TSH-binding Inhibitory Immunoglobulin Research Articles

6502 Comparing TBII vs TSI Assays at University Hospital; A Quality Improvement Project

Abstract Disclosure: L.E. Chozet: None. G. Le: None. M.A. Escobar Vasco: None. Radionuclide uptake and scan in the setting of thyrotoxicosis is considered the gold standard test to diagnose Graves' disease (GD). However, TSH-receptor antibodies (TRAB) tests are now being used as optional first-line tests given their widespread availability and cost-effectiveness. Thyrotropin-binding inhibitory immunoglobulin (TBII) and thyroid-stimulating immunoglobulin (TSI) assays are commonly obtained in patients admitted with thyrotoxicosis. Both assays are readily available at our institution. Our project aimed to further review and compare these two assays. To determine turnaround times of these assays at our institution, as well as cost-effectiveness of ordering both TBII and TSI assays vs only ordering one assay. We did a retrospective evaluation of 27 patients with lab evidence of thyrotoxicosis at University Hospital between April 2022, and May 2023 who were tested with both TBII, TSI assays simultaneously during their hospital stay to compare their concordance. We then compared turnaround times in days for laboratory results to be available. TBII, TSI assays are not done in-house. They are instead sent to an outside laboratory. Our hospital pathology services provided us with information regarding lab costs. We investigated which assay is more cost-effective. Based on our data, TBII and TSI were concordant in almost all patients evaluated (26 out of 27). Ordering TBII as the first initial test for GD is more cost-effective than ordering both TSI, TBII simultaneously. Our findings are consistent with previous studies, which suggest that ordering both assays (TBII and TSI) could be reserved for patients where the diagnosis of GD is not clear. Presentation: 6/3/2024

6575 From Tonsils to the Thyroid: A Rare Case of Acute Suppurative Thyroiditis in an Immunocompetent Adult

Abstract Disclosure: F. Sajid: None. A. Mubashir: None. F. Mohsin: None. M. Sattar: None. Introduction: Acute suppurative thyroiditis (AST) is a rare infection of the thyroid gland due to its high vascularity, protective encapsulation, and high iodine content. Most AST cases occur in children with anatomical aberrations or in immunosuppressed adults. Here, we describe a case of AST in an immunocompetent woman. Case: A 54-year-old woman with no medical history presented to the emergency department due to dyspnea, dysphagia, and odynophagia for two days. She reported a four-day history of sore throat, fever, and chills. She was saturating well on room air but was sitting in a tripod position. She had erythema, swelling, tenderness to palpation in the anterior neck with a hoarse voice, and moderate trismus. Nasopharyngoscopy revealed no mass, but the scope could not pass beyond the velum due to edema. The patient’s condition quickly deteriorated, necessitating emergent intubation for acute hypoxic respiratory failure. After intubation, the patient had cardiac arrest with asystole requiring resuscitation and successful ROSC. The initial CT scan showed extensive soft tissue abnormalities in the nasopharynx and parapharyngeal tissues, extending to the thyroid gland and mediastinum with the possibility of developing abscesses. A thyroid ultrasound showed a heterogeneous thyroid gland without nodules or increased vascularity. Treatment commenced with ampicillin-sulbactam. Laboratory results showed Free T4 of 4.74 ng/dL (0.58-1.64), TSH 0.03 MCIU/mL (0.39-4.08), Total T3 1.56 ng/dL (0.72-1.35), WBC 19.3 K/UL (4.8-10.8), and elevated ESR and CRP levels. Thyroid-stimulating Immunoglobulin (TSI), Thyroid Peroxidase (TPO) Antibody, and Thyrotropin Binding Inhibitory Immunoglobulin (TBII) were negative, making AST the top differential. Methimazole was initiated due to concerns of thyroid storm, but it was quickly tapered due to a significant decrease in Free T4 levels and suspicion of AST. A repeat CT scan revealed more defined abscesses along the bilateral pharyngeal walls extending to the thyroid bed. The patient underwent bilateral tonsillectomy and drainage of the abscesses. She was extubated the following day. Cultures from the abscesses grew rare Klebsiella pneumoniae, susceptible to Ampicillin-sulbactam. A barium swallow on day 14 showed no evidence of a pyriform sinus fistula. She was discharged on day 15 with Augmentin for 7 days. On discharge, free T4 decreased to half (2.39 ng/dL), and Total T3 normalized (1.08ng/dL). Conclusion: This case presents a rare instance of AST in an immunocompetent patient without anatomical anomalies, stemming from the spread of peritonsillar and parapharyngeal abscesses into the thyroid bed. AST should be considered in cases of deep neck infections, as it is a potentially life-threatening disease. It is crucial to identify and treat AST early to prevent complications. The primary treatment involves antibiotics, incision, and drainage. Presentation: 6/1/2024

8176 An Unusual Case of Thyroid Eye Disease (TED) Occurring in Autoimmune Hypothyroidism

Abstract Disclosure: K. Prasongdee: None. C.M. Tessier: None. Background: It is unusual for TED to present in patients with autoimmune thyroid disease who are euthyroid or hypothyroid. Clinician recognition of this rare presentation is important in ensuring proper treatment and improving patient outcomes. Clinical Case:Our patient is a 57-year-old female with a past medical history of COPD, hypothyroidism presenting with several months of blurry vision. She reports double vision when looking down, and eye pain at rest and with eye movement. She was diagnosed with hypothyroidism one year prior to presentation, and her TSH subsequently normalized after titration to levothyroxine of 112 mcg daily. She reported no history of head or neck radiation. No family history of thyroid disease. She smoked for 30 pack years but stopped 2 years prior. Physical exam showed eye lid swelling and redness, pain and diplopia on end-lateral gaze, no chemosis, no conjunctival injection, or inflammation of the caruncle, lids closed completely, proptosis with Hertel ophthalmometer measured 23 mm on the right eye and 22 mm in the left eye (normal range < 18 to 20 mm for Caucasians), thyroid not enlarged with no palpable nodules, no thyroid bruits. The initial Clinical Activity Score (CAS) was 4, which indicated active TED. A thyroid ultrasound showed Inhomogeneous echogenicity with increased vascularity consistent with autoimmune thyroiditis. An MRI of the orbits revealed diffuse extraocular muscle enhancement and enlargement with tendinous insertion sparing, increased T2 hyperintensity findings which favored thyroid eye disease. Further laboratory testing confirmed the presence of multiple thyroid autoantibodies: Thyrotropin binding inhibitory immunoglobulin 2.76 IU/L (normal range < 1.75 IU/L), Thyroid peroxidase antibody 1135 IU/mL (normal range <9 IU/mL), Thyroglobulin antibodies 157 IU/mL (normal range < 116 IU/mL), thyroid-stimulating immunoglobulin 447% (normal range <140 % Baseline). She was referred to ophthalmology for management of TED and was started on teprotumumab. Her CAS improved to 0 and her diplopia resolved. Her proptosis remained stable. This case illustrates an unusual clinical course in a patient who initially presented with autoimmune hypothyroidism, later developed Thyroid Eye Disease. A study by Kahaly GJ et al showed that in Hashimoto’s thyroiditis (HT), thyroid-stimulating autoantibodies are highly correlated with thyroid eye disease (TED) with positive thyroid-stimulating autoantibodies detected in 5.5% of the patients with HT and 68.2% in the patients with HT and TED. Even though it is less common, up to 6% of patients with HT may be affected by TED. Rare presentations such as this case emphasizes the need to be vigilant when evaluating eye symptoms in patients with autoimmune thyroid disease. Teprotumumab that showed improvement in patients with Grave’s and thyroid eye disease, was also successful in treating our patient symptoms. Presentation: 6/3/2024

Long-term Effect of Thyrotropin-binding Inhibitor Immunoglobulin on Atrial Fibrillation in Euthyroid Patients

ObjectiveIndividuals with hyperthyroidism are at an increased risk of atrial fibrillation (AF), but the association between autoantibodies and AF or cardiovascular mortality in individuals who have returned to normal thyroid function remains unclear. MethodsThe study utilized electronic medical records from National Taiwan University Hospital between 2000 and 2022. Each hyperthyroidism patient had at least 1 thyrotropin-binding inhibiting immunoglobulin (TBII) measurement. The relationship between TBII levels and the risk of AF and cardiovascular mortality was assessed using multivariable Cox regression models and Kaplan-Meier survival analysis. ResultsAmong the 14 618 enrolled patients over a 20-year timeframe, 173 individuals developed AF, while 46 experienced cardiovascular mortality. TBII values exceeding 35% were significantly associated with an elevated risk of AF for both the first TBII (hazard ratio {HR} 1.48 [1.05-2.08], P = .027) and mean TBII (HR 1.91 [1.37-2.65], P < .001). Furthermore, after free T4 levels had normalized, a borderline association between first TBII and AF (HR 1.59 [0.99-2.56], P = .056) was observed, while higher mean TBII increased AF (HR 1.78 [1.11-2.85], P = .017). Higher first and mean TBII burden continued to significantly impact the incidence of cardiovascular mortality (HR 6.73 [1.42-31.82], P = .016; 7.87 [1.66-37.20], P = .009). Kaplan-Meier analysis demonstrated that elevated TBII levels increased the risk of AF and cardiac mortality (log-rank P = .035 and .027, respectively). ConclusionIn euthyroid individuals following antithyroid treatment, elevated circulating TBII levels and burden are associated with an elevated risk of long-term incident AF and cardiovascular mortality. Further reduction of TBII level below 35% will benefit to clinical outcomes.

Comparison of two different TSH-receptor antibody assays: A clinical practice study

BackgroundGraves’ disease (GD) is caused by the production of TSH-receptor (TSHR) stimulating auto-antibodies. Over the years various TSHR-antibody (TRAb) detection assays have been developed. Most clinical laboratories use competitive TSH-binding inhibitory immunoglobulin (TBII) assays, which measure the total amount of stimulating and blocking auto-antibodies. Selective detection of TSHR stimulating auto-antibodies (TSI) was previously only possible with functional cell-based bioassays. However, more recently an automated bridge-based binding assay to more specifically measure TSI has become available. The aim of our study was to compare the third-generation automated competitive immunoassay (TBII) with the automated bridge immunoassay (TSI) in clinical practice in an academic thyroid expert center. MethodsA retrospective study in 356 patients with Graves’ disease, Graves orbitopathy (GO), and other (thyroid) disease treated in an academic thyroid center was performed. All samples were analyzed for TBII and TSI. For both assays, sensitivity, specificity, positive predictive value (PVV), negative predictive value (NPV) and diagnostic odds ratios were calculated using different cut-offs for negativity. ResultsUsing the provided cut-off, the overall sensitivity appeared similar between TBII and TSI, but TSI showed higher overall specificity, PPV, NPV and diagnostic odds ratio. Using two or three times the cut-off for negativity resulted in a decrease in sensitivity, but an increase in specificity and PPV, which was most pronounced for the TBII-assay. Analysis in a subgroup of newly diagnosed treatment naïve GD/GO patients also revealed overall favorable results for the TSI-assay. Increasing the cut-off for negativity resulted in increased specificity for both assays, with similar results using two or three times the cut-off. Most patients with concordant positive results for TBII and TSI suffered from GD or GD + GO (n = 110, 95.6 %), while patients negative for both TBII and TSI mostly suffered from other (thyroid) disease (n = 143, 77.3 %). From patients with positive TBII but negative TSI only 42.1 % had GD/GO (n = 16), whereas 57.9 % (n = 22) had other (thyroid) disease. In contrast, 88.9 % of patients with positive TSI but negative TBII had GD/GO (n = 16), whereas 11.1 % (n = 2) had other (thyroid) disease. ConclusionIn our academic thyroid center, the diagnostic performance of the TSI-assay outperformed the TBII-assay. Using a higher cut-off value for negativity can be helpful in assessing clinical relevance.

THU670 Serum TSI Concentration In Patients With Graves’ Disease Undergoing Maintenance-dose Of Antithyroid Drug (ATD) And Its Relationship With Disease Relapse After ATD Withdrawal

Abstract Disclosure: P.V. Nguyen: None. K.T. Nguyen: None. Background: Graves' disease (GD) is an autoimmune disorder in which thyroid-stimulating immunoglobulin (TSI) plays a key role in its pathogenesis. TSI assays have been recently optimized in their accuracy, and the procedure has also been simplified, which can potentially replace TRAb measured by conventional TSH-binding inhibitory immunoglobulins (TBII) assays in routine clinical practice. Objectives: Our objective was to study the serum TSI concentration in patients with Graves’ disease undergoing maintenance-dose ATD. We also aimed to assess the predictive value of TSI immunoassay, as well as the clinical signs and thyroid function tests in predicting Graves’ disease relapse following ATD discontinuation. Finally, follow-up would be continued to check for relapse or long term euthyroid status. Methods: Retrospective follow-up study of 352 patients with hyperthyroidism due to GD, treated at the endocrine outpatient clinic of Medic Medical Center, Ho Chi Minh City from January 2000 to April 2021. TSI was measured several times during the course of treatment when planning to stop the medication (at the discretion of the attending physician). ATD withdrawal would be considered when the patients achieved clinical euthyroidism with normal FT4 tests for at least 3 months with minimal dose of ATD. The decision to withdraw ATD was also based on TSI concentration, as well as the goiter’s characteristics and parenchymal vascularity observed via thyroid Doppler ultrasound. Results: The median TSI concentration of patients with GD undergoing maintenance-dose ATD was 1.45 IU/L (normal range &amp;lt;0.10 IU/L), and their thyroid function measured at the same time tended to be euthyroid in our study. TSI cut-off level at ATD withdrawal to predict the recurrence of GD was 1.31 IU/L which corresponded with the sensitivity, specificity, positive and negative predictive values of 63.64%, 78,79%, 50% and 86.67%, respectively. Multiple logistic regression analysis showed that the following factors were associated with an increased risk of relapse after the end of medical treatment: Graves' ophthalmopathy (GO), OR 3.69 (95% CI: 1.06-12.87; p=0.04), treatment duration less than 18 months, OR 7.77 (95% CI: 1.92-31.42; p&amp;lt;0.01), TSI level before ATD withdrawal ≥1.31 IU/L, OR 9.92 (95% CI: 2.77-35.42; p&amp;lt;0.01). Conclusion: At the time of ATD withdrawal, while normal FT4 levels were observed, high TSI levels were indicative of an ongoing immune process. These findings suggest that TSI measurements, in addition to clinical and ultrasound evaluations, may aid in the prediction of GD relapse after ATD discontinuation. In addition, GO, treatment duration of less than 18 months and TSI level before ATD withdrawal ≥1.31 IU/L were associated with an increased risk of relapse of GD after ATD discontinuation. Our study contributes to the expanding literature supporting the clinical utility of TSI assay in the management of GD. Presentation: Thursday, June 15, 2023

Relationship between Thyrotropin Binding Inhibitory Immunoglobulin and Strabismus-associated Thyroid Eye Disease Stability

Purpose: To investigate the relationship between thyrotropin binding inhibitory immunoglobulin (TBII) and deviation angle stability in strabismus-associated thyroid eye disease.Methods: A total of 25 strabismus-associated thyroid eye disease patients who were followed up for &gt; 6 months without surgery were enrolled. To investigate the correlation between TBII levels and changes in the deviation angle, a test period of 6 months from the date of TBII measurement was established and 55 test units of the corresponding TBII levels were obtained.Results: The deviation angle had a positive correlation with the TBII levels (r = 0.473, &lt;i&gt;p&lt;/i&gt; &lt; 0.001), but did not correlate with sex, age, and thyroid hormone levels. Changes in the horizontal, vertical, and total deviation angles were significantly greater in the high-TBII test units compared to the normal-TBII test units (&lt;i&gt;p&lt;/i&gt;= 0.029, = 0.032, and = 0.009, respectively).Conclusions: TBII levels were related to deviation angle stability in strabismus-associated thyroid eye disease. TBII may be a useful indicator for deviation angle stability in these patients over a period of 6 months.

The Early Changes in Thyroid-Stimulating Immunoglobulin Bioassay over Anti-Thyroid Drug Treatment Could Predict Prognosis of Graves' Disease.

To determine whether baseline thyroid-stimulating immunoglobulin (TSI) bioassay or its early response upon treatment with an anti-thyroid drug (ATD) can predict prognosis of Graves' disease (GD) in real-world practice. This retrospective study enrolled GD patients who had previous ATD treatment with TSI bioassay checked at baseline and at follow-up from April 2010 to November 2019 in one referral hospital. The study population were divided into two groups: patients who experienced relapse or continued ATD (relapse/persistence), and patients who experienced no relapse after ATD discontinuation (remission). The slope and area under the curve at 1st year (AUC1yr) of thyroid-stimulating hormone receptor antibodies including TSI bioassay and thyrotropin-binding inhibitory immunoglobulin (TBII) were calculated as differences between baseline and second values divided by time duration (year). Among enrolled 156 study subjects, 74 (47.4%) had relapse/persistence. Baseline TSI bioassay values did not show significant differences between the two groups. However, the relapse/persistence group showed less decremental TSI bioassay in response to ATD than the remission group (-84.7 [TSI slope, -198.2 to 8.2] vs. -120.1 [TSI slope, -204.4 to -45.9], P=0.026), whereas the TBII slope was not significantly different between the two groups. The relapse/persistence group showed higher AUC1yr of TSI bioassay and TBII in the 1st year during ATD treatment than the remission group (AUC1yr for TSI bioassay, P=0.0125; AUC1yr for TBII, P=0.001). Early changes in TSI bioassay can better predict prognosis of GD than TBII. Measurement of TSI bioassay at beginning and follow-up could help predict GD prognosis.

Interpretation of Thyroid Autoantibodies in Hyperthyroidism

Thyrotoxicosis is a clinical state with a variety of various etiologies that results from excess thyroid hormones, including hyperthyroidism and thyroiditis. Graves' disease (GD) is a well-known autoimmune thyroid disease that causes hyperthyroidism, and its pathogenesis is mainly driven by the thyroid-stimulating hormone receptor antibody (TSHRAb), which is highly specific for GD. Measuring the TSHRAb is a fast and accurate diagnostic tool for GD and has been used to monitor disease activity and the treatment response. However, conventional TSH-binding inhibitory immunoglobulin (TBII) does not differentiate between stimulating, blocking, or neutral antibodies. In contrast, thyroid stimulatory immunoglobulin bioassays differentiate between stimulating and blocking antibodies and have comparably high sensitivity and specificity to TBII for GD. We also discuss the role of thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) in thyrotoxicosis, although they are less specific than TSHRAb for GD. TPOAb is associated with autoimmune thyroiditis, while TgAb appears with TPOAb in patients with autoimmune thyroid disease. In addition, TPOAb or TgAb may be associated with a low recurrence of GD after discontinuing anti-thyroid drugs. Clinicians should interpret thyroid autoantibodies in the context of the patient's clinical presentation and consider their implications to manage and monitor thyrotoxicosis.

Incidence and risk factors for Graves' orbitopathy in patients who underwent anti-inflammatory and immunosuppressive treatment during medical treatment for Graves' disease: investigation of 1,553 cases with newly diagnosed Graves' disease and proposal of a predictive score.

Appropriate administration of anti-inflammatory and immunosuppressive treatment (AIIST) is important for patients with Graves' orbitopathy (GO). This study aimed to clarify the incidence and risk factors for GO treated with AIIST and propose a predictive score, among newly diagnosed Graves' disease (GD) patients in Japan. A total of 1,553 GD patients who were newly diagnosed during the year 2011 were investigated. AIIST included local and/or systemic glucocorticoid administration and retrobulbar irradiation. A multivariable Cox proportional hazards model was used to investigate the risk factors for GO underwent AIIST during medical treatment, including at diagnosis, of GD. Then, a GO score was created by summing each point assigned to risk factors based on their coefficient obtained in the Cox model. AIIST was administered to 107 patients (6.9%). The risk factors and hazard ratios for GO underwent AIIST were: age (per 10 years), 1.32 (95% confidence interval: 1.16-1.50), p < 0.0001; TSH binding inhibitory immunoglobulin (TBII) (per 10 IU/L), 1.33 (1.15-1.54), p = 0.0001; and thyroglobulin antibody (TgAb) negativity, 2.98 (1.96-4.59), p < 0.0001. The GO score, ranging from 0 to 8 points, showed moderate performance (area under the curve: 0.71, cut-off value: 5 points, sensitivity: 0.76, specificity: 0.59, positive predictive value: 0.12, negative predictive value: 0.97). AIIST was performed for patients with active manifestations of GO in 6.9% of newly diagnosed GD patients. The risk factors for GO underwent AIIST were higher age, higher TBII, and TgAb negativity. The GO score based on these factors may be useful in managing GO.

Predictive Model for Graves' Ophthalmopathy in Patients with New-Onset Graves' Disease.

Background: The most prevalent extrathyroidal manifestation of Graves' disease (GD) is Graves' ophthalmopathy (GO). However, only few methods allow for predictions of GO occurrence or progression in patients with GD. Methods: We retrospectively analyzed 1,074 patients with new-onset GD, and divided them into a derivation and a validation cohort based on the date of their GD diagnosis. We then separately analyzed clinical risk factors affecting the occurrence and progression of GO using multivariable regression analysis and created a predictive model based on the factors we identified as significant. Results: Of the 853 GD patients included in the derivation cohort, 101 (11.8%) developed GO. Those who developed GO were more likely to be smokers (25.7% vs. 8.5%, p < 0.001), were younger at the time of their GD diagnosis (35.0 years vs. 42.0 years, p < 0.001), more commonly had a family history of GD (27.7% vs. 17.2%, p = 0.015), and had higher thyrotropin-binding inhibitor immunoglobulin (TBII) levels at the time of their diagnosis (13.5 IU/L vs. 10.0 IU/L, p = 0.020) than those who did not develop GO. Of the 101 GO patients in the derivation cohort, after excluding 8 who initially had active and moderate-to-severe GO, 11 of the remaining 93 had progressed to more active or severe GO. GO patients with confirmed progression had a higher proportion of those older than 45 years (54.5% vs. 19.8%, p = 0.031), and they had a different initial clinical activity score distribution. The multivariable regression analysis identified age at GD diagnosis, sex, smoking history, family history of GD, total cholesterol level, and TBII level at the time of the diagnosis as significant risk factors of GO occurrence, and a predictive model including these risk factors was built to create a nomogram. Conclusions: The predictors of GO occurrence in patients with new-onset GD were female sex, positive smoking history, young age, family history of GD, high cholesterol level, and high TBII level. The predictive nomogram developed in this study may be useful in patient counseling and facilitating informed treatment decision-making.

Differential Diagnosis of Thyrotoxicosis by Machine Learning Models with Laboratory Findings.

Differential diagnosis of thyrotoxicosis is essential because therapeutic approaches differ based on disease etiology. We aimed to perform differential diagnosis of thyrotoxicosis using machine learning algorithms with initial laboratory findings. This is a retrospective study through medical records. Patients who visited a single hospital for thyrotoxicosis from June 2016 to December 2021 were enrolled. In total, 230 subjects were analyzed: 124 (52.6%) patients had Graves’ disease, 65 (28.3%) suffered from painless thyroiditis, and 41 (17.8%) were diagnosed with subacute thyroiditis. In consideration that results for the thyroid autoantibody test cannot be immediately confirmed, two different models were devised: Model 1 included triiodothyronine (T3), free thyroxine (FT4), T3 to FT4 ratio, erythrocyte sediment rate, and C-reactive protein (CRP); and Model 2 included all Model 1 variables as well as thyroid autoantibody test results, including thyrotropin binding inhibitory immunoglobulin (TBII), thyroid-stimulating immunoglobulin, anti-thyroid peroxidase antibody, and anti-thyroglobulin antibody (TgAb). Differential diagnosis accuracy was calculated using seven machine learning algorithms. In the initial blood test, Graves’ disease was characterized by increased thyroid hormone levels and subacute thyroiditis showing elevated inflammatory markers. The diagnostic accuracy of Model 1 was 65–70%, and Model 2 accuracy was 78–90%. The random forest model had the highest classification accuracy. The significant variables were CRP and T3 in Model 1 and TBII, CRP, and TgAb in Model 2. We suggest monitoring the initial T3 and CRP levels with subsequent confirmation of TBII and TgAb in the differential diagnosis of thyrotoxicosis.

Longitudinal association of thyroid-stimulating immunoglobulin levels with clinical characteristics in thyroid eye disease

ObjectivesThe clinical course of thyroid eye disease (TED) is heterogeneous and predicting patients who may develop the severe sequelae of the disease is difficult. In this study, we evaluated the...

Characterization of Apparently Paradoxical Thyrotropin Binding Inhibitory Immunoglobulins With Neutral Bioactivity.

ContextThe thyrotropin (TSH) receptor (TSH-R) autoantibody activity is clinically measured by inhibition of labeled ligand (TSH or M22) binding to the TSH-R (TSH-binding inhibitory immunoglobulin [TBII]) or by stimulation (TSH-R stimulating antibody [TSAb]) or inhibition (TSH-R blocking antibody [TSBAb]) of 3′,5′-cyclic adenosine 5′-monophosphate (cAMP) production in isolated cells.ObjectiveWe experienced a patient with hypothyroid Graves disease (GD) having strong positive TBII but with almost neutral bioactivities on the TSH-R. The aim of this study is the characterization of this apparently paradoxical TBII (serum sample S).MethodsWe first compared the TBII, TSAb, and TSBAb activities of serum sample S with mixtures of stimulating (S-mAb) and blocking monoclonal Ab (B-mAb). Next, we serially measured cAMPs stimulated by various serum samples in the presence or absence of TSH.ResultsMixtures of S-mAb and B-mAb did not reproduce the characteristics of serum sample S. Instead, serum sample S had a unique feature that blocked the TSH-stimulated cAMP initially but disappeared the blocking activity thereafter to reach the control level.ConclusionWe present here the TBIIs with neutral bioactivities found in the patient with autoimmune thyroid disease, which strongly inhibit TSH binding to the TSH-R but exerts neither TSAb nor TSBAb activity. Differences in the methods of detecting TRAb between TBII in vitro and bioassay may cause the discrepancy. Although serum sample S may be an extreme example, a variety of TRAb that not only stimulates or blocks but also interferes with TSH-R binding for only a short time may exist in the serum samples of GD patients.

Performance of Thyroid-Stimulating Immunoglobulin Bioassay and Thyrotropin-Binding Inhibitory Immunoglobulin Assay for the Diagnosis of Graves' Disease in Patients With Active Thyrotoxicosis

ObjectiveGraves' disease (GD) is caused by the stimulation of thyrotropin receptors by autoantibodies. We compared the diagnostic accuracy of the thyroid-stimulating immunoglobulin (TSI) bioassay and thyrotropin-binding inhibitory immunoglobulin (TBII) assay in differentiating GD from other causes of thyrotoxicosis. MethodsWe retrospectively evaluated 493 patients with thyrotoxicosis who were tested with the third-generation TSI and TBII assays simultaneously. Patients were classified according to the clinical, histopathologic, and imaging criteria into the following groups: positive reference group (PRG) (patients with GD), negative reference group (NRG) (patients without GD), and inconclusive group (patients without a definitive diagnosis). ResultsTSI and TBII assays were concordant in 88% of the cases and showed a strong positive correlation (rs = 0.844, P < .01). When analyzed collectively, TSI and TBII assays confirmed the diagnosis of GD in 79% of the PRG cases and excluded GD in 92.5% of patients in NRG. Combined TSI and TBII assays or TBII assay alone showed similar accuracy to the diagnosis of GD (81.4% and 77.5%, respectively). Tests in 40 of 191 patients in PRG were negative for both TSI and TBII assays, whereas 3 of 40 cases in NRG had at least 1 positive thyrotropin receptor antibody test. False-negative cases were associated with subclinical hyperthyroidism, normal radionuclide uptake, longer duration of thyrotoxicosis, and absence of goiter or Graves' ophthalmopathy. ConclusionTSI and TBII assays showed similar performance in differentiating GD from other causes of thyrotoxicosis in a real-world sample of patients with active thyrotoxicosis. In combination, both tests showed little benefit compared with the TBII assay alone. Thyrotropin receptor antibody assay results should be carefully interpreted in patients with mild GD or longstanding disease.

Long-term outcomes of Graves’ disease in children and adolescents receiving antithyroid drugs

PurposeAntithyroid drugs (ATDs) are primarily used as an initial treatment in pediatric patients with Graves’ disease (GD). We aimed to investigate the long-term outcomes in pediatric GD patients receiving ATDs.MethodsRetrospective data from a single center were collected from April 2003 to July 2020. A total of 98 children and adolescents aged 2–16 years diagnosed with GD and receiving ATDs was enrolled. We investigated the factors correlated with remission by comparing children who achieved remission after 5 years and those with persistent disease.ResultsThe study included 76 girls (77.6%) and 22 boys (22.4%). During the 5-year follow-up period, 18 children (18.3%) maintained remission, ATDs could not be discontinued in 74 patients (75.5%), and relapse occurred in 6 patients (6.2%). The remission group had significantly lower thyroid-stimulating hormone-binding inhibitory immunoglobulin (TBII) level at diagnosis (P=0.002) and 3 months (P=0.002), 1 year (P=0.002), 2 years (P≤0.001), 3 years (P≤0.001), 4 years (P≤0.001), and 5 years (P≤0.001) after ATD treatment than did the nonremission group. The remission group also had a shorter time for TBII normalization after ATD treatment (P≤0.001). Multiple logistic regression analysis showed that the time to TBII normalization (cutoff time=2.35 years) was related to GD remission (odds ratio, 0.596; 95% confidence interval, 0.374–0.951).ConclusionsTBII level and time to TBII normalization after ATD treatment can be used to predict remission in pediatric GD patients.

Changes in Thyrotropin Receptor Antibody Levels Following Total Thyroidectomy or Radioiodine Therapy in Patients with Refractory Graves' Disease.

Background: The actions of thyrotropin-binding inhibitory immunoglobulins (TBIIs) against thyrotropin receptors in thyroid follicular cells have been studied as important etiological factors in Graves' disease (GD). The purpose of this study was to investigate changes in the TBII levels of patients undergoing total thyroidectomy (TTx) or radioactive iodine (RAI) therapy for GD refractory to antithyroid drugs (ATDs).Methods: We enrolled patients who underwent TTx or RAI for GD with previous ATD use between January 2011 and December 2017 at the Samsung Medical Center in Seoul, Korea. Thorough retrospective reviews of medical records were performed in 130 patients.Results: Patients with goiter, ophthalmopathy, high levels of TBIIs, and high doses of ATDs received TTx. Elderly patients with arrhythmia received RAI. We observed that TBII levels continued to decrease after TTx. On the contrary, TBIIs initially increased for 138 days (estimated median time) and then decreased slowly after RAI. A faster decline in TBII levels was observed in the TTx group than in the RAI group (p < 0.001). The estimated median time for TBIIs to decrease below 4.5 IU (3 × upper normal limit, which is known to be a risk factor for fetal hyperthyroidism) was 318 days in the TTx group and 659 days in the RAI group, respectively. In the RAI group, high levels of TBII (>4.5 IU/L) were present in 70 (82%) at 6 months, 57 (67%) at 1 year, and 3 (3%) at 2 years. In the TTx group, rapid decreases in TBII levels were observed in younger patients and those with lower baseline TBII levels. In the RAI group, smaller thyroid volume was correlated with more rapid decrease in TBII levels.Conclusions: The changes in TBII levels following TTx or RAI were different in patients with refractory GD. When deciding on TTx or RAI, this difference should be considered with patient age, severity of hyperthyroidism, goiter, ophthalmopathy, and future pregnancy plans (for young female patients).

Role of Proprotein Convertase Subtilisin/Kexin Type 9 in the Pathogenesis of Graves' Orbitopathy in Orbital Fibroblasts.

BackgroundThe proprotein convertase subtilisin/kexin type 9 (PCSK9) has been implicated in the pathogenesis of inflammatory diseases. We sought to investigate the role of PCSK9 in the pathogenesis of Graves’ orbitopathy (GO) and whether it may be a legitimate target for treatment.MethodsThe PCSK9 was compared between GO (n=11) and normal subjects (n=7) in orbital tissue explants using quantitative real-time PCR, and in cultured interleukin-1β (IL-1β)-treated fibroblasts using western blot. Western blot was used to identify the effects of PCSK9 inhibition on IL-1β-induced pro-inflammatory cytokines production and signaling molecules expression as well as levels of adipogenic markers and oxidative stress-related proteins. Adipogenic differentiation was identified using Oil Red O staining. The plasma PCSK9 concentrations were compared between patients with GO (n=44) and healthy subjects (n=26) by ELISA.ResultsThe PCSK9 transcript level was higher in GO tissues. The depletion of PCSK9 blunted IL-1β-induced expression of intercellular adhesion molecule 1 (ICAM-1), IL-6, IL-8, and cyclooxygenase-2 (COX-2) in GO and non-GO fibroblasts. The levels of activated nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and phosphorylated forms of Akt and p38 were diminished when PCSK9 was suppressed in GO fibroblasts. Decreases in lipid droplets and attenuated levels of peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein β (C/EBPβ), and leptin as well as hypoxia-inducible factor 1α (HIF-1α), manganese superoxide dismutase (MnSOD), thioredoxin (Trx), and heme oxygenase-1 (HO-1) were noted when PCSK9 was suppressed during adipocyte differentiation. The plasma PCSK9 level was significantly higher in GO patients and correlated with level of thyrotropin binding inhibitory immunoglobulin (TBII) and the clinical activity score (CAS).ConclusionsPCSK9 plays a significant role in GO. The PCSK9 inhibition attenuated the pro-inflammatory cytokines production, oxidative stress, and fibroblast differentiation into adipocytes. PCSK9 may serve as a therapeutic target and biomarker for GO.

THYROTROPIN-RECEPTOR ANTIBODIES, IMMUNOGLOBULIN E AND ANTINUCLEAR ANTIBODIES IN PATIENTS WITH GRAVES' DISEASE AND GRAVES' ORBITOPATHY.

Thyrotropin-receptor antibodies (TRAb) are biomarkers of Graves' disease (GD) and Graves' orbitopathy (GO). Elevated immunoglobulin E (IgE) and antinuclear antibodies (ANA) were also found in GD patients. We aimed to assess TRAb, IgE and ANA in GD and GO patients and to evaluate the relationship between the immunological markers and smoking. This was a comparative cross-sectional study carried out in a single tertiary care center from June 2018 to January 2020. A total of 103 GD patients (mean age 51.2, 84 females) were divided into three subgroups: moderate-to-severe GO (n=36), mild GO (n=32) and "only GD" subgroup (n=35). Forty healthy controls (HC) (mean age 51.2, 36 females) were also included. TRAb were measured by a thyrotropin-binding inhibitory immunoglobulin (TBII) assay in GD patients; IgE and ANA - by an enzyme-linked immunosorbent assay in all subjects. GD patients had higher IgE-positivity rate (p=0.04) and similar ANA-positivity compared to HC. Moderate-to-severe GO subgroup had the highest TBII (p<0.01), the lowest TBII-negativity rate (p<0.01) and the highest ANA-positivity rate (p=0.03) and was the only subgroup whose IgE-positivity rate was significantly higher than HC (25% vs. 7.5%). Mild GO and "only GD" patients had comparable TBII, TBII-negativity rate, IgE and ANA.Both GO subgroups had significantly higher smoking rate than "only GD" patients. Smoking was positively associated with IgE positivity (φ=0.22, p=0.03), and negatively with TBII negativity rate (φ=-0.24, p=0.02). GD patients exhibit different immunological patterns depending on the presence and severity of GO. Smoking might be just one of the factors responsible for the clinical and immunological variety of GD. Further studies are needed.

Antithyroid drugs in Graves' hyperthyroidism: differences between "block and replace" and "titration" regimes in frequency of euthyroidism and Graves' orbitopathy during treatment.

Whereas antithyroid drugs (ATD) are the preferred treatment modality for Graves' hyperthyroidism (GH), there is still controversy about the optimal regimen for delivering ATD. To evaluate whether 'Block and Replace' (B + R) and 'Titration' (T) regimes are equivalent in terms of frequency of euthyroidism and Graves' Orbitopathy (GO) during ATD therapy. A prospective multicentre observational cohort study of 344 patients with GH but no GO at baseline. Patients were treated with ATD for 18months according to B + R or T regimen in line with their institution's policy. Baseline characteristics were similar in both groups. In the treatment period between 6 and 18months thyrotropin (TSH) slightly increased in both groups, but TSH was on average 0.59mU/L (95% CI 0.27-0.85) lower in the B + R group at all time points (p = 0.026). Serum free thyroxine (FT4) remained stable during the same interval, with a tendency to higher values in the B + R group. The point-prevalence of euthyroidism (TSH and FT4 within their reference ranges) increased with longer duration of ATD in both groups; it was always higher in the T group than in the B + R group: 48 and 24%, respectively, at 6months, 81 and 58% at 12months, and 87 and 63% at 18months (p < 0.002). There were no significant differences between the B + R and T regimens with respect to the fall in thyrotropin binding inhibiting immunoglobulins (TBII) or thyroid peroxidase antibodies (TPO-Ab). GO developed in 15.9% of all patients: 9.1 and 17.8% in B + R group and T group, respectively, (p = 0.096). GO was mild in 13% and moderate-to-severe in 2%. The prevalence of biochemical euthyroidism during treatment with antithyroid drugs is higher during T compared to B + R regimen. De novo development of GO did not differ significantly between the two regimens, although it tended to be higher in the T group. Whether one regimen is clinically more advantageous than the other remains unclear.