diagnosis. A modified cut-off of 3.37 IU/L should be considered for optimizing the diagnostic efficacy of the test.

Recombinant human thyrotropin (rhTSH)-aided radioiodine treatment for non-toxic multinodular goitre

BACKGROUND

Multinodular goitre is common in women. Treatments for non-toxic multinodular goitre include surgery, levothyroxine suppressive therapy, and radioiodine. Radioiodine therapy is the only non-surgical alternative for non-toxic multinodular goitre. However, a high amount of radioiodine is needed to enable the thyroid nodules to adequately take up the radioiodine, because the multinodular goitre takes up a low amount of iodine. Recombinant human thyrotropin (rhTSH) has been used to increase radioiodine uptake and reduce thyroid volume of the multinodular goitre. Whether the improved reduction of the goitre resulting from rhTSH-stimulated radioiodine therapy is beneficial to the person remains controversial.

OBJECTIVES

To assess the effects of recombinant human thyrotropin-aided radioiodine treatment for non-toxic multinodular goitre.

SEARCH METHODS

We searched the CENTRAL, MEDLINE, Scopus as well as ICTRP Search Portal and ClinicalTrials.gov. The date of the last search of all databases was 18 December 2020.

SELECTION CRITERIA

We included randomised controlled clinical trials (RCTs) comparing the effects of rhTSH-aided radioiodine treatment compared with radioiodine alone for non-toxic multinodular goitre, with at least 12 months of follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance. Screening for inclusion, data extraction, and risk of bias assessment were carried out by one review author and checked by a second. Our main outcomes were health-related quality of life (QoL), hypothyroidism, adverse events, thyroid volume, all-cause mortality, and costs. We used a random-effects model to perform meta-analyses, and calculated risk ratios (RRs) for dichotomous outcomes, and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We evaluated the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included six RCTs. A total of 197 participants were allocated to rhTSh-aided radioiodine therapy, and 124 participants were allocated to radioiodine. A single dose of radioiodine was administered 24 hours after the intramuscular injection of a single dose of rhTSH. The duration of follow-up ranged between 12 and 36 months. Low-certainty evidence from one study, with 85 participants, showed uncertain effects for QoL for either intervention. RhTSH-aided radioiodine increased hypothyroidism compared with radioiodine alone (64/197 participants (32.5%) in the rhTSH-aided radioiodine group versus 15/124 participants (12.1%) in the radioiodine alone group; RR 2.53, 95% CI 1.52 to 4.20; 6 studies, 321 participants; moderate-certainty evidence in favour of radioiodine alone). A total of 118/197 participants (59.9%) in the rhTSH-aided radioiodine group compared with 60/124 participants (48.4%) in the radioiodine alone group experienced adverse events (random-effects RR 1.24, 95% CI 0.94 to 1.63; 6 studies, 321 participants; fixed-effect RR 1.23, 95% CI 1.02 to 1.49 in favour of radioiodine only; low-certainty evidence). RhTSH-aided radioiodine reduced thyroid volume with a MD of 11.9% (95% CI 4.4 to 19.4; 6 studies, 268 participants; moderate-certainty evidence). One study with 28 participants reported one death in the radioiodine alone group (very-low certainty evidence). No study reported on costs.

AUTHORS' CONCLUSIONS

RhTSH-aided radioiodine treatment for non-toxic multinodular goitre, compared to radioiodine alone, probably increased the risk of hypothyroidism but probably led to a greater reduction in thyroid volume. Data on QoL and costs were sparse or missing.

Prevalence and Treatment Outcomes of Marine-Lenhart Syndrome in Japan

INTRODUCTION

Marine-Lenhart syndrome (MLS) is now understood to be a combination of Graves' disease and autonomously functioning thyroid nodule(s) (AFTNs). The prevalence of the syndrome and suitable treatments for those living in iodine-sufficient areas are uncertain.

OBJECTIVES

We aimed to investigate the prevalence, treatment, and prognosis of MLS in Japan, an iodine-sufficient area.

METHODS

This study involved patients who visited our hospital between February 2005 and August 2019. Among patients with both thyrotoxicosis and thyroid nodule(s) larger than 10 mm, MLS and isolated AFTNs were diagnosed based on serum thyroid-stimulating hormone receptor antibody levels and scintigraphy using radioiodine or technetium-99m and thyroid uptake.

RESULTS

Twenty-two patients were found to have MLS, compared to 372 with isolated AFTNs and 8,343 with Graves' disease, during the period. Therefore, the rate of MLS cases was 0.26% among all patients with Graves' disease (22/8,343). Treatments and outcomes were assessed for cases of MLS (n = 18) and isolated AFTNs (n = 269). Antithyroid drugs (ATDs) were withdrawn in 27.8% of cases in the MLS group and 10.3% in the isolated AFTN group. There was no significant difference in the clinical outcome after ATD withdrawal between the 2 groups. However, the rate of hypothyroidism after radioactive iodine (RAI) administration was significantly higher in the MLS group than in the isolated AFTN group (42.9 vs. 9.0%, p = 0.005) despite similar doses of RAI.

CONCLUSIONS

The prevalence of MLS among patients with Graves' disease was 0.26% in Japan. RAI therapy induces hypothyroidism more frequently than in those with AFTNs probably because RAI is taken up in the surrounding Graves' tissues.

2021 European Thyroid Association Guidelines for the Management of Iodine-Based Contrast Media-Induced Thyroid Dysfunction

Given the fact that a large number of radiological examinations using iodine-based contrast media (ICM) are performed in everyday practice, clinicians should be aware of potential ICM-induced thyroid dysfunction (TD). ICM can induce hyperthyroidism (Hyper) or hypothyroidism (Hypo) due to supraphysiological concentrations of iodine in the contrast solution. The prevalence of ICM-induced TD varies from 1 to 15%. ICM-induced Hyper is predominantly found in regions with iodine deficiency and in patients with underlying nodular goiter or latent Graves' disease. Patients at risk for ICM-induced Hypo include those with autoimmune thyroiditis, living in areas with sufficient iodine supply. Most cases of ICM-induced TD are mild and transient. In the absence of prospective clinical trials on the management of ICM-induced TD, an individualized approach to prevention and treatment, based on patient's age, clinical symptoms, pre-existing thyroid diseases, coexisting morbidities and iodine intake must be advised. Treatment of ICM-induced Hyper with antithyroid drugs (in selected cases in combination with sodium perchlorate) should be considered in patients with severe or prolonged hyperthyroid symptoms or in older patients with underlying heart disease. It is debated whether preventive therapy with methimazole and/or perchlorate prior to ICM administration is justified. In ICM-induced overt Hypo, temporary levothyroxine may be considered in younger patients with symptoms of Hypo, with an underlying autoimmune thyroiditis and in women planning pregnancy. Additional clinical trials with clinically relevant endpoints are warranted to further aid in clinical decision-making in patients with ICM-induced TD.

Evaluation of the role of thyroid scintigraphy in the differential diagnosis of thyrotoxicosis

OBJECTIVE

A differential diagnosis of thyrotoxicosis is crucial as the treatment of the main causes of this condition can vary significantly. Recently published diagnostic guidelines on thyrotoxicosis embrace the presence of thyrotropin receptor (TSH-R) antibodies (TRAb) as the primary and most important diagnostic step. The application of diagnostic algorithms to aid in the treatment of hyperthyroidism supports using thyroid radionuclide scintigraphy (TRSt) in baffling clinical scenarios, when TRAb are absent or when third-generation TRAb are not available. First-generation TRAb measurement may have limitations. Consequently, patients with thyrotoxicosis and first-generation TRAb results may be misdiagnosed and consequently improperly treated. Our purpose was to compare first-generation TRAb values to TRSt in the differential diagnosis of hyperthyroidism.

METHODS

We conducted a retrospective study of 201 untreated outpatients with overt or subclinical hyperthyroidism on whom first-generation TRAb and TRSt had been performed at the time of diagnosis. Histological specimens were analysed in patients who had previously undergone thyroid surgery at our centre. SPSS 20.0 was used in statistical analysis.

RESULTS

Seventy-three out of 201 (36.3%) patients had positive TRAb. A diffuse uptake was present in 83.5% (61/73), whereas 13.7% (10/73) had a heterogeneous uptake and 2.7% (2/73) had an absent uptake. Thirty out of 91 (33%) patients with diffuse uptake were negative for positive TRAb and were diagnosed with Graves' disease. Analysis of 37 histological specimens indicated that TRSt had greater accuracy (81% vs 75.7%) and specificity (79.2% vs 57.1%) when compared to TRAb in the differential diagnosis of thyrotoxicosis. However, TRSt sensitivity was inferior to TRAb (84.6% vs 92.3%).

CONCLUSIONS

Our study endorses that initial differential diagnosis of thyrotoxicosis should not be based solely on first-generation TRAb as this approach may leave nearly 20% of the patients misdiagnosed and, consequently, improperly treated. Our results underscore that thyroid scintigraphy should also be performed when only first-generation TRAb assays are available during the initial differential diagnosis of thyrotoxicosis.

Diagnostic testing for Graves' or non-Graves' hyperthyroidism: A comparison of two thyrotropin receptor antibody immunoassays with thyroid scintigraphy and ultrasonography

OBJECTIVE

Graves' disease (GD) is the most common cause of hyperthyroidism. In many cases, when the aetiological diagnosis of GD is not evident based on the clinical evaluation and thyroid function testing, it may become challenging to distinguish Graves' hyperthyroidism from other forms of thyrotoxicosis. The current study was primarly carried out to compare the diagnostic effectiveness of two TSH receptor antibody immunoassays (IMAs), ultrasonography and thyroid scintigraphy in hyperthyroidism scenario.

METHODS

We retrospectively analysed consecutive patients with newly diagnosed and untreated thyrotoxicosis who underwent thyroid functional tests, both TRAb and TSI measurements, thyroid scintigraphy and ultrasonography. TRAb assessment was carried out by Kryptor^® compact PLUS, while TSI by Immulite^® . Echo pattern 3 corresponded to 'thyroid inferno', and the final diagnosis of GD vs non-Graves' hyperthyroidism was made according to the thyroid scan (qualitative scintigraphy). Receiver operating characteristic (ROC) curves were drawn using the final diagnosis as reference. Clinical sensitivity and specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated for all the tests.

RESULTS

A total of 124 untreated hyperthyroid patients were included in our study (GD, n = 86 vs non-Graves' hyperthyroidism, n = 38). ROC curves showed that the optimal cut-off values associated with the highest diagnostic sensitivity and specificity was 0.7 IU/L for TRAb Kryptor^® (93 [85.4-97.4] and 86.8 [71.9-95.5]) and 0.1 IU/L for TSI Immulite^® (94.2 [86.9-98.1] and 84.2 [68.7-93.9]), respectively. For the echo pattern 3, we found a good sensitivity (92.1%) and a high PPV (95.2%) but a quite low specificity value (69.8%) and a relative low NPV (57.5%). For thyroid scintigraphy, the TcTU cut-off value of 1.3% corresponded to the best limit for sensitivity and specificity in our patients (95.3 [88.5-98.7] and 96.4 [81.6-99.4]). The Passing-Bablok regression equation and the Bland-Altman test showed a great degree of correlation and agreement existed between TRAb Kryptor^® and Immulite^® TSI results.

CONCLUSIONS

Thyroid scintigraphy remains the most accurate method to differentiate causes of thyrotoxicosis. However, TRAb assays can be alternatively adopted in this setting, limiting the use of thyroid scintigraphy (TcTU evaluation) to TRAb-negative patients. Thyoid US is less accurate than both TRAb/TSI and thyroid scintigraphy, but the 'thyroid inferno' pattern provides a high PPV for GD.

Thyrotoxicosis: Diagnosis and Management

Thyrotoxicosis is the clinical manifestation of excess thyroid hormone action at the tissue level due to inappropriately high circulating thyroid hormone concentrations. Hyperthyroidism, a subset of thyrotoxicosis, refers specifically to excess thyroid hormone synthesis and secretion by the thyroid gland. We performed a review of the literature on these topics utilizing published data in PubMed and MEDLINE. In this review, we discuss the more common etiologies of thyrotoxicosis, focusing on the current approach to diagnosis and management, new trends in those directions, and potential upcoming changes in the field.

Thyrotropin Receptor Antibodies-An Overview

PURPOSE

Thyroid autoimmunity affects approximately 5% of the population, and its investigation relies heavily on the use of autoantibodies. Thyroid stimulating hormone receptor (TSHR) autoantibodies (TRAb) play a central role in the evaluation of Graves disease (GD), Graves ophthalmopathy (GO) and pretibial myxedema (PTM). However, there is still controversy regarding overall TRAb assay diagnostic accuracy and their prognostic utility.

METHODS

We reviewed and analyzed the literature reporting TRAb assays and their clinical utility.

RESULTS

Current assays measure the overall TRAb titer in a competitive manner (TSH binding inhibiting immunoglobulin assay) or biologic activity of the stimulating TSHR autoantibodies (thyroid stimulating immunoglobulin assay). Both types of assays have improved over time with advances in sensitivity and specificity. TRAb are particularly relevant in hyperthyroidism cases where use of iodinated contrast is not an option (e.g., pregnancy or recent use of iodinated contrast) or in cases of euthyroid eye disease, suspicious for GO. Third generation TRAb assays are useful for therapy selection in GD, prognostic predictions in GO and risk prediction for fetal and neonatal thyrotoxicosis.

DISCUSSION

Given the pathogenic role of TRAb, we expect that the future will bring useful evidence regarding their predictive role with respect to efficacy of therapeutic modalities for GO and PTM. We also hope to better understand the role of blocking and neutral antibodies against TSHR, and harness that ability for modulation of thyroid function or therapy of differentiated thyroid carcinoma managed with TSH suppression.

CONCLUSIONS

Thyroid autoimmune diseases have seen tremendous gains in understanding their pathophysiology, largely antibody mediated. Better TRAb testing is becoming a springboard for providing individualized patient care.

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves' disease

Thyroid hormones are essential developmental factors, and Graves' disease (GD) may severely complicate a pregnancy. This review describes how pregnancy changes the risk of developing GD, how early pregnancy by several mechanisms leads to considerable changes in the results of the thyroid function tests used to diagnose hyperthyroidism, and how these changes may complicate the diagnosing of GD. Standard therapy of GD in pregnancy is anti-thyroid drugs. However, new studies have shown considerable risk of birth defects if these drugs are used in specific weeks of early pregnancy, and this should be taken into consideration when planning therapy and control of women who may in the future become pregnant. Early pregnancy is a period of major focus in GD, where pregnancy should be diagnosed as soon as possible, and where important and instant change in therapy may be warranted. Such change may be an immediate stop of anti-thyroid drug therapy in patients with a low risk of rapid relapse of hyperthyroidism, or it may be an immediate shift from methimazole/carbimazole (with risk of severe birth defects) to propylthiouracil (with less risk), or maybe to other types of therapy where no risk of birth defects have been observed. In the second half of pregnancy, an important concern is that not only the mother with GD but also her foetus should have normal thyroid function.

2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This document describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

METHODS

The American Thyroid Association (ATA) previously cosponsored guidelines for the management of thyrotoxicosis that were published in 2011. Considerable new literature has been published since then, and the ATA felt updated evidence-based guidelines were needed. The association assembled a task force of expert clinicians who authored this report. They examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to update the 2011 text and recommendations. The strength of the recommendations and the quality of evidence supporting them were rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' orbitopathy; and management of other miscellaneous causes of thyrotoxicosis. New paradigms since publication of the 2011 guidelines are presented for the evaluation of the etiology of thyrotoxicosis, the management of Graves' hyperthyroidism with antithyroid drugs, the management of pregnant hyperthyroid patients, and the preparation of patients for thyroid surgery. The sections on less common causes of thyrotoxicosis have been expanded.

CONCLUSIONS

One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY, AND ASSOCIAZIONE MEDICI ENDOCRINOLOGI MEDICAL GUIDELINES FOR CLINICAL PRACTICE FOR THE DIAGNOSIS AND MANAGEMENT OF THYROID NODULES--2016 UPDATE

Thyroid nodules are detected in up to 50 to 60% of healthy subjects. Most nodules do not cause clinically significant symptoms, and as a result, the main challenge in their management is to rule out malignancy, with ultrasonography (US) and fine-needle aspiration (FNA) biopsy serving as diagnostic cornerstones. The key issues discussed in these guidelines are as follows: (1) US-based categorization of the malignancy risk and indications for US-guided FNA (henceforth, FNA), (2) cytologic classification of FNA samples, (3) the roles of immunocytochemistry and molecular testing applied to thyroid FNA, (4) therapeutic options, and (5) follow-up strategy. Thyroid nodule management during pregnancy and in children are also addressed. On the basis of US features, thyroid nodules may be categorized into 3 groups: low-, intermediate-and high-malignancy risk. FNA should be considered for nodules ≤10 mm diameter only when suspicious US signs are present, while nodules ≤5 mm should be monitored rather than biopsied. A classification scheme of 5 categories (nondiagnostic, benign, indeterminate, suspicious for malignancy, or malignant) is recommended for the cytologic report. Indeterminate lesions are further subdivided into 2 subclasses to more accurately stratify the risk of malignancy. At present, no single cytochemical or genetic marker can definitely rule out malignancy in indeterminate nodules. Nevertheless, these tools should be considered together with clinical data, US signs, elastographic pattern, or results of other imaging techniques to improve the management of these lesions. Most thyroid nodules do not require any treatment, and levothyroxine (LT4) suppressive therapy is not recommended. Percutaneous ethanol injection (PEI) should be the first-line treatment option for relapsing, benign cystic lesions, while US-guided thermal ablation treatments may be considered for solid or mixed symptomatic benign thyroid nodules. Surgery remains the treatment of choice for malignant or suspicious nodules. The present document updates previous guidelines released in 2006 and 2010 by the American Association of Clinical Endocrinologists (AACE), American College of Endocrinology (ACE) and Associazione Medici Endocrinologi (AME).

The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism

Endogenous subclinical hyperthyroidism (SHyper) is caused by Graves' disease, autonomously functioning thyroid nodules and multinodular goitre. Its diagnosis is based on a persistently subnormal serum thyroid-stimulating hormone (TSH) level with free thyroid hormone levels within their respective reference intervals. In 2014 the European Thyroid Association Executive Committee, given the controversies regarding the treatment of Endo SHyper, formed a task force to develop clinical practice guidelines based on the principles of evidence-based medicine. The task force recognized that recent meta-analyses, including those based on large prospective cohort studies, indicate that SHyper is associated with increased risk of coronary heart disease mortality, incident atrial fibrillation, heart failure, fractures and excess mortality in patients with serum TSH levels <0.1 mIU/l (grade 2 SHyper). Therefore, despite the absence of randomized prospective trials, there is evidence that treatment is indicated in patients older than 65 years with grade 2 SHyper to potentially avoid these serious cardiovascular events, fractures and the risk of progression to overt hyperthyroidism. Treatment could be considered in patients older than 65 years with TSH levels 0.1-0.39 mIU/l (grade 1 SHyper) because of their increased risk of atrial fibrillation, and might also be reasonable in younger (<65 years) symptomatic patients with grade 2 SHyper because of the risk of progression, especially in the presence of symptoms and/or underlying risk factors or co-morbidity. Finally, the task force concluded that there are no data to support treating SHyper in younger asymptomatic patients with grade 1 SHyper. These patients should be followed without treatment due to the low risk of progression to overt hyperthyroidism and the weaker evidence for adverse health outcomes.

Double vision is a major manifestation in moderate to severe graves' orbitopathy, but it correlates negatively with inflammatory signs and proptosis

CONTEXT

Double vision (diplopia) is a major determinant of work disability in patients with Graves' orbitopathy (GO), but is not part of the classification NOSPECS classification of GO.

OBJECTIVE

The objectives of the study were to quantitate diplopia in patients with moderate to severe GO and to study associations with other disease and patient variables.

DESIGN

This was a single-center prospective study of consecutive patients at the time of referral.

SETTING

The study was conducted at the University Hospital Thyroid-Eye Clinic.

PATIENTS

Patients included 216 patients diagnosed with moderate to severe and active GO.

MAIN OUTCOME MEASURES

Binocular diplopia in field of gaze and monocular fields of motility were prospectively recorded on diagrams and measured by planimetry. Fields of diplopia were correlated to other disease and patient variables.

RESULTS

Six patients had only one functional eye and were excluded. Among the remaining 210 patients, diplopia was present in 75.2%. In patients with diplopia, this ranged from 5% to 100% (observed in 11.4% of patients) of binocular field of gaze. The field of diplopia correlated positively with eye motility restriction and with asymmetrical affection of orbits but negatively with signs of inflammation and proptosis that often are the main outcome measures in clinical studies of GO therapy.

CONCLUSION

Diplopia is very common in moderate to severe GO and a major cause for active therapy. In moderate to severe GO, the field of diplopia correlates negatively with some other indicators of disease activity, which may be explained by the physiological properties of binocular fusion.

Relapse following antithyroid drug therapy for Graves' hyperthyroidism

PURPOSE OF REVIEW

In most patients with hyperthyroidism caused by Graves' disease, antithyroid drug (ATD) therapy is followed by a gradual amelioration of the autoimmune abnormality, but about half of the patients will experience relapse of hyperthyroidism when the ATDs are withdrawn after a standard 1 to 2 years of therapy. This is a major drawback of ATD therapy, and a major concern to patients. We review current knowledge on how to predict and possibly reduce the risk of such relapse.

RECENT FINDINGS

Several patient and disease characteristics, as well as environmental factors and duration of ATD therapy, may influence the risk of relapse after ATD withdrawal. Depending on the presence of such factors, the risk of relapse after ATD withdrawal may vary from around 10 to 90%. Risk factors for relapse should be taken into account when choosing between therapeutic modalities in a patient with newly diagnosed disease, and also when discussing duration of ATD therapy.

SUMMARY

Prolonged low-dose ATD therapy may be feasible in patients with high risk of relapse, such as children and patients with active Graves' orbitopathy, and in patients with previous relapse who prefer such therapy rather than surgery or radioiodine.

Long-term prognosis after medical treatment of Graves' disease in a northern Swedish population 2000-2010

OBJECTIVE

To investigate the long-term prognosis of patients with Graves' disease (GD) after antithyroid drug (ATD) treatment and follow-up outside of highly specialised care.

DESIGN AND METHODS

Medical records of all patients diagnosed with first-time GD in 2000-2010 with at least 6 months ATD treatment at a central hospital and follow-up in primary health care in the county of Norrbotten in northern Sweden were retrospectively reviewed. Patients were followed for relapse until 31st December 2012. We included 219 patients (mean age 46 years, 82.5% women) with follow-up of maximum 10 years and 829 observed patient years. Data were analysed using Kaplan-Meier estimates and log-rank test.

RESULTS

During the observation period, 43.5% of the patients had relapsed into active GD. The cumulative relapse rates were 22.6, 30.2, 36.9 and 41.5% after 6 months, 1, 3 and 5 years respectively. The presence of goitre (P=0.014) predicted relapse. Previous smoking was protective against relapse (P=0.003). The levels of free thyroxine or free tri-iodothyronine, age, gender, current smoking and ophthalmopathy did not predict relapse. Agranulocytosis was found in 1.7% (95% CI 0.7-4.0%).

CONCLUSION

A long-term remission of 56.5%, in an iodine-sufficient area where ATD is offered to most patients in the real world of central and district hospitals, is higher than in most studies. Relapse was most common during the first year, and prognosis was excellent after 4 years without relapse. The protective effect of previous smoking merits further research.

The diagnosis and management of hyperthyroidism in Korea: consensus report of the korean thyroid association

Hyperthyroidism is one of the causes of thyrotoxicosis and the most common cause of hyperthyroidism in Korea is Graves disease. The diagnosis and treatment of Graves disease are different according to geographical area. Recently, the American Thyroid Association and the American Association of Clinical Endocrinologists suggested new management guidelines for hyperthyroidism. However, these guidelines are different from clinical practice in Korea and are difficult to apply. Therefore, the Korean Thyroid Association (KTA) conducted a survey of KTA members regarding the diagnosis and treatment of hyperthyroidism, and reported the consensus on the management of hyperthyroidism. In this review, we summarized the KTA report on the contemporary practice patterns in the diagnosis and management of hyperthyroidism, and compared this report with guidelines from other countries.

Determinants of serum T4 and T3 at the time of diagnosis in nosological types of thyrotoxicosis: a population-based study

OBJECTIVE

To characterize thyroid hormone levels at the time of diagnosis in the nosological types of thyrotoxicosis diagnosed in the population and to analyze determinants for serum thyroxine (T4) and tri-iodothyronine (T3).

DESIGN

Population-based study of thyrotoxicosis at disease onset.

METHODS

In the period 1997-2000, we prospectively identified all patients diagnosed with incident primary overt thyrotoxicosis in a Danish population cohort and classified patients into ten well-defined nosological types of disease (n=1082). Untreated levels of serum T3, T4, and T3:T4 ratio were compared and related to sex, age, level of iodine deficiency, smoking status, alcohol intake, iodine supplement use, co-morbidity, and TSH receptor antibodies (TRAbs) in multivariate models.

RESULTS

Graves' disease (GD) patients had much higher levels of T3 and higher T3:T4 ratio at diagnosis compared with other thyrotoxic patients, but with a profound negative association between hormone levels and age. In GD, patients diagnosed in the area with more severe iodine deficiency had lower levels of T3 and T4. TRAb-negative GD patients had biochemically mild thyrotoxicosis. Higher age was also associated with lower degree of biochemical thyrotoxicosis in nodular toxic goiter. We found no association between serum T3 and T4 and sex, smoking habits, iodine supplements, alcohol intake, or co-morbidity in any type of thyrotoxicosis.

CONCLUSIONS

The study gives new insight into the hormonal presentation of thyrotoxicosis and showed that young age, positive TRAb levels, but also residency in the area with higher iodine intake was positively associated with biochemical disruption in GD.

Clinical review: Clinical utility of TSH receptor antibodies

CONTEXT

TSH receptor antibodies (TRAb) cause Graves' disease (GD) hyperthyroidism. Widely available TRAb measurement methods have been significantly improved recently. However, the role of TRAb measurement in the differential diagnosis of hyperthyroidism, the prediction of remission of GD hyperthyroidism, the prediction of fetal/neonatal thyrotoxicosis, and the clinical assessment of Graves' ophthalmopathy (GO) are controversial.

EVIDENCE ACQUISITION

We reviewed and analyzed the literature reporting primary data on the clinical use of TRAb. We focused our analyses on clinical studies analyzing third-generation TRAb assays.

EVIDENCE SYNTHESIS

The performance of TRAb in the differential diagnosis of overt hyperthyroidism is excellent, with sensitivity and specificity in the upper 90%. TRAb can accurately predict short-term relapses of hyperthyroidism after a course of antithyroid drugs but are less effective in predicting long-term relapses or remissions. Pregnancies in women with GD with negative TRAb are highly unlikely to result in fetal hyperthyroidism, whereas high titers of TRAb in pregnancy require careful fetal monitoring. GD patients with GO frequently have high TRAb levels. However, there are insufficient data to use the test to predict the clinical course of GO and response to treatment.

CONCLUSIONS

Third-generation TRAb assays are suitable in the differential diagnosis of hyperthyroidism. In GD, TRAb should be tested before deciding whether methimazole can be stopped. TRAb should be used in pregnant women with GD to assess the risk of fetal thyrotoxicosis. The use of TRAb in GO requires further studies.

TSH receptor autoantibody immunoassay in patients with Graves' disease: improvement of diagnostic accuracy over different generations of methods. Systematic review and meta-analysis

BACKGROUND

TSH receptor antibodies (TRAb) are the diagnostic hallmark of Graves' disease (GD) and immunoassays for their detection have been available for more than 30 years over three generations of laboratory methods. Despite a growing body of data produced by clinical and laboratory research which demonstrates its elevated sensitivity and specificity, TRAb testing is poorly used for diagnosing GD. The aim of our systematic review and meta-analysis is to verify the diagnostic performance of TRAb detected with 2nd and 3rd generation immunoassay methods.

METHODS

We searched for English articles using MEDLINE with the search terms "TSH receptor antibody assay", "TSH Receptor antibody tests" and "Graves' disease". We analyzed studies reporting on TSH receptor antibody tests performed by quantitative immunoassays, on untreated patients with GD as the index disease (sensitivity) and on a control group of either healthy subjects or patients affected by other thyroid diseases (specificity). A total of 681 titles were initially identified with the search strategy described. 560 publications were excluded based on abstract and title. Full-text review was undertaken as the next step on 111 publications providing data on TRAb testing; 58 articles were subsequently excluded because they did not include untreated GD patients, or used either bioassays or 1st generation immunoassays. 32 were also excluded because they included data only on sensitivity or only on specificity of the assay, or were duplicates. Finally, 21 articles were selected for meta-analysis. Extraction of data from selected articles was performed by two authors independently, using predefined criteria: the number of patients with GD and the number of healthy or diseased controls; specification of the analytical method used to detect TRAb; sensitivity and specificity of the assay.

RESULTS

The meta-analysis showed that the overall pooled sensitivity and specificity of the 2nd and 3rd generation TRAb assays are 97.1% and 97.4%, and 98.3% and 99.2%, respectively, with little difference between the types of immunoassay methods employed (human or porcine receptor, manual or automated procedure). The likelihood of a TRAb-positive individual to have GD is 1367- to 3420-fold greater (depending upon the type of assay) compared to a TRAb-negative person.

CONCLUSIONS

Data from the meta-analysis showed that TRAb measured with 2nd and 3rd generation immunoassay methods have very high sensitivity and specificity in the diagnosis of GD. The difference between 2nd and 3rd generation methods is small and is equally useful. In contrast with recommendations made by clinical endocrinologists who are not familiar with the state of the art in diagnostic technologies of autoimmunology laboratories, we propose a wide application of these tests in clinical practice to screen all hyperthyroid patients.

Development of anti-neutrophil cytoplasmic antibody-associated vasculitis in a patient with Graves' disease independent of anti-thyroid drug therapy

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) in patients with Graves' disease (GD) is linked with the use of anti-thyroid drugs (ATDs). We report the co-occurrence of AAV and GD in a patient that was independent of ATD therapy. A 38-year-old white male presented with systemic symptoms, palpitations, tremors, purpuric skin lesions, and digital pain. Physical examination and biological tests confirmed GD. He quickly developed multiple digital gangrenes and testicular pain/mass. Skin and testicular biopsies showed granulomatous vasculitis of the small- and medium-sized vessels, while his serum contained anti-proteinase-3 antibody.

Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists

OBJECTIVE

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This article describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.

METHODS

The development of these guidelines was commissioned by the American Thyroid Association in association with the American Association of Clinical Endocrinologists. The American Thyroid Association and American Association of Clinical Endocrinologists assembled a task force of expert clinicians who authored this report. The task force examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to develop the text and a series of specific recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' ophthalmopathy; and management of other miscellaneous causes of thyrotoxicosis.

CONCLUSIONS

One hundred evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

Sustained control of Graves' hyperthyroidism during long-term low-dose antithyroid drug therapy of patients with severe Graves' orbitopathy

BACKGROUND

Patients with severe Graves' orbitopathy often have hyperthyroidism that is difficult to treat and a high proportion of patients experience relapse of hyperthyroidism after a course of antithyroid drug (ATD) therapy of fixed duration. The aim of the study was to evaluate the feasibility of prolonged low-dose ATD therapy for attaining stable euthyroidism in patients with severe Graves' orbitopathy and hyperthyroidism.

METHODS

We performed retrospective analyses of data collected during observation of a cohort of patients (n = 108) treated for severe Graves' orbitopathy and for hyperthyroidism using partial block with low-dose thionamide + replacement with levothyroxine (L-T4) for >2 years. The study was performed at a university hospital referral center for patients with severe Graves' orbitopathy.

RESULTS

The median duration of thionamide therapy was 80 months (25-75 percentiles: 55-115 months); 101 patients received methimazole (median: 5 mg/day) without side effects during prolonged therapy, and 7 propylthiouracil (median: 200 mg/day); median L-T4 dose was 0.1 mg/day. Ninety percent of patients remained euthyroid throughout the period of therapy, and 65% of them had thyroid stimulating hormone (TSH) receptor antibodies in serum within the assay reference interval at the last observation. Only four (3.7%) developed episodes of hyperthyroidism during stable therapy, and 94% had serum TSH within 0.1-4.0 mU/L at the last observation. One patient developed reversible cutaneous vasculitis after 6 years of propylthiouracil therapy.

CONCLUSIONS

Prolonged partial block plus replacement therapy with low-dose ATD + L-T4 keeps the majority of patients with severe Graves' orbitopathy and hyperthyroidism stable and euthyroid.

Performance of a third-generation TSH-receptor antibody in a UK clinic

BACKGROUND

UK national guidelines recommend the measurement of TSH receptor antibodies (TRAb) in certain clinical scenarios. A commercial third-generation TRAb autoantibody M22-biotin ELISA assay was introduced in May 2008 in our centre.

OBJECTIVE

To evaluate the diagnostic performance of a TRAb assay in a retrospective and subsequently a prospective cohort in a UK centre.

DESIGN

A retrospective review of patients with thyroid disease followed by a prospective observational study in consecutive patients with newly found suppressed serum thyrotrophin (TSH).

PATIENTS AND MEASUREMENTS

Medical records of 200 consecutive patients with thyroid disorders who had TRAb measured since the introduction of the assay. In a prospective study 44 patients with newly identified hyperthyroidism (TSH < 0·02 mIU/l) had sera assayed for TRAb prior to their clinic appointment at which a final diagnosis was sought.

RESULTS

In the retrospective cohort, the manufacturer's cut-off point of TRAb ≥0·4 U/l resulted in a positive predictive value (PPV) of 95%, sensitivity 85%, specificity 94% and negative predictive value (NVP) 79% to diagnose Graves' disease using defined criteria. Receiver operating characteristic (ROC) analysis determined an optimal cut-off point of TRAb ≥3·5 U/l with a 100% specificity to exclude patients without Graves' disease at the cost though of a lower sensitivity (43%). In the prospective study, the sensitivity, PPV, specificity and NPV were all 96% using the ≥0·4 U/l cut-off. When combining hyperthyroid patients from both cohorts the assay sensitivity and specificity at ≥0·4 U/l cut-off were 95% and 92% respectively. A positive TRAb result increased the probability of Graves' disease for a particular patient by 25-35% and only six (2·5%) patients had a diagnosis of hyperthyroidism of uncertain aetiology after TRAb testing.

CONCLUSIONS

The assay studied specifically identifies patients with Graves' disease. It is a reliable tool in the initial clinical assessment to determine the aetiology of hyperthyroidism and has the potential for cost-savings.

The role of TSH receptor antibodies in the management of Graves' disease

The central role of thyrotropin receptor antibodies (TRAbs) in the pathogenesis of Graves' disease has been recognised for several decades. However, the practical application of testing for TRAbs in clinical decision making remains the subject of controversy. The diagnosis of Graves' disease can be made in most cases simply based on a patient's clinical presentation. The TRAb test is therefore of most value in ambiguous clinical scenarios such as in the differential diagnosis of unilateral exophthalmos, euthyroid Graves' ophthalmopathy, subclinical hyperthyroidism, thyrotoxicosis associated with hyperemesis gravidarum, amiodarone-induced thyrotoxicosis and painless thyroiditis. It may also have a role in predicting the risk of a recurrence of Graves' disease following a course of antithyroid drug treatment. One further clinical utility of the TRAb test is in pregnancy where antibody titre measured during the third trimester is used to predict the risk of neonatal thyroid dysfunction. The TRAb titre not only aids in clinching a difficult diagnosis but can also help guide treatment in some patients. Although the TRAb assay has become more affordable in recent years, cost remains an important factor when considering its use routinely. Nonetheless, this is an underutilised blood test that could augment standard endocrine investigations in the differential diagnosis of hyperthyroidism.

Hyperthyroidism and other causes of thyrotoxicosis: management guidelines of the American Thyroid Association and American Association of Clinical Endocrinologists

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This article describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspeciality physicians and others providing care for patients with this condition.

METHODS

The development of these guidelines was commissioned by the American Thyroid Association in association with the American Association of Clinical Endocrinologists. The American Thyroid Association and American Association of Clinical Endocrinologists assembled a task force of expert clinicians who authored this report. The task force examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to develop the text and a series of specific recommendations. The strength of the recommendations and the quality of evidence supporting each was rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' ophthalmopathy; and management of other miscellaneous causes of thyrotoxicosis.

CONCLUSIONS

One hundred evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

Epidemiology of subtypes of hyperthyroidism in Denmark: a population-based study

OBJECTIVE

Few population-based studies have described the epidemiology of subtypes of hyperthyroidism.

DESIGN

A prospective population-based study, monitoring two well-defined Danish cohorts in Aalborg with moderate iodine deficiency (n=311 102) and Copenhagen with only mild iodine deficiency (n=227 632).

METHODS

A laboratory monitoring system identified subjects with thyroid function tests suggesting overt hyperthyroidism (low s-TSH combined with high s-thyroxine or s-triiodothyronine). For all subjects, we collected information on medical history, thyroid scintigraphy and thyroid hormone receptor antibody (TRAb) measurement. Information was used to disprove or verify primary overt hyperthyroidism and to subclassify hyperthyroidism into nosological disorders.

RESULTS

From 1997 to 2000 (2 027 208 person-years of observation), we verified 1682 new cases of overt hyperthyroidism. The overall standardized incidence rate (SIR) per 100 000 person-years was 81.6, and was higher in Aalborg compared with Copenhagen (96.7 vs 60.0, P<0.001), giving an SIR ratio (SIRR (95% confidence interval (CI))) between moderate versus mild iodine-deficient areas of 1.6 (1.4-1.8). Nosological types of hyperthyroidism (percentage/SIRR (95% CI)): multinodular toxic goitre (MNTG) 44.1%/1.9 (1.6-2.2), Graves' disease (GD) 37.6%/1.2 (0.99-1.4), solitary toxic adenoma (STA) 5.7%/2.4 (1.3-3.5), 'mixed type' hyperthyroidism (TRAb-positive, scintigraphicly multinodular) 5.4%/6.0 (3.0-12), subacute thyroiditis 2.3%/0.9 (0.4-1.4), postpartum thyroid dysfunction 2.2%/1.6 (0.8-3.0), amiodarone-associated hyperthyroidism 0.8%/7.1 (1.1-65), hyperthyroidism after thyroid radiation 0.7%/12.3 (0.8-50), lithium-associated hyperthyroidism 0.7%/0.97 (0.4-4.8) and hyperthyroidism caused by various other factors 0.7%. Lifetime risk for overt hyperthyroidism was 10.5%/6.5%/2.4% (females/all/males).

CONCLUSION

Hyperthyroidism was common in Denmark with MNTG and GD as dominating entities. The higher incidence of hyperthyroidism in the most iodine-deficient region was caused by higher frequency of MNTG, 'mixed-type', STA and amiodarone-associated hyperthyroidism.

Accuracy of receptor-based methods for detection of thyrotropin-receptor autoantibodies: a new automated third-generation immunoassay shows higher analytical and clinical sensitivity for the differential diagnosis of hyperthyroidism

PURPOSE

Specific autoantibodies acting as TSH receptor agonists (TRAb) are responsible for Graves' disease (GD). In the last 30 years three generations of assay methods for the detection of TRAb have become available. The aim of this multicentre study was to evaluate the analytical sensitivity, precision and diagnostic accuracy of TRAb measurement using a new automated assay in comparison with a second-generation standard method.

METHODS

Serum samples from patients with GD (n=82), autoimmune thyroiditis (AIT, n=57) or hyperthyroidism (HT, n=292), from 106 healthy subjects and from 57 patients with infectious diseases were analysed using a third-generation TRAb immunoassay (anti-TSHR, RAD 120; Radim, Italy) based on the human monoclonal TSH receptor antibody M22.

RESULTS

Using a cut-off value of 1.25 mIU/l, established by ROC curve analysis, 80/82 GD patients (97.5%), 68/292 HT patients (23.2%), and 6/57 AIT patients (10.5%) were TRAb-positive with the M22-based automated assay. The percentages of TRAb positivity were lower in the same patients when the measurements were done with the second-generation method (95.1%, 18.9%, 7.0%, respectively).

CONCLUSION

The M22-based automated immunoassay shows high functional sensitivity (0.4 mIU/l) and high diagnostic specificity, is more sensitive than the standard second-generation method and is less time-consuming and labourintensive, and is therefore the up-to-date technology for TRAb detection in clinical practice.

Clinical review about TRAb assay's history

Commercial assays to measure thyroid stimulating hormone (TSH) receptor (TSHR) autoantibodies (TRAb) have been available for the serological diagnosis of autoimmune thyroid diseases (AITD) for several years. The widespread assessment of this parameter has identified Graves' disease (GD) as a common organ-specific autoimmune disease. Within the present article we aim to review immunobiological and epidemiological aspects as well as diagnostic methods available for the detection of TRAb. Over the last decade, TRAb detection in GD became more sensitive since TRAb assays were being largely improved by named research groups. Therefore, functional assay (fas) and diagnostic sensitivity of current TRAb assays will be discussed. Within the second part of this review we will focus on clinical applications of TRAb measurement for outcome prediction of GD as well as the importance of this method to distinguish GD from other AITD.

Assays for thyroid-stimulating hormone receptor antibodies employing different ligands and ligand partners may have similar sensitivity and specificity but are not interchangeable

BACKGROUND

The best biochemical marker of Graves' disease (GD) is the presence in serum of autoantibodies to the thyroid-stimulating hormone receptor (hTSHR-Ab). The aim of this study was to evaluate the performances of two sensitive hTSHR-Ab assays with a specific focus on the clinical importance of differences in results. Both assays are competitive in nature but employ quite different types of ligands. In the "M22-pTSHR" assay, hTSHR-Ab competes with a labeled monoclonal antibody (M22*) against the thyrotropin (TSH)-receptor for binding to porcine TSH receptors. In the "bTSH-rhTSHR" assay, hTSHR-Ab competes with labeled bovine TSH for binding to recombinant human TSH receptors.

METHODS

bTSH-rhTSHR and M22-pTSHR were measured in patients from a population study: 106 had new hyperthyroidism due to GD, 93 had multinodular toxic goiter, 100 had new primary autoimmune hypothyroidism, and 100 were healthy controls.

RESULTS

Receiver operating characteristic curves indicated a high sensitivity and specificity of both assays (area under curve, bTSH-rhTSHR: 0.977 [confidence interval: 0.954-1.00]; M22-pTSHR: 0.979 [confidence interval: 0.957-1.00]). The two assays identified nearly the same patients who were hTSHR-Ab positive, though large differences in hTSHR-Ab values were obtained in a number of individual patients (ratio bTSH-rhTSHR/M22-pTSHR, range: 0.33-6.5 in patients positive with both assays). Values were in average 2.5 times higher with the bTSH-rhTSHR assay compared with the M22-pTSHR assay, corresponding to the difference in recommended clinical cut-off values (1.0 IU/L and 0.4 u/L). The bTSH-rhTSHR assay had a considerably lower intraassay coefficients of variation of 3.8%; for M22-pTSHR, it was 9.5% (p < 0.01).

CONCLUSIONS

Both assays had a high sensitivity and specificity for diagnosing GD. hTSHR-Ab values were in average 2.5 times higher with the bTSH-rhTSHR assay compared with the M22-pTSHR assay. In individual patients, the ratio between results obtained using the two assays varied widely. Thus, results obtained using one assay cannot be quantitatively transformed to values obtained using the other assay. bTSH-rhTSHR had a considerably lower intraassay coefficients of variation and it may be better suited for longitudinal studies of hTSHR-Ab.

Effects of fission neutrons on human thyroid tissues maintained in SCID mice

Morphology and function (secretion of thyroid hormone) of human thyroid tissues from Graves' disease patients are well maintained in C57BL/6J-scid mice. Serum level of thyroid hormone was reduced by fission neutrons from the nuclear reactor UTR-KINKI, and changes in thyroid hormone by fission neutrons were bigger than those by low LET radiations, X-rays and (137)Cs gamma-rays, suggesting high relative biological effectiveness (RBE; 6.5) of fission neutrons. Microarray analyses revealed that about 3% of genes showed more than 4-fold change in gene expression in the unexposed thyroid tissues against surgically resected thyroid tissues from the same patient, probably due to the difficult oxygen and nutrient supply shortly after transplantation. Dose-dependent changes in gene expression against unexposed concurrent controls were observed with increasing doses of fission neutrons (0.2-0.6Gy) and (137)Cs gamma-rays (1.0-3.0Gy) and showed high RBE (4.2). Furthermore, there were some specific genes which showed more than 4-fold change in gene expression in all the thyroid tissues exposed to higher doses of radiation, especially neutrons (0.4 and 0.6Gy), but none at lower doses (0.2Gy of neutrons and 1.0 and 2.0Gy of gamma-rays). These genes related to degeneration, regeneration, apoptosis, and transcription, respond specifically and very sensitively to neutron injury in human thyroid tissues. This is the first experimental report that fission neutrons can induce some morphological and functional disorders in human tissues, showing high RBE against gamma-ray exposure. These results are useful to evaluate the risks of fission neutrons and cosmic rays to humans.

Clinical value of the first automated TSH receptor autoantibody assay for the diagnosis of Graves' disease (GD): an international multicentre trial

BACKGROUND

Most recently, a new rapid and fully automated electrochemiluminescence immunoassay for the determination of TSH receptor autoantibodies (TRAb) based on the ability of TRAb to inhibit the binding of a human thyroid-stimulating monoclonal antibody (M22) has been established.

OBJECTIVE

To evaluate this assay system in clinical routine based on an international multicentre trial and to compare the results with other established TRAb assays.

PATIENTS AND MEASUREMENTS

Totally 508 Graves' disease (GD), 142 autoimmune thyroiditis, 107 subacute thyroiditis, 109 nonautoimmune nodular goitre, 23 thyroid cancer patients and 446 normal controls were retrospectively evaluated.

RESULTS

ROC plot analysis revealed an area under curve of 0.99 (95% CI: 0.99-1.0) indicating a high assay sensitivity and specificity. The highest sensitivity (99%) and specificity (99%) was seen at a cut-off level of 1.75 IU/l. Here, the calculated positive predictive value was 95%, whereas the negative predictive value was 100%. Applying the ROC plot-derived cut-off of 1.75 IU/l we found a sensitivity for TRAb positivity within the group of newly diagnosed GD patients of 97% which is in accordance to the sum of different nonautomated porcine TSH receptor-based assays with a sensitivity of 94% indicating an excellent analytical performance of the new assay format. Detailed comparison of the automated and the sum of manual assays revealed a near identical specificity.

CONCLUSION

Our results demonstrate that this new assay system has a high sensitivity for detecting GD and specificity for discriminating from other thyroid diseases. This assay may represent the future technology for rapid fully automated TRAb detection.

Thyroid volume in hypothyroidism due to autoimmune disease follows a unimodal distribution: evidence against primary thyroid atrophy and autoimmune thyroiditis being distinct diseases

CONTEXT

Primary overt autoimmune hypothyroidism is often divided into primary idiopathic hypothyroidism with thyroid atrophy (Ord's disease) and hypothyroidism with goitre (Hashimoto's disease).

OBJECTIVE

The aim of the present study was to characterize the two subtypes of disease.

DESIGN AND SETTING

This was a population-based study identifying patients newly diagnosed with overt autoimmune hypothyroidism.

PATIENTS

We prospectively identified all patients with incident overt autoimmune hypothyroidism in a Danish population cohort, and 247 patients were invited to join a comprehensive program including thyroid ultrasonography and measurements of thyroid autoantibodies. Of the 144 patients investigated (58% of all invited), 139 were compared with 556 sex-, age-, and region-matched controls from the cohort.

RESULTS

Patients had lower median (11.6 ml vs. 13.5 ml, P = 0.001) and a more dispersed distribution of thyroid volumes compared with controls (P < 0.001). Log thyroid volume showed a Gaussian distribution in both males and females with no bimodal pattern. Nearly all patients had measurable thyroid autoantibodies, but with increasing thyroid volume (quartile I, II, III, and IV), levels of circulating antibodies were higher (median thyroid peroxidase autoantibody 1540, 3122, 4686, and 7058 kU/liter; median thyroglobulin autoantibody 72, 143, 119, and 1195 kU/liter), and thyroid volume correlated negatively with echogenicity (r = -0.21, P = 0.011). Patients with the smallest volumes were biochemically more hypothyroid at diagnosis (median serum T(4) 21.0, 45.5, 45.0, and 36.7 nmol/liter; median serum TSH 81.0, 40.9, 45.4, and 55.6 mU/liter). No difference between groups was observed in prevalence of TSH receptor autoantibody (14.7, 5.6, 14.7, and 8.3%) or duration of symptoms before hypothyroidism was diagnosed.

CONCLUSIONS

In primary autoimmune hypothyroidism, thyroid volume follows a normal distribution. Cases with thyroid atrophy and goiter are only extremes within this distribution and do not represent separate disorders. However, patients with low vs. high thyroid volume differ with respects to several characteristics.

Intermethod Variability in TSH-Receptor Antibody Measurement: Implication for the Diagnosis of Graves Disease and for the Follow-Up of Graves Ophthalmopathy

Background: We compared the analytical and clinical performance of 3 porcine thyroid receptor antibody (TRAb) methods (1 second- and 2 new third-generation systems) with the conventional TRAb assay based on the human recombinant TSH receptor (hTRAK).

Patients and Methods: We obtained sera from 86 patients with untreated Graves disease (GD) and 71 healthy controls. We measured TRAb concentrations by radioreceptor assay using the hTRAK (Brahms) or the porcine TSH receptor (pRRA) from Beckman-Coulter, by electrochemiluminescence immunoassay (ECLIA) with the Elecsys/Cobas (Roche), and by ELISA using the Medizym TRAb clone (Medipan).

Results: Between-run assay imprecision was ≤10% and ≤7.6% for hTRAK and ECLIA, but reached 14% and 14.9% for ELISA and pRRA, respectively. Maximal specificity and sensitivity close to 100% were obtained for hTRAK, ECLIA, and ELISA. pRRA failed to detect positive TRAbs in 5 GD patients. Although calibrated against the same reference standard 90/672, the assays displayed a high intermethod variability. The results were significantly higher by ECLIA and lower by ELISA and pRRA compared with hTRAK. Patients with ophthalmopathy had higher TRAb results by ELISA and pRRA than those without eye disease.

Conclusions: Second- and third-generation TRAb assays had similar diagnostic sensitivities in the diagnostic evaluation of GD. Despite the use of the same reference standard for calibration, high intermethod variability in TRAb assay results was seen in untreated GD patients. Assay harmonization is necessary for correct interpretation in the follow-up of Graves ophthalmopathy.

Technical evaluation of the first fully automated assay for the detection of TSH receptor autoantibodies

BACKGROUND

Graves' disease (GD) is mediated by autoantibodies which bind to the TSH receptor (TRAb). The aim of the present study was to evaluate the technical performance of the first fully automated immunoassay for TRAb detection.

METHODS

The Elecsys Anti-TSHR immunoassay utilizes a porcine TSH receptor (TSHR) and the human thyroid stimulating monoclonal TSHR autoantibody M22.

RESULTS

Intraassay and total imprecision CV were determined between 1.4%-14.9%, and 2.4%-28.8%, respectively. Using the 20% CV criteria the functional sensitivity was found at 0.73 IU/L. The median CV at the cut-off (1.75 IU/L) was found to be 11%. Comparison studies with five TRAb immunoassays yielded slopes and intercepts between 1.02-1.48, and -0.74-0.56, respectively. Correlation coefficients were determined between 0.895 and 0.978. ROC plot analysis of patients with GD, patients with other thyroid disorders and healthy controls revealed an AUC of 0.99 resulting in a sensitivity of 97% and a specificity of 99% at a TRAb level of 1.75 IU/L.

CONCLUSION

The evaluation of the TRAb immunoassay generated homogeneous performance data and demonstrated a high degree of comparability to established TRAb assays. The automated TRAb assay represents a major improvement of thyroid testing in clinical practice.

Frequency and characteristics of TBII-seronegative patients in a population with untreated Graves' hyperthyroidism: a prospective study

OBJECTIVE

It is claimed that second generation thyrotropin-binding inhibitory immunoglobulin (TBII) assays have a very high sensitivity for the diagnosis of Graves' hyperthyroidism (GH). However, studies evaluating the accuracy of TBII have been retrospective in nature and/or GH had not been diagnosed independently of TBII. The aim of the present study, therefore, was to prospectively evaluate the frequency and characteristics of TBII-seronegative patients in a population of untreated GH diagnosed independent of serum TBII.

DESIGN

Prospective multicentre observational study.

PATIENTS

A total of 259 consecutive untreated patients with a first episode of GH, diagnosed independent of serum TBII. TBII levels were measured by second generation assay and correlated to thyroid function, clinical characteristics and exposure to environmental factors.

RESULTS

Serum TBII was positive in 245 (94.6%) patients and negative (< 2 IU/l) in 14 (5.4%) patients. TBII-seronegative patients had lower fT4 (median 42.5 vs. 53.9 pmol/l, P = 0.02), T3 (median 3.55 vs. 4.90 nmol/l, P < 0.01) and fT3-index (median 4.30 vs. 6.27, P < 0.01) compared to TBII-seropositive patients. None of the TBII-seronegative patients had TSH-receptor activating mutations, Graves' orbitopathy or pretibial myxedema. Serum TBII was positively correlated to free T3 (fT3)-index and free T4 (fT4)-index (P < 0.01), goitre size (P < 0.01) and the prevalence of Graves' orbitopathy (P < 0.01). There were no significant differences between TBII-seropositive and TBII-seronegative patients in environmental factors.

CONCLUSION

The prevalence of TBII-seronegativity in untreated patients with GH is 5.4% using a second generation assay. TBII-seronegative patients have biochemically less severe thyrotoxicosis and no Graves' orbitopathy. TBII-seronegative and TBII-seropositive patients apparently belong to the same population of GH, albeit the severity of the autoimmune attack is less in TBII-seronegative patients.

TSH-receptor autoimmunity in Graves' disease after therapy with anti-thyroid drugs, surgery, or radioiodine: a 5-year prospective randomized study

INTRODUCTION

Autoimmunity against the TSH receptor is a key pathogenic element in Graves' disease. The autoimmune aberration may be modified by therapy of the hyperthyroidism.

OBJECTIVE

To compare the effects of the common types of therapy for Graves' hyperthyroidism on TSH-receptor autoimmunity.

METHODS

Patients with newly diagnosed Graves' hyperthyroidism aged 20-55 years were randomized to medical therapy, thyroid surgery, or radioiodine therapy (radioiodine was only given to patients > or = 35 years of age). L-thyroxine (L-T4) was added to therapy as appropriate to keep patients euthyroid. Anti-thyroid drugs were withdrawn after 18 months of therapy. TSH-receptor antibodies (TRAb) in serum were measured before and for 5 years after the initiation of therapy.

RESULTS

Medical therapy (n=48) and surgery (n=47) were followed by a gradual decrease in TRAb in serum, with the disappearance of TRAb in 70-80% of the patients after 18 months. Radioiodine therapy (n=36) led to a 1-year long worsening of autoimmunity against the TSH receptor, and the number of patients entering remission of TSH-receptor autoimmunity with the disappearance of TRAb from serum during the following years was considerably lower than with the other types of therapy.

CONCLUSION

The majority of patients with Graves' disease gradually enter remission of TSH-receptor autoimmunity during medical or after surgical therapy, with no difference between the types of therapy. Remission of TSH-receptor autoimmunity after radioiodine therapy is less common.

TSH receptor antibodies

The discovery of thyroid-stimulating autoantibodies by Adams and Purves 50 years ago was one of the most important observations in the history of thyroidology. Since that time, the thyroid-stimulating hormone receptor (TSHR) has been shown to be the antigen recognized by these autoantibodies (1974) and the receptor cloned (1989). More recently, different mouse monoclonal antibodies (MAbs) to the TSHR have been produced, culminating in 2002 in the preparation of mouse and hamster MAbs with strong thyroid-stimulating activity. Further, in 2003 a human MAb to the TSHR (M22) with the characteristics of patient thyroid-stimulating autoantibodies was described. M22 has been particularly useful in advancing our knowledge of the TSHR and TSHR autoimmunity, including the development of new assays for TSHR autoantibodies (2004) and determination of a high-resolution (2.55 A) crystal structure of the TSHR leucine-rich domain in combination with M22 (2007). The structure shows that M22 positions itself on the TSHR in an almost identical way to the native hormone TSH but the evolutionary forces that have resulted in production of a common autoantibody that mimics the actions of TSH so well are far from clear at this time. Very recently, a human MAb (5C9) with the characteristics of blocking-type patient serum TSHR autoantibodies has been isolated (2007). Studies on how 5C9 interacts with the TSHR at the molecular level are planned and should provide key insights as to the differences between TSHR autoantibodies with blocking and with stimulating activities. Also, 5C9 and similar MAbs have considerable potential as drugs to inhibit TSHR stimulation by autoantibodies. Further, now the M22-TSHR structure is known at the atomic level, rational design of specific low-molecular-weight inhibitors of the TSHR-TSHR autoantibody interaction is feasible.

TSH-receptor antibodies determined by the first, second and third generation assays and thyroid-stimulating antibody in pregnant patients with Graves' disease

The measurement of TSH receptor antibody (TRAb) has been recommended to predict the risk of neonatal hyperthyroidism (NH) in pregnant women with Graves' disease (GD). For the first generation TRAb (TRAb1) assay with commercial kit (Brahms, Berlin, Germany; or Cosmic co., Tokyo, Japan) an arbitrary limit of 40 U/l or 50% was suggested to indicate risk when measured late in pregnancy. In order to substitute TRAb1 with the second generation TRAb using porcine TSH receptor (pTRAb2) and human recombinant TSH receptor (hTRAb2) and the third generation TRAb (TRAb3) assay for this purpose, we measured TRAb in these four methods late in pregnancy in a total of 62 pregnant women with Graves' disease. The data showed that no cases with TRAb1 >50% has been missed if the TRAb1 assay was replaced by the pTRAb2, hTRAb2 or TRAb3 assay using their equivalent cut-off value of 70%, 10 IU/l, and 75%, respectively, but that an additional group of women would have been included in the risk group, especially in the TRAb3 assay. Next, the effect of maternal TRAb on thyroid function of offspring was studied in the 47 pregnant women with GD (43 with TRAb1 <50% and 4 with TRAb1 >50% during late pregnancy). In 2 women who gave birth to hyperthyroid children at days 6 and 14 of life, the maternal sera had strongly positive levels of TRAb1 (73.5% and 84.1%), pTRAb2 (84.9% and 91.5%), hTRAb2 (40.68 IU/L and 89.70 IU/L) and TRAb3 (92.1% and 93.5%) late in pregnancy, with one case displaying high positive (1114.3%) thyroid stimulating antibody (TSAb) level and the other case had moderate positive (433%) TSAb level. Of the remaining 45 women, 43 had TRAb1 <50% and the other 2 had TRAb >50% including 1 with low TSAb positive and 1 with positive thyroid stimulating blocking antibody (TSBAb) and negative TSAb; all of them gave birth to euthyroid children. Finally, a serial study regarding TRAb in 23 women with Graves' disease during pregnancy showed that TRAb1, pTRAb2, hTRAb2, TRAb3 value and TSAb level decreased significantly as pregnancy progressed. In conclusion, the present study supported TRAb as a useful marker to predict the risk of NH.