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

Background: Graves' 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. Methods: A 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. Results: Using 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. Conclusion: In 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.

Graves Disease Following Subacute Thyroiditis in a Chinese Man.

Background/Objective: The development of Graves disease (GD) after subacute thyroiditis (SAT) is rare, with approximately 31 reported cases, of which only 5 occurred in men. We describe a case of GD diagnosed based on newly elevated thyroid-stimulating immunoglobulin (TSI) and thyroid-stimulating hormone (TSH) receptor autoantibody (TRAb) levels after SAT. Case Report: A 32-year-old Chinese man presented with right anterior neck pain, swelling, sore throat, cough, and fever. He had a diffuse tender goiter but no proptosis, lid lag, or stare. His TSH level was 0.03 mIU/mL (normal range [NR] 0.45-5.33 mIU/mL), serum free thyroxine (FT4) level was 2.40 ng/dL (NR 0.61-1.44 ng/dL), total triiodothyronine (TT3) level was 113 ng/dL (NR 87-178 ng/dL), TSI level was <0.10 IU/L (NR < 0.10 IU/L), and erythrocyte sedimentation rate was 21 mm/h (NR < 15 mm/h). After 7 weeks of prednisone, the symptoms resolved, FT4 level was 0.95 ng/dL, and TT3 level was 91 ng/dL. At 11 weeks after SAT onset, the TSH level was <0.01 mIU/mL, TT3 level was 257 ng/dL, FT4 level was 3.03 ng/dL, TSI level was 1.94 IU/L, then 3.42 IU/L 2 weeks later, TRAb level was 8.72 IU/L (NR < 2 IU/L), and erythrocyte sedimentation rate was 4 mm/h. After 1 month of methimazole, the FT4 level was 1.32 ng/dL and TT3 level was 110 ng/dL. Genetic testing revealed human leukocyte antigen-B35 and DRB1∗15:01 positivity. Discussion: GD after SAT is thought to be due to the activation of thyroid autoimmunity induced by SAT in genetically susceptible individuals. Conclusions: This case illustrates the induction of thyroid autoimmunity after SAT, resulting in GD, supporting TSI and/or TRAb testing if hyperthyroidism recurs. The presence of HLA alleles associated with SAT and GD suggests a genetic contribution to the development of thyroid autoimmunity.

Thyroid-Stimulating Hormone Receptor Autoimmunity and Local Factors in Multiple Risk Factors Are Mainly Involved in the Occurrence of Pretibial Myxedema.

BACKGROUND: Pretibial myxedema (PTM) is a local mucinous dermopathy associated with thyroid diseases. Since the etiology of PTM is unclear, the aim of this study is to identify the risk factors for PTM and their etiological roles in PTM occurrence. METHODS: A large-scale case-control study (n = 1,200) was performed to identify risk factors for PTM by calculating odds ratio (OR) values and 95% confidential intervals. The PTM group entered a glucocorticoid treatment trial. Patients with complete response were followed up to the first relapse in a cohort study. The relative risk (RR) values of the main risk factors were calculated for PTM relapse to test their etiological roles. RESULTS: Among the 19 factors, six risk factors were identified: thyroid-stimulating hormone (TSH) receptor antibody (TRAb) (OR 42.93), autoimmune thyroid disease (AITD) or AITD history (OR 10.30), local trauma (OR 6.55), venous stasis posture (OR 6.16), cigarette smoking (OR 4.48), and age (OR 1.05). Serum TRAb levels were positively correlated with the severity of PTM. Of note, 371/400 patients received glucocorticoid treatment, and 330 achieved complete response. The serum TRAb levels after treatment decreased dramatically compared with those before treatment. After stopping glucocorticoid treatment, serum TRAb levels increased significantly when PTM relapsed (P < 0.001). In 165 relapse cases, an increase in serum TRAb levels occurred first, followed by persistent venous stasis posture or local trauma and finally PTM. The RR of elevated serum TRAb levels was 6.73 in PTM relapse cases. In the elevated serum TRAb level group, the RRs of local trauma, venous stasis posture, and local trauma plus venous stasis posture were 8.81, 6.5, and 8.84, respectively, for PTM relapse cases. CONCLUSIONS: TSHR autoimmunity and local factors in the six identified risk factors are the main causes of PTM occurrence.

Development of Thyroid-Associated Ophthalmopathy in Patients Who Underwent Total Thyroidectomy.

PURPOSE: To report clinical characteristics of thyroid-associated ophthalmopathy (TAO) in patients who previously underwent total thyroidectomy for thyroid cancer or a benign mass of the thyroid. MATERIALS AND METHODS: Of the patients who were diagnosed with TAO from March 2008 to March 2012, we performed a retrospective chart review on those who had undergone total thyroidectomy for thyroid cancer or a benign mass of the thyroid before the occurrence of ophthalmopathy. RESULTS: Of the 206 patients diagnosed with TAO, seven (3.4%) met the inclusion criteria. The mean age of the subjects was 47.4 years, and all were female. Six patients were diagnosed with papillary thyroid cancer, and one was diagnosed with a benign mass. The duration between total thyroidectomy and onset of TAO ranged from 3-120 months (median 48 months). Ophthalmic manifestations varied among cases. Except for the patient who was diagnosed with a benign mass, all patients showed hyperthyroid status and were under Synthroid hormone treatment at the time of TAO development. Five of these six patients had positive levels of thyroid-stimulating hormone (TSH) receptor autoantibodies. CONCLUSION: TAO rarely develops after total thyroidectomy, and the mechanism of TAO occurrence is unclear. However, most patients showed abnormalities in thyroid function and TSH receptor autoantibodies.

Development of Thyroid-Associated Ophthalmopathy in Patients Who Underwent Total Thyroidectomy

PURPOSE: To report clinical characteristics of thyroid-associated ophthalmopathy (TAO) in patients who previously underwent total thyroidectomy for thyroid cancer or a benign mass of the thyroid. MATERIALS AND METHODS: Of the patients who were diagnosed with TAO from March 2008 to March 2012, we performed a retrospective chart review on those who had undergone total thyroidectomy for thyroid cancer or a benign mass of the thyroid before the occurrence of ophthalmopathy. RESULTS: Of the 206 patients diagnosed with TAO, seven (3.4%) met the inclusion criteria. The mean age of the subjects was 47.4 years, and all were female. Six patients were diagnosed with papillary thyroid cancer, and one was diagnosed with a benign mass. The duration between total thyroidectomy and onset of TAO ranged from 3-120 months (median 48 months). Ophthalmic manifestations varied among cases. Except for the patient who was diagnosed with a benign mass, all patients showed hyperthyroid status and were under Synthroid hormone treatment at the time of TAO development. Five of these six patients had positive levels of thyroid-stimulating hormone (TSH) receptor autoantibodies. CONCLUSION: TAO rarely develops after total thyroidectomy, and the mechanism of TAO occurrence is unclear. However, most patients showed abnormalities in thyroid function and TSH receptor autoantibodies.

Correlation between TSH receptor antibody assays and clinical manifestations of Graves' orbitopathy.

PURPOSE: To investigate an association between the levels of serum thyroid-stimulating hormone (TSH)-receptor autoantibodies (TRAbs) and Graves' orbitopathy (GO) activity/severity scores, and compare the performance of three different TRAb assays in assessing the clinical manifestations of GO. MATERIALS AND METHODS: Cross-sectional study. Medical records of 155 patients diagnosed with GO between January 2008 and December 2010 were reviewed. GO activity was assessed by clinical activity score (CAS) and severity graded with the modified NOSPECS score by a single observer. Serum TRAb was measured by three different methods: 1st generation thyrotropin-binding inhibitor immunoglobulin (TBII) assay (TRAb1st); 3rd generation TBII assay (TRAb3rd); and biological quantitative assay of thyroid-stimulating immunoglobulin (TSI) using Mc4-CHO cells (Mc4-CHO TSI assay). Results were correlated with scores of activity/severity of thyroid eye disease. RESULTS: All three assays (TRAb1st, TRAb3rd, and Mc4-CHO TSI) yielded results that were significantly positively correlated with CAS (ß=0.21, 0.21, and 0.46, respectively; p<0.05) and proptosis (ß=0.38, 0.34, and 0.33, respectively; p<0.05). Mc4-CHO TSI bioassay results were significantly positively correlated with all GO severity indices (soft tissue involvement, proptosis, extraocular muscle involvement, and total eye score; ß=0.31, 0.33, 0.25, and 0.39, respectively; p<0.05). CONCLUSION: Mc4-CHO TSI bioassay was superior over the two TBIIs in assessing active inflammation and muscle restriction due to GO, whereas TBII assay would be sufficient for evaluation of patients with proptosis.

Correlation between TSH Receptor Antibody Assays and Clinical Manifestations of Graves' Orbitopathy

PURPOSE: To investigate an association between the levels of serum thyroid-stimulating hormone (TSH)-receptor autoantibodies (TRAbs) and Graves' orbitopathy (GO) activity/severity scores, and compare the performance of three different TRAb assays in assessing the clinical manifestations of GO. MATERIALS AND METHODS: Cross-sectional study. Medical records of 155 patients diagnosed with GO between January 2008 and December 2010 were reviewed. GO activity was assessed by clinical activity score (CAS) and severity graded with the modified NOSPECS score by a single observer. Serum TRAb was measured by three different methods: 1st generation thyrotropin-binding inhibitor immunoglobulin (TBII) assay (TRAb1st); 3rd generation TBII assay (TRAb3rd); and biological quantitative assay of thyroid-stimulating immunoglobulin (TSI) using Mc4-CHO cells (Mc4-CHO TSI assay). Results were correlated with scores of activity/severity of thyroid eye disease. RESULTS: All three assays (TRAb1st, TRAb3rd, and Mc4-CHO TSI) yielded results that were significantly positively correlated with CAS (beta=0.21, 0.21, and 0.46, respectively; p<0.05) and proptosis (beta=0.38, 0.34, and 0.33, respectively; p<0.05). Mc4-CHO TSI bioassay results were significantly positively correlated with all GO severity indices (soft tissue involvement, proptosis, extraocular muscle involvement, and total eye score; beta=0.31, 0.33, 0.25, and 0.39, respectively; p<0.05). CONCLUSION: Mc4-CHO TSI bioassay was superior over the two TBIIs in assessing active inflammation and muscle restriction due to GO, whereas TBII assay would be sufficient for evaluation of patients with proptosis.

Heterogeneity of TSH Receptor Autoantibodies in Autoimmune Thyroid Disease / 대한내분비학회지

BACKGROUND: It has been known that most of thyroid stimulating antibodies (TSAbs) may interact with epitopes near N-terminal, and thyroid stimulation blocking antibodies (TSBAbs) near C-terminal on the extracellular domain of TSH receptor. However, many authors have reported different results about epitopes reacting with TSH receptor autoantibody (TRAb). TSBAbs inhibit thyroid stimulation of TSH and TSAbs at the receptor level. However, it has been reported that there are some TSBAbs which bind to the other sites, not TSH receptor, or block post-reeeptor process. These findings raise the possibility that TRAbs may be heterogeneous according to the mechanism of action. In order to investigate the heterogeneity of TRAb, we undertook immuno-precipitation using synthetic peptides of TSH receptor and measured TRAb activities by FRTL-5 cells and chimeric CHO cells. METHODS: We studied 102 patients with autoimmune thyroid disease (Graves disease 32, Hashimotos thyroiditis 29, atrophic thyroiditis 41) and 35 healthy persons. Three synthetic peptide fragments of TSH receptor were used to perform immunoprecipitation with serum or IgG of patients and healthy persons, TSAb and TSBAb activities were measured by FRTL-5 cells and CHO cells transfected with wild-type and 2 mutant TSH receptor cDNA (Mc2, Mc1+2). Mc2 and Mcl+2 were rnade to substitute amino acid residues of 90-165, 8-165 of the TSH receptor with corresponding residues of LH/CG receptor, respectively. RESULTS: Two out of 10 IgGs extracted from Graves disease and 2 out of 9 IgGs from atrophic thyroiditis had specific bidings over 0.84% in immunoprecipitation with peptide I (amino acid residue 35-50). Four out of 18 IgGs from Graves disease, 9 out of 41 IgGs from atrophic thyroiditis, and 6 out of 14 IgGs from Hashimotos thyroiditis had specific bidings over 0.84% in immunoprecipitation with peptide II (amino acid residue 317-332). Only 2 out of 10 IgGs from Graves disease had specific bidings over 0.84% in immunoprecipitation with peptide III (amino acid residue 341-358). When 10 IgGs extracted from Graves disease were reacted with wild-type, Mc2, and Mcl+2 CHO cells, 7 IgGs in wild-type and 4 IgGs in Mc2 had positive for TSAb activities. In 10 IgGs from atrophic thyroiditis, 5 in wild-type, 5 in Mc2, and 3 in Mcl+2 CHO cells had positive for TSBAb activities. In Hashimoto's thyroiditis, only 1 with hyperthyroidism had positive for TSAb activity in wild-type and 1 with hypothyroidism had positive for TSBAb activities in both of wild-type and Mc2 CHO cells. Therefore, patients with Graves disease were divided into at least 3 groups according to the TSAb activities measured by wild-type, Mc2, Mcl+ 2 CHO cells and TBII activities. And patients with atrophic thyroiditis were divided into at least 4 groups according to the TBII activities, TSBAb activities by wild-type, Mc2, Mcl+2 CHO cells and FRTL-5 cells. CONCLUSION: From these results, epitopes of TSH receptor reacting with TSAb or TSBAb in autoimmune thyroid disease may be scattered in the TSH receptor, although epitopes of TSAb tend to be near N-terminal and those of TSBAb near C-terminal. Graves disease or atrophic thyroiditis were divided into 3 or 4 groups according to the TBII and TRAb activities. Therefore, TRAb detected in autoimmune thyroid disease may be heterogenous.