Clinical value of functional thyrotropin receptor antibodies in Serbian patients with Graves' orbitopathy.

PURPOSE: Thyrotropin receptor autoantibodies (TSH-R-Ab) are heterogeneous in their biological function and play a significant role in the pathophysiology of both Graves' disease and Graves' orbitopathy (GO). The clinical significance and utility of determining functional TSH-R-Ab in a Serbian collective were evaluated. METHODS: 91 consecutive patients with GO were included in this study. Total TSH-R-Ab concentration, referred to as TSH-R binding inhibitory immunoglobulins (TBII) was detected using a competitive-binding immunoassay. Stimulating and blocking TSH-R-Ab (TSAb and TBAb) were measured with cell-based bioassays. RESULTS: Stimulating TSAb activity and TBII positivity were detected in 85 of 91 (93.4%) and 65 of 91 (71.4%) patients with GO (P < 0.001). Blocking TBAb activity was observed in only one patient who expressed dual stimulating and blocking TSH-R-Ab activity. The sensitivity rates for differentiating between clinically active versus inactive and mild versus moderate-to-severe GO were 100% and 100% for TSAb, respectively. In contrast, these were 82% and 87% only for TBII. Seven of eight (87.5%) and one of eight (12.5%) euthyroid patients with GO were TSAb and TBII positive, respectively (P < 0.031). TSAb serum levels significantly predicted GO activity compared to TBII (odds ratio, OR, 95%CI: 3.908, 95%CI 1.615-9.457, P = 0.003; versus 2.133, 0.904-5.032, P = 0.084, univariate analysis; and OR 4.341, 95%CI 1.609-11.707, P = 0.004; versus 2.337, 0.889-6.145, P = 0.085 multivariate analysis). CONCLUSION: Stimulating TSAb are highly prevalent in patients with GO and show superior clinical characteristics and predictive potential compared to the traditionally used TBII.

Diagnostic accuracy of Immulite® TSI immunoassay for thyroid-associated orbitopathy in patients with recently diagnosed Graves' hyperthyroidism.

PURPOSE: The Immulite® thyroid stimulating immunoglobulin (TSI) immunoassay is a relatively new commercial assay that has shown good diagnostic accuracy in Graves' hyperthyroidism (GH). However, its clinical utility in thyroid-associated orbitopathy (TAO) is less clear. The purpose of this study was to assess the diagnostic accuracy of the Immulite® TSI immunoassay for TAO and investigate the associations between TSI and other clinical measures. METHODS: One hundred and forty patients that had been diagnosed with GH within the previous 12 months were recruited. Identification and grading of TAO were performed at enrolment and serum samples were analysed using the Immulite® TSI immunoassay. RESULTS: Of the 140 participants recruited, 75 (53.6%) had TAO. Age, sex and time since GH diagnosis were similar between those with and without TAO (p ≥ 0.300). TSI level tended to decrease with increasing time from GH diagnosis (Spearman's ρ - 0.28, 95% CI - 0.43, - 0.12). TSI levels were higher among those with than those without TAO (median 4.0 vs. 2.7 IU/L, respectively, p = 0.037). There was no correlation between TSI level and inflammatory index score (ρ = 0.14, 95% CI - 0.03, 0.30) or clinical severity (p = 0.527) among those with TAO. TSI level showed poor diagnostic accuracy for TAO (area under the receiver operating characteristic curve 0.60, 95% CI 0.51, 0.70). CONCLUSIONS: Although Immulite® TSI level was higher in the presence of TAO, it showed poor diagnostic accuracy and no correlation with clinical markers of TAO severity or activity.

The Impact of Interferon Beta-1b Therapy on Thyroid Function and Autoimmunity Among COVID-19 Survivors.

Background: Some studies have indicated that interferon (IFN) may be valuable in COVID-19. We aimed to evaluate the impact of short-term IFN on incident thyroid dysfunction and autoimmunity among COVID-19 survivors. Methods: We included consecutive adults without known thyroid disorder admitted to Queen Mary Hospital for COVID-19 from July 2020 to January 2021 who had thyroid function tests (TFTs) and anti-thyroid antibodies measured both on admission and at three months. Results: 226 patients were included (median age 55.0 years; 49.6% men): 135 were IFN-treated. There tended to be more abnormal TFTs upon reassessment in IFN-treated patients (8.1% vs 2.2%, p=0.080). 179 patients (65.4% IFN-treated) had a complete reassessment of anti-thyroid antibodies. There were significant increases in titres of both anti-thyroid peroxidase antibodies (anti-TPO: baseline 29.21 units [IQR: 14.97 - 67.14] vs reassessment 34.30 units [IQR: 18.82 - 94.65], p<0.001) and anti-thyroglobulin antibodies (anti-Tg: baseline 8.23 units [IQR: 5.40 - 18.44] vs reassessment 9.14 units [IQR: 6.83 - 17.17], p=0.001) in the IFN-treated group but not IFN-naïve group. IFN treatment (standardised beta 0.245, p=0.001) was independently associated with changes in anti-TPO titre. Of the 143 patients negative for anti-TPO at baseline, 8 became anti-TPO positive upon reassessment (seven IFN-treated; one IFN-naïve). Incident anti-TPO positivity was more likely to be associated with abnormal TFTs upon reassessment (phi 0.188, p=0.025). Conclusion: IFN for COVID-19 was associated with modest increases in anti-thyroid antibody titres, and a trend of more incident anti-TPO positivity and abnormal TFTs during convalescence. Our findings suggest that clinicians monitor the thyroid function and anti-thyroid antibodies among IFN-treated COVID-19 survivors, and call for further follow-up studies regarding the clinical significance of these changes.

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).

Management of thyrotoxicosis during pregnancy.

Thyrotoxicosis during pregnancy should be adequately managed and controlled to prevent maternal and fetal complications. The evaluation of thyroid function in pregnant women is challenged by the physiological adaptations associated with pregnancy, and the treatment with antithyroid drugs (ATD) raises concerns for the pregnant woman and the fetus. Thyrotoxicosis in pregnant women is mainly of autoimmune origin, and the measurement of thyroid stimulating hormone-receptor antibodies (TRAb) plays a key role. TRAb helps to distinguish the hyperthyroidism of Graves' disease from gestational hyperthyroidism in early pregnancy, and to evaluate the risk of fetal and neonatal hyperthyroidism in late pregnancy. Furthermore, the measurement of TRAb in early pregnancy is recommended to evaluate the need for ATD during the teratogenic period of pregnancy. Observational studies have raised concern about the risk of birth defects associated with the use of ATD in early pregnancy and challenged the clinical management and choice of treatment.

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.

Role of a new bioassay for thyroid-stimulating antibodies (aequorin TSAb) in Graves' ophthalmopathy.

Graves' ophthalmopathy (GO) is characterized by an autoimmune reaction against thyrotropin (TSH) receptors and is diagnosed by TSH receptor antibody (TRAb). A novel assay for thyroid-stimulating antibody (TSAb) was recently introduced using a frozen Chinese hamster ovary cell line expressing TSH receptors, cyclic adenosine monophosphate (cAMP)-gated calcium channel, and aequorin (aequorin TSAb). The aim of this study was to evaluate the role of aequorin TSAb in GO. We studied 136 Japanese patients with GO (22 euthyroid and 8 hypothyroid GO patients) at our hospital. TRAbs were estimated by first generation TRAb (TRAb 1st), second generation TRAb (hTRAb 2nd), conventional porcine TSAb, and the new aequorin TSAb assays. Aequorin TSAb, porcine TSAb, TRAb 1st, and hTRAb 2nd were positive in 125/136 (92%), 110/136 (81%), 81/130 (62%), and 93/114 (82%) patients, respectively. In patients with hyperthyroid GO, they were positive in 98/106 (98%), 96/106 (91%), 78/101 (77%), and 84/93 (90%) patients, respectively. In patients with euthyroid GO, they were positive in 19/22 (86%), 9/22 (41%), 1/21 (5%), and 6/17 (35%) patients, respectively. Aequorin TSAb levels were significantly related to TRAb 1st (r = 0.4172, p < 0.0001), hTRAb 2nd (r = 0.2592, p < 0.0001), and porcine TSAb (r = 0.4665, p < 0.0001). Clinical activity score (CAS) was significantly greater in patients with high titers of aequorin TSAb than in those with low titers. Aequorin TSAb levels were significantly related to the signal intensity ratio of the enlarged eye muscle and proptosis evaluated by MRI before steroid pulse therapy. Aequorin TSAb assay was more sensitive than the conventional assays, especially in euthyroid GO.

Analytical and clinical performance of newly developed immunoassay for detecting thyroid-stimulating immunoglobulin, the Immulite TSI assay.

Graves' disease (GD) is caused by autoantibodies against the thyrotropin receptor (TRAb), and among the three types of TRAbs, only the stimulating type (TSI) is known to be associated with GD. In this study, we evaluated the analytical performance of a new fully automated chemiluminescent TSI immunoassay, namely, the Immulite TSI assay, and compared the diagnostic efficacy of the assay with the Elecsys Anti-TSH receptor (TSHR) assay. Precision was evaluated using two levels of quality control reagents, and linearity was evaluated across the expected analytical measurement range (0.18-37.35 IU/L) at five levels using clinical samples. A comparative evaluation between the two assays was performed using 187 clinical samples, and the concordance of qualitative results was also assessed. The repeatability and total imprecision (% coefficient of variation) of the Immulite TSI assay were 3.19% and 3.46% at 0.93 IU/L, and 3.76% and 5.42% at 19.3 IU/L, respectively. The linearity of this assay ranged from 0.16 to 6.17 IU/L. A high degree of correlation was observed between quantitative values from each assay (correlation coefficient = 0.819). Moderate agreement between methods was observed with an overall qualitative agreement of 93.0%. Among 13 cases with discordant qualitative results, the Immulite TSI assay generated more favorable results consistent with clinical diagnoses of patients than the Elecsys Anti-TSHR assay. The Immulite TSI assay showed reliable analytical performance and good correlation with the Elecsys Anti-TSHR assay and we expect this method will be helpful for clinicians to evaluate patients with hyperthyroidism.

Prognostic value of change in anti-thyroglobulin antibodies after thyroidectomy in patients with papillary thyroid carcinoma

Purpose: Anti-thyroglobulin antibodies (TgAb) can be used as a surrogate tumor marker in the follow-up of papillary thyroid carcinoma (PTC). We try to determine if the change in TgAb levels in the first post-operative year is a good predictor of persistence/recurrence risk in TgAb-positive PTC patients. Methods/patients: 105 patients with PTC who underwent thyroidectomy between 1988 and 2014 were enrolled. We calculated the percentage of change in TgAb levels with the first measurement at 1-2 months after surgery and the second one at 12-14 months. Results: TgAb negativization was observed in 29 patients (27.6%), a decrease of more than 50% was observed in 57 patients (54.3%), less than 50% in 12 patients (11.4%) and in 7 patients (6.7%) the TgAb level had increased. The percentage of persistence/recurrence was 0, 8.8, 16.7 and 71.4% in each group, respectively (p < 0.001). In the multivariate analysis, only the percentage of change in TgAb showed a significant association with the risk of persistence/recurrence, regardless of other factors such as age, size and TNM stages. Conclusions: Changes in TgAb levels in the first year after surgery can predict the risk of persistence/recurrence of TgAb-positive PTC patients. Patients who achieved negativization of TgAb presented an excellent prognosis

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Gestante eutiroidea con anticuerpos estimulantes del receptor de tirotropina positivos: manifestación tardía de hipertiroidismo neonatal. A propósito de un caso / Euthyroid pregnant woman with positive thyrotropin receptor-stimulating antibodies: Late manifestation of neonatal hyperthyroidism. About a case

Las enfermedades tiroideas, después de la diabetes mellitus, se encuentran entre los trastornos endocrinos más comunes durante el embarazo, con una incidencia del 5-10%. Es importante su detección y tratamiento precoz ya que puede tener consecuencias negativas tanto para la madre como para el feto. El hipertiroidismo se encuentra en menor frecuencia que el hipotiroidismo durante el embarazo, entre 0,1-1%. Se caracteriza por presentar tirotropina baja con hormonas tiroideas elevadas, siendo la enfermedad de Graves la causa más frecuente (el 85% de los casos). A continuación se expone el caso de un lactante con hipertiroidismo primario de etiología autoinmune, hijo de una madre sin diagnóstico previo de hipertiroidismo durante la gestación (AU)

Thyroid diseases, after diabetes mellitus, are among the most common endocrine disorders during pregnancy, with an incidence of 5-10%. Early detection and treatment is important, as they can have negative consequences for both the mother and the foetus. Hyperthyroidism is less frequent than hypothyroidism during pregnancy, being between 0.1% and 1%. It is characterised by a low thyrotropin with elevated thyroid hormones, with Graves’ disease being the most frequent cause (85% of cases). The following is the case of an infant with primary hyperthyroidism of autoimmune origin, the son of a mother without previous diagnosis of hyperthyroidism during gestation (AU)

PREDICTION OF RELAPSE FROM HYPERTHYROIDISM FOLLOWING ANTITHYROID MEDICATION WITHDRAWAL USING TECHNETIUM THYROID UPTAKE SCANNING.

OBJECTIVE: Technetium thyroid uptake (TTU) is not inhibited by antithyroid drugs (ATD) and reflects the degree of thyroid stimulation. We intended to predict the relapse rate from hyperthyroidism based on TTU measurement. METHODS: Out of 44 initially enrolled subjects, 38 patients aged 41.6 ± 14.6 with Graves disease (duration: 84 ± 78 months) completed the study. TTU was performed with 40-second imaging of the neck and mediastinum 20 minutes after injection of 1 mCi technetium-99m pertechnetate. TTU was measured as the percentage of the count of activity accumulated in the thyroidal region minus the mediastinal background uptake to the count of 1 mCi technetium-99m under the same acquisition conditions. Then methimazole was stopped and patients were followed. The optimal TTU cutoff value for Graves relapse prediction was calculated using Youden's J statistic. RESULTS: Hyperthyroidism relapsed in 11 (28.9%) patients 122 ± 96 (range: 15-290) days post-ATD withdrawal. The subjects in remission were followed for 209 ± 81 days (range: 88-390). TTU was significantly higher in patients with forthcoming relapse (12.0 ± 8.0 vs. 3.9 ± 2.0, P = .007). The difference was significant after adjustment for age, sex, history of previous relapse, disease duration, and thyroid-stimulating hormone (TSH) levels before withdrawal. The area under the receiver operative characteristic (ROC) curve was 0.87. The optimal TTU cutoff value for classification of subjects with relapse and remission was 8.7 with sensitivity, specificity, and positive and negative predictive value of 73%, 100%, 100%, and 90%, respectively (odds ratio [OR] = 10.0; 95% confidence interval [CI]: 3.4-29.3). CONCLUSION: TTU evaluation in hyperthyroid patients receiving antithyroid medication is an accurate and practical method for predicting relapse after ATD withdrawal. ABBREVIATIONS: ATD = antithyroid drugs RIU = radio-iodine uptake TSH = thyroid-stimulating hormone TSI = thyroid-stimulating immunoglobulin TTU = technetium thyroid uptake.

Measuring TSH receptor antibody to influence treatment choices in Graves' disease.

TSH receptor antibody (TRAb) plays a key role in the pathogenesis of Graves' disease (GD), and its levels correlate with the clinical course. The second- and third-generation TRAb assays have >95% sensitivity and specificity for the diagnosis of GD and have improved the utility of TRAb to predict relapse. TRAb levels decline with antithyroid drug (ATD) therapy and after thyroidectomy. Its level increases for a year following radioactive iodine (RAI) therapy, with a gradual fall thereafter. TRAb level >12 IU/l at diagnosis of GD is associated with 60% risk of relapse at 2 years and 84% at 4 years. The prediction of risk of relapse improves further to >90% with TRAb >7·5 IU/l at 12 months or >3·85 IU/l at cessation of ATD therapy. TRAb tests are not expensive, and hence, TRAb measurements at presentation, after 12 months and/or 18 months (at cessation) of ATD therapy, could potentially guide treatment choices in GD. Elevated TRAb favours definitive treatment in the form of RAI or thyroidectomy, depending on the presence or absence of moderate-to-severe Graves' ophthalmopathy (GO) and the ability to comply with radiation protection requirements. Use of ATDs in early pregnancy is associated with increased risk of congenital anomalies; early ablative treatment (RAI/surgery) should be considered in women of childbearing age at higher risk of relapse of GD. TRAb ≥5 IU/l in pregnant women with current or previously treated GD is associated with increased risk of foetal and neonatal thyrotoxicosis, and hence needs close monitoring. TRAb levels parallel the course of GO, and elevated TRAb is an indication for steroid prophylaxis to prevent progression of GO with RAI therapy.

Partial prediction of postpartum Graves' thyrotoxicosis by sensitive bioassay for thyroid-stimulating antibody measured in early pregnancy.

Graves' disease often occurs after delivery. However, it has been difficult to predict who will develop Graves' hyperthyroidism. We attempted to predict postpartum onset of Graves' disease by measuring anti-TSH receptor antibodies (TRAb) and thyroid-stimulating antibodies (TSAb) in early pregnancy. TRAb was measured by a third generation assay and TSAb was measured by a newly developed sensitive bioassay. In 690 early pregnant women, 2 showed borderline TRAb positive reactions. However, none of them developed Graves' disease after delivery. Thirty-eight of 690 pregnant women were positive for anti-thyroid peroxidase antibodies (TPOAb) and 4 were positive for TSAb. Two of these 4 women developed postpartum Graves' hyperthyroidism. These findings indicate that the third generation TRAb assay was not useful, but that the sensitive TSAb bioassay was moderately useful for predicting the postpartum onset of Graves' hyperthyroidism.

Analytical Performance and Validation of a Bioassay for Thyroid-Blocking Antibodies.

BACKGROUND AND OBJECTIVE: A cell-based bioassay for the measurement of thyroid blocking autoantibodies (TBAb) has been recently reported. The analytical performance and validation of this bioassay is assessed and described. METHODS: Chinese hamster ovary cells expressing a chimeric thyrotropin receptor were treated with bovine (b) TSH and different concentrations of an immunoglobulin G (IgG) monoclonal human TBAb (K1-70). TBAb was measured as a function of luciferase activity relative to bTSH alone and expressed as percent inhibition. Results obtained in the chimeric cell line were compared with those of a wild-type cell line. Analytical performance studies were subsequently performed with the chimeric cell line only. RESULTS: Immunodepletion of K1-70 IgG by using a protein G-Sepharose column showed that positive percent inhibition in the TBAb bioassay was detectable from K1-70 IgG only. The limit of blank was determined to be 12.2%. The limit of detection was 14% inhibition, equivalent to 0.4 ng/mL K1-70, while the limit of quantitation was 22% (coefficient of variation [CV] 12%) equivalent to 0.625 ng/mL K1-70. The dynamic range was between 14 ± 3.7 (mean % inhibition ± standard deviation) and 101 ± 2.6, equivalent to 0.4-10 ng/mL K1-70. The linear range was between 22 ± 2.6 and 93 ± 0.6 inhibition, equivalent to 0.625-5 ng/mL K1-70. The upper limit of the 99th percent reference range was 34% inhibition. In two laboratories, CV values for the intra- and inter-assay precisions for K1-70 ranged from 2% to 12% and from 1.7% to 14.5%, respectively. For patient sera, the CV values for the intra- and inter-assay precisions ranged from 3% to 9% and from 3% to 11%, respectively. No interference was found when follicle-stimulating hormone, luteinizing hormone, and human chorionic gonadotrophin were tested in the TBAb bioassay. The median of % inhibition values in 40 TBAb positive sera from patients with autoimmune thyroid disease were 93.5 (range 25-103) and 92 (range 64-107) for the wild type and chimeric cell lines, respectively. Further, all 40 samples of patients with various non-thyroidal autoimmune diseases were TBAb negative. CONCLUSIONS: This TBAb bioassay exhibits excellent analytical performance and high level of reproducibility.

TSH receptor antibody titers measured with a third-generation assay did not reflect the activity of Graves' ophthalmopathy in untreated Japanese Graves' disease patients.

TSH receptor antibody (TRAb) titer has been reported to be correlated with Graves' ophthalmopathy (GO). However, the correlation between GO activity and TRAb titer assessed with a third-generation assay has not been reported. We enrolled 238 untreated Graves' disease patients who came to the outpatient clinic of Ito Hospital and 28 patients who were euthyroid. All of the patients were assessed for GO by an ophthalmologist within 3 months of their initial visit to Ito Hospital. Clinical activity score (CAS), short inversion time inversion recovery (STIR), and sum of the maximum external orbital muscle areas (SEOMA) on a frontal sectional magnetic resonance imaging (MRI). The TRAb titer was significantly higher in patients with inactive ophthalmopathy (the inactive-GO group) than in patients with active ophthalmopathy (the active-GO group) (17.7 ± 13.5 IU/L vs. 13.0 ± 13.1 IU/L, p=0.0082). The SEOMA values were not correlated with TRAb titer. The prevalence of active-GO was higher in euthyroid patients than in hyperthyroid patients although the difference was not significant. In conclusion, TRAb titer measured with a third-generation assay dose not correlate with GO activity based on MRI findings in untreated Graves' disease patients, and the prevalence of active-GO is higher in euthyroid patients with lower TRAb titers than in hyperthyroid patients.

A novel method for measuring TBAb activity in TSAb- and TBAb-positive serum.

We reported a conversion assay in which thyroid blocking antibody (TBAb) function as thyroid stimulating antibody (TSAb). TBAb-bound porcine thyroid cells (PTC) were made by incubating TBAb(+) serum and PTC for 1 hour. When these TBAb-bound PTC were incubated 4 h with rabbit anti-human (h) IgG antibody (Ab), cAMP production was high, but when incubated with normal rabbit serum (NRS) cAMP production was low. TBAb-Mnoclonal Ab (MoAb) (KI-70) showed similar conversion. However, when TSAb-MoAb(M22) was assayed, anti-hIgG Ab-produced cAMP was lower than NRS-produced cAMP. When a mixture of M22 and KI-70 was assayed, anti-hIgG Ab-produced cAMP was higher than NRS. Thus, it is possible to determine existence of TBAb in TSAb(+)serum when anti-IgG Ab-produced cAMP is higher than NRS-produced cAMP. In this assay TBAb activity in TSAb(+)serum was scored as positive, gray zone and negative when the difference [anti-hIgG Ab-produced cAMP(%)-NRS-produced cAMP(%)] was >100%, 50-100% and <±50%, respectively. In TSAb(+)sera of Graves' patients with no treatment or anti-thyroid therapy, positive TBAb was 9% (3/33 )and 6.9% (5/72), and gray zone was 18 % (6/33) and 25% (18/72), respectively. A low prevelance of TBAb and low TBAb activity (<200% as cAMP) was found in these Graves' patients. A radioisotope treated Graves' patient showed existence of both TSAb and TBAb at 5 months (NRS, 800% cAMP and anti-IgGAb,1,350% cAMP), and highly positive TBAb (NRS, 180% cAMP and anti-hIgG Ab, 3,200% cAMP) at 30 months. This conversion assay is useful principally for TBAb determination but is also useful for TBAb determination in TSAb(+)serum.

[TSH-receptor antibodies: immunoanalytical characteristics]. / Les anticorps anti-récepteur de la TSH : caractéristiques immunoanalytiques.

Besides the main biochemical characteristics of anti TSH-receptor antibodies, this paper points out the optimal conditions for their assays and the interpretation of results.

Standardization of a bioassay for thyrotropin receptor stimulating autoantibodies.

BACKGROUND: Cell-based bioassays for functional thyroid stimulating autoantibodies (TSAb) are sensitive diagnostic tools. However, there is no bioassay available that is standardized with international reference material. We aimed to promote the standardization of the test results among laboratories that perform TSAb bioassays and calibrate TSAb levels against the second international standard (IS) 08/204 from the National Institute for Biological Standards and Control (NIBSC). METHODS: Serum TSAb activity was measured with a FDA-cleared bioassay that utilizes CHO cells expressing a chimeric thyrotropin receptor (TSHR) and a c-AMP response-element-dependent luciferase. The IS was applied for calibration. TSAb results were reported as percentage of specimen-to-reference ratio (SRR%) and converted into mIU/L. RESULTS: The IS dose-response curve was obtained using concentrations from 0.3125 to 200 mIU/L. Mean TSAb SRR%±standard deviation (SD) values for the IS concentrations 0.3125, 0.625, 1.25, 2.5, 5, 10, 20, 40, 60, 80, 100, 120, 160, and 200 mIU/L were 63±4 (CV 6.3%), 63±4 (6.3), 67±2 (3.0), 76±6 (7.9), 91±8 (8), 134±8 (5.9), 201±13 (6.5), 294±12 (4.1), 336±10 (3.0), 348±8 (2.3), 360±14 (3.8), 371±15 (4.0), 381±9 (2.4), and 389±10 (2.6), respectively. A total of 127 dilution experiments were performed using 12 high TSAb-positive sera from patients with Graves' disease. When diluting TSAb-positive sera, IS concentrations within the linear range 5, 10, 20, 40, and 80 mIU/L were used for the calibration curve. All standard curves had R(2) values >0.95. Low coefficient of variation (CV %) values for the IS calibration curve (4-6%) were obtained. Compared to bovine TSH, no significant differences were noted using either a pool of healthy donors or a normal serum as reference controls. The average IU measured value for the assay cutoff (SRR 140%) corresponded to 9.54±1.68 mIU/L, and clinical application was shown in 60 Graves' patients. CONCLUSIONS: The TSAb bioassay demonstrated excellent performance in terms of linear range, limit of quantitation, and imprecision. The dilution experiments showed a high correlation coefficient and excellent reproducibility. Thus, TSAb levels can be reliably converted from SRR% to IU/L. These results offer the perspective of standardizing TSAb levels among laboratories and enable more accurate comparison of TSAb studies.