Thyroid stimulating antibodies: an aid to the strategy of treatment of Graves' disease?

Prediction for recurrence following antithyroid drug therapy for Graves' hyperthyroidism

Objective

A common problem with antithyroid drugs (ATD) treatment in patients with Graves' disease (GD) is the high recurrence rate after drug withdrawal. Identifying risk factors for recurrence is crucial in clinical practice. We hereby prospectively analyze risk factors for the recurrence of GD in patients treated with ATD in southern China.

Subjects and methods

Patients who were newly diagnosed with GD and aged > 18 years were treated with ATD for 18 months and followed up for 1 year after ATD withdrawal. Recurrence of GD during follow-up was assessed. All data were analyzed by Cox regression with P values < 0.05 considered statistically significant.

Results

A total of 127 Graves' hyperthyroidism patients were included. During an average follow-up of 25.7 (standard deviation = 8.7) months, 55 (43%) had a recurrence within 1 year after withdraw of anti-thyroid drugs. After adjustment for potential confounding factors, the significant association remained for the presence of insomnia (hazard ratio (HR) 2.94, 95% confidence interval (CI) 1.47-5.88), greater goiter size (HR 3.34, 95% CI 1.11-10.07), higher thyrotrophin receptor antibody (TRAb) titer (HR 2.66, 95% CI 1.12-6.31) and a higher maintenance dose of methimazole (MMI) (HR 2.14, 95% CI 1.14-4.00).

Conclusion

Besides conventional risk factors (i.e., goiter size, TRAb and maintenance MMI dose) for recurrent GD after ATD withdraw, insomnia was associated with a 3-fold risk of recurrence. Further clinical trials investigating the beneficial effect of improving sleep quality on prognosis of GD are warranted.

Risk Factors for the Relapse of Graves' Disease Treated With Antithyroid Drugs: A Systematic Review and Meta-analysis

PURPOSE

Antithyroid drugs (ATDs) are the first-line treatment for Graves' disease (GD). A common problem with ATD treatment is the high relapse rate after drug withdrawal. The goal of this study was to analyze the influencing factors for the relapse of GD patients treated with ATD by using a systematic review and meta-analysis, provide some predictive indexes for the susceptibility of GD recurrence, and then further explore some useful methods to decrease the GD relapse rate after ATD treatment.

METHODS

Articles published in PubMed, EMBASE, The Cochrane Library, China National Knowledge Infrastructure, Wan Fang, and Chinese Biomedical Literature databases before January 2019 were collected. Patients newly diagnosed with GD, who were aged >16 years, were treated with ATD. Follow-up was then conducted for at least 12 months after ATD withdrawal. Only prospective or retrospective studies were eligible. The primary end point was the recurrence of GD during follow-up. All the data from the trials were analyzed via meta-analysis and meta-regression. p values < 0.05 were considered statistically significant, and statistical heterogeneity was assessed by using I² statistics.

FINDINGS

A total of 20 studies and 3242 patients were involved in this meta-analysis, with 1681 patients relapsed (incidence rate, 51.9%) during the follow-up time. Analysis of risk factors suggested that younger age (weighted raw mean difference [RMD], -3.51; 95% CI, -5.74 to -1.29), larger thyroid volume (RMD, 4.38; 95% CI, 1.68 to 7.08), bigger goiter size (1.94% risk; 95% CI, 0.43 to 3.46), higher free triiodothyronine level (RMD, 5.09; 95% CI, 4.42 to 5.77), and higher free thyroxine level (RMD, 4.21; 95% CI, 0.54 to 7.89) were associated with the higher relapse rate of GD. The block-replace ATD regimen (a fixed high dose of an ATD with levothyroxine supplementation to maintain euthyroidism) (risk ratio, 0.64; 95% CI, 0.52 to 0.78) exhibits a lower relapse rate than the titration regimen (an ATD used alone and dose adjusted according to thyroid function tests).

IMPLICATIONS

This analysis revealed that certain risk factors were associated with GD relapses such as younger age, larger goiter size or thyroid volume, and the higher free triiodothyronine or free thyroxine level in the diagnosing phase of GD. For patients with these clinical characteristics, early definitive treatment with radioactive iodine or surgery should be offered to those who are unlikely to achieve remission with ATDs only. In addition, more prospective cohort studies with different ATD regimens would help to determine the optimum ATD treatment for patients with GD. PROSPERO identifier: CRD 42019146825.

Novel Application of Quantitative Single-Photon Emission Computed Tomography/Computed Tomography to Predict Early Response to Methimazole in Graves' Disease

Objective

Since Graves' disease (GD) is resistant to antithyroid drugs (ATDs), an accurate quantitative thyroid function measurement is required for the prediction of early responses to ATD. Quantitative parameters derived from the novel technology, single-photon emission computed tomography/computed tomography (SPECT/CT), were investigated for the prediction of achievement of euthyroidism after methimazole (MMI) treatment in GD.

Materials and Methods

A total of 36 GD patients (10 males, 26 females; mean age, 45.3 ± 13.8 years) were enrolled for this study, from April 2015 to January 2016. They underwent quantitative thyroid SPECT/CT 20 minutes post-injection of ^99mTc-pertechnetate (5 mCi). Association between the time to biochemical euthyroidism after MMI treatment and %uptake, standardized uptake value (SUV), functional thyroid mass (SUVmean × thyroid volume) from the SPECT/CT, and clinical/biochemical variables, were investigated.

Results

GD patients had a significantly greater %uptake (6.9 ± 6.4%) than historical control euthyroid patients (n = 20, 0.8 ± 0.5%, p < 0.001) from the same quantitative SPECT/CT protocol. Euthyroidism was achieved in 14 patients at 156 ± 62 days post-MMI treatment, but 22 patients had still not achieved euthyroidism by the last follow-up time-point (208 ± 80 days). In the univariate Cox regression analysis, the initial MMI dose (p = 0.014), %uptake (p = 0.015), and functional thyroid mass (p = 0.016) were significant predictors of euthyroidism in response to MMI treatment. However, only %uptake remained significant in a multivariate Cox regression analysis (p = 0.034). A %uptake cutoff of 5.0% dichotomized the faster responding versus the slower responding GD patients (p = 0.006).

Conclusion

A novel parameter of thyroid %uptake from quantitative SPECT/CT is a predictive indicator of an early response to MMI in GD patients.

TSH Isoforms: About a Case of Hypothyroidism in a Down's Syndrome Young Adult

Background. For unknown reasons, the prevalence of thyroid autoimmune disorders is higher in patients with Down's syndrome than in the general population. The present case strongly supports a recent evaluation of propagating screening for thyroid disease in this group of patients to assure early diagnosis of hypothyroidism. Methods. In a 25-year-old man diagnosed with Down's syndrome, clinical manifestations of hypothyroidism were lacking, but profound biochemical abnormalities were found with particularly high levels of thyroid stimulating hormone (TSH). Antigenic properties of TSH were characterized using a panel of anti-TSH antibodies. Results. Technical problems not infrequently associated with TSH measurements are convincingly ruled out. Antigenic characterization of the patient's circulating TSH revealed circulating forms of TSH different from pituitary TSH which closely resembled TSH recombinant human hormone. Conclusions. It appears counterintuitive that the bioactivity of TSH decreases in the hypothyroid state as higher bioactivity of TSH is anticipated in hypothyroidism promoted by an increased hypothalamic TRH drive. In contrast, diminished negative thyroid hormone feedback will enhance posttranslational glycosylation of TSH subunits and increase sialylation of the carbohydrate side chains. Both exert a negative effect on TSH bioactivity, only compensated by the very high levels of the hormone as in the present case.

Use of an artificial neural network to predict Graves' disease outcome within 2 years of drug withdrawal

BACKGROUND

Graves' disease (GD) is an autoimmune disorder characterized by hyperthyroidism, which can relapse in many patients after antithyroid drug treatment withdrawal. Several studies have been performed to predict the clinical course of GD in patients treated with antithyroid drugs, without conclusive results. The aim of this study was to define a set of easily achievable variables able to predict, as early as possible, the clinical outcome of GD after antithyroid therapy.

METHODS

We studied 71 patients with GD treated with methimazole for 18 months: 27 of them achieved stable remission for at least 2 years after methimazole therapy withdrawal, whereas 44 patients relapsed. We used for the first time a perceptron-like artificial neural network (ANN) approach to predict remission or relapse after methimazole withdrawal. Twenty-seven variables obtained at diagnosis or during treatment were considered.

RESULTS

Among different combinations, we identified an optimal set of seven variables available at the time of diagnosis, whose combination was useful to efficiently predict the outcome of the disease following therapy withdrawal in approximately 80% of cases. This set consists of the following variables: heart rate, presence of thyroid bruits, psycological symptoms requiring psychotropic drugs, serum TGAb and fT4 levels at presentation, thyroid-ultrasonography findings and cigarette smoking.

CONCLUSIONS

This study reveals that perceptron-like ANN is potentially a useful approach for GD-management in choosing the most appropriate therapy schedule at the time of diagnosis.

Importance of the Detection Method for Thyroglobulin Antibodies for the Validity of Thyroglobulin Measurements in Sera from Patients with Graves Disease

Background: The use of recovery tests has been proposed to disclose interferences from anti-thyroglobulin antibodies (TgAbs) in thyroglobulin (Tg) assays. We studied the value of a recovery test in Tg measurement by a new commercial IRMA.

Methods: Blood samples were collected from 153 patients with untreated Graves disease. Tg and TgAbs were measured by IRMA and RIA, respectively (Dynotest Tg-plus and Dynotest anti-Tgn; Brahms Diagnostica). The recoveries of added amounts of Tg were calculated for each serum.

Results: TgAbs were detected in 72 of the 153 patients (47%). The recovery test results for the 81 TgAb-negative sera (median, 101%; range, 80–115%) were identical to the results for the 91 controls (median, 102%; range, 80–124%). By contrast, significantly lower recovery test results were observed for the 72 TgAb-positive sera (median, 79%; range, 60–103%; Z = −8.363; P &lt;0.0001). In the 34 of the 72 TgAb-positive sera with a normal recovery test, Tg concentrations were significantly lower (median Tg, 13.6 μg/L; range, 1.1–360 μg/L) than those measured in the TgAb-negative sera (median, 107 μg/L; range, 1.2–700 μg/L; Z = −3.797; P &lt;0.0001).

Conclusions: Tg values were decreased in TgAb-positive sera even when the results of the recovery tests were normal. This test should not be used alone to determine the validity of a serum Tg measurement in Graves disease.

Clinical validity of a new commercial method for detection of TSH-receptor binding antibodies in sera from patients with Graves' disease treated with antithyroid drugs

In this work, we compared the activities of TSH binding inhibitory immunoglobulin (TBII) results obtained with a new human TBII assay (h-TBII) using the human recombinant TSH receptor with thyroid stimulating antibodies (TSAbs). Sera were obtained from 90 patients with Graves' disease before and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). Before treatment, h-TBII were detected in 89/90 patients (98.9%) whereas TSAb activity was positive in 88/90 patients (97.7%). The two parameters fell during therapy. At the end of treatment, only h-TBII levels were significantly different between patients in remission and those in relapse (Z=-2.212; P=0.0270). The relapse rate in the patients with positive antibodies at drug withdrawal was significantly increased (chi(2)=6.057; P=0.0139 for h-TBII and chi(2)=8.988; P=0.0021 for TSAb). Most of patients (76%) relapsed during the 2 years following drug withdrawal. h-TBII or TSAb values were positive in 84.6% or in 80.8% of patients at the time of relapse. There was a significant correlation between the two antibody measurement methods before treatment, at drug withdrawal and at the time of relapse. These results indicate that the new TBII assay using human TSH receptor is as sensitive as the TSAb assay. Because of its much easier performance, it may advantageously replace TSAb measurement especially for the Graves' disease diagnosis and in the prediction of short-term relapse at the end of treatment.

Clinical value of a new TSH binding inihibitory activity assay using human TSH receptors in the follow-up of antithyroid drug treated Graves' disease. Comparison with thyroid stimulating antibody bioassay

First, to evaluate the performance level of a new TSH binding inhibitory antibody assay using human recombinant TSH receptors (h-TBII) in comparison with a thyroid stimulating antibody (TSAb) bioassay performed before, at the end of treatment (18 months) and after antithyroid drug withdrawal in Graves' disease patients; second, to assess the accuracy with which h-TBII levels could predict relapse and remission. Retrospective study on serum samples of Graves' disease patients treated by antithyroid drugs for 18 months. Serum samples from 140 patients (27 men and 113 women; median age 42 years) with recent onset hyperthyroidism due to Graves' disease were retrospectively tested for h-TBII at diagnosis, at 18 months and for 76 of them 6, 12, 24 and 36 months after drug withdrawal or at relapse. TSAb were also evaluated at each time. Thyroid blocking antibodies (TBAb) were measured in sera positive for h-TBII and negative for TSAb. h-TBII levels were measured with a radioreceptor assay using the human recombinant TSH receptor (DYNOtest TRAK human from B.R.A.H.M.S. Diagnostica, Berlin, Germany). TSAb and TBAb levels were assayed in thyrocyte cultures. At diagnosis, high levels of h-TBII were found in 138 of 140 patients with Graves' disease (98.6%). High TSAb values were also detected in the same 138 patients. The h-TBII and TSAb values were significantly correlated (r = 0.582, p < 0.0001). At 18 months, h-TBII were found in 48 of the 140 patients (34%) and TSAb in 43 patients (31%). The h-TBII and TSAb values were significantly correlated (r = 0.618, p < 0.0001) and fell significantly between diagnosis and 18 months (Z = - 9.84, p < 0.0001 and Z = - 9.19, p < 0.0001). TBAb were found in two of the 11 sera positive for h-TBII and negative for TSAb. At diagnosis, the median levels of h-TBII and TSAb were not significantly different between the patients who relapsed within the 3 years after the withdrawal of treatment (n = 60) and those who did not (n = 80) (Z = - 1.1, ns; Z = - 0.216, ns). At 18 months, the prevalences of h-TBII and TSAb were significantly increased in patients who relapsed compared to those who remained in remission at 3 years (60% vs. 15%, chi2 = 30.8, p < 0.0001 and 55% vs. 13%, chi2 = 29.1, p < 0.0001, respectively). h-TBII and TSAb median levels were also significantly increased in patients who relapsed compared to the others (Z = - 4,8, p < 0.0001; Z = - 3,01, P < 0.005). Among the 60 patients who relapsed, 36 (60%) displayed h-TBII and 33 (55%) TSAb at 18 months. The majority of patients who relapsed during the 2 years following the end of treatment, in contrast to those who relapsed later, were positive for h-TBII (67% vs. 27%, chi2 = 6.01, p = 0.035). Seventeen of the 18 tested patients who relapsed were negative for h-TBII at 18 months, were then positive for h-TBII at the time of relapse, whereas 15 of them were still negative, 6-12 months before the relapse. Among the 80 patients who remained in remission at 3 years, only 10 (13%) displayed TSAb and 12 (15%) h-TBII at 18 months. In 10 of these 12 patients who were further evaluated for h-TBII positivity, h-TBII fell to control levels during the 3 years following the end of treatment. The new h-TBII assay is a simple and rapid method with a performance level similar to that of TSAb determination. Its sensitivity is close to 100% at diagnosis. In the whole group, TBII level analysis is relevant as a predictor for short time relapse. However, some of the patients are "misclassified", due to the inter-individual variability in the time course of h-TBII activity. Our results confirm that, in addition to h-TBII, even when measured with a highly sensitive test, the concomitant analysis of other clinical and/or biological parameters is necessary to improve the prediction of treatment outcome.

[Recurrence and prognostic factors after treatment with antithyroid agents in Graves-Basedow disease. Multicenter study in Northern Spain]

Therapy with anti-thyroid drugs is the initial option mostly used in our country for the treatment of hyperthyroidism due to Graves-Basedow disease. To evaluate the long term results of this kind of therapy, a total of 773 patients were studied who were diagnosed from 1975 to 1994 in three hospitals in Northern Spain (Hospital Central de Asturias, Hospital de Cruces and Hospital de Navarra) after a mean follow-up time after anti-thyroid drug withdrawal of 46 +/- 33.1 months. The results showed a likelihood of hyperthyroidism relapse of 42.9%, 59.8%, 67.9% and 78.9% at one, three, five and ten years, respectively. Goitre size was correlated very significantly with the likelihood of relapse (p < 0.0001). In contrast, only TBII positivity at the end of therapy among the remaining parameters (age, sex, goitre size, length of therapy, positivity of anti-thyroid antibodies and TBII) influenced significantly on the relapse likelihood (p < 0.05). In conclusion, after a long term follow-up after anti-thyroid therapy, a high relapse rate of hyperthyroidism in Graves-Basedow disease, which amounts up to 79% at ten years, was observed. Goitre size was the main predictive factor for this relapse.

Use of Chinese hamster ovary cell lines transfected with cloned human thyrotropin receptor for the measurement of thyroid-stimulating antibodies: advantages and difficulties

We compared the activities of thyroid-stimulating antibodies (TSAb) as measured with two cell lines (JP26 and JP26/26) transfected with cloned human thyrotropin (TSH) receptor and the values for TSAb measured on human thyrocytes cultures. Sera were obtained from patients with Graves' disease, before, during and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). The activities of TSAb performed with the three assays correlated significantly. The TSAb technique using JP26/26 cells was as sensitive as the method performed on human thyrocyte cultures since positive TSAb values were found in 45 out of 47 (95.7%) newly diagnosed patients, in 100% of patients who relapsed after drug withdrawal and in none in remission. When the JP26 cell line was used, sensitivity decreased as the detection rate was only 53.2 and 55.5% before treatment and in case of relapse, respectively. The TSH receptors analysis showed a receptor density two times higher for JP26/26 than for JP26. JP26/26 cells provide similar diagnostic information on human thyrocytes in patients with Graves' disease. Moreover with these cells, the procedure for cell culture is less cumbersome and precision is better. However, rigorous culture conditions are required to maintain TSH receptor expression in transfected cells.

Antithyroid drugs and Graves' disease--prospective randomized assessment of long-term treatment

OBJECTIVE

Although antithyroid drugs (ATD) are widely used in the treatment of Graves' disease, management protocols, especially treatment duration, remain a subject of debate. The rate of relapse after short-term regimens of less than 6 months with ATD at decreasing doses is higher than after longer treatments from 12 to 24 months. As no prospective study has provided data on even longer protocols exceeding 2 years, we conducted a prospective trial to determine potential benefits of a 42-month treatment compared with an 18-month treatment.

DESIGN, PATIENTS AND MEASUREMENTS

The aim of this prospective randomized trial was to compare relapse rates achieved two years after treatment withdrawal in patients who received carbimazole at decreasing doses for 18 months (n = 62) vs 42 months (n = 72). In addition to clinical relapse rate, the percentage of patients who normalized antithyroperoxidase (TPO) antibody and anti-TSH receptor stimulating antibody (TSAb) levels and early iodine uptake at the end of treatment were assessed as outcome criteria.

RESULTS

The relapse rate two years after discontinuation of treatment did not differ significantly in patients treated for 18 months from those treated for 42 months (36% vs 29%, NS). At the end of treatment, there was no significant difference between the two groups in the percentage of anti-TPO positive patients (53% vs 46%, NS) or early iodine uptake (27% vs 21%, NS). Although the percentage of patients with TSAb was significantly lower in the 42-month treatment group (18% vs 42%, P = 0.004) at treatment withdrawal, the percentage of TSAb-positive patients did not significantly decrease between 18 and 42 months in this group (27% vs 18%, NS).

CONCLUSION

Treatment duration greater than 18 months did not improve remission rate determined 2 years after treatment withdrawal or immunological variables or early iodine uptake measured at the time of discontinuation of treatment. These findings would indicate that, when a defined duration treatment is planned, prolonging treatment beyond 18 months does not provide any additional benefit.

The prognostic value of thyrotropin receptor antibody measurement in the early stages of treatment of Graves' disease with antithyroid drugs

In most trials, at least 50% of patients with Graves' disease treated with antithyroid drugs (ATD) relapse after achieving euthyroidism. At present, there are no definitive prognostic parameters available early in treatment to indicate those likely to achieve long-term remission. Because thyrotropin receptor antibodies (TRAb) are specific for Graves' disease, the possibility that their rate of change early in treatment (0 to 6 months) might be such an indicator was explored. TRAb were measured both as thyrotropin binding inhibitory immunoglobulins (TBII) and as thyroid-stimulating antibodies (TSAb) in 85 patients with untreated Graves' disease at 6-month intervals throughout their ATD treatment. The patients in the study were treated for a minimum period of 12 months and were categorized retrospectively into two groups depending on whether or not they remained in remission after ATD treatment. Remission was deemed as reached in patients who remained euthyroid for a minimum period of 15 months after cessation of ATD. The mean initial TBII and TSAb values in the nonremission group were significantly higher than in the remission group (p < 0.001 for both parameters). The rates of fall in mean TBII levels were similar for each group in the first 6 months of treatment, but while they continued to fall in the remission group over the next 6 to 12 months, mean values for the nonremission group plateaued and failed to fall to control levels within that period. These results indicate that changes in TRAb levels, measured either as TBII or TSAb, occur more rapidly in the second 6 months of treatment in patients who ultimately achieve remission than those who do not. If TBII fall to control levels by 12 months, the patient has at least a 70% chance of ultimately achieving remission with ATD treatment alone.

Clinical validity of intercellular adhesion molecule-1 (ICAM-1) and TSH receptor antibodies in sera from patients with Graves' disease

We compared the concentrations of soluble intercellular adhesion molecule-1 (sICAM-1) and the activities of thyroid-stimulating antibodies (TSAb) and thyrotropin-receptor antibodies (TBIAb) as measured with a commercial kit (TRAK). Sera were obtained from patients with Graves' disease (GD) before, during and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). In all the situations, TSAb method was more sensitive than TBIAb. These two parameters dropped during therapy and were not correlated at any stage of measurement. sICAM-1 levels increased in 56.4% of patients before treatment, remained elevated at the beginning of treatment and decreased after twelve months of therapy. TSAb levels were significantly different between patients in relapse (78%) and those in remission (18%) (Z = -2.250, P = 0.025), with a relapse rate depending on the TSAb positivity (chi 2 = 7.103, P = 0.0077). Positive sICAM-1 values were found in 3 of the 9 (33.3%) patients who relapsed after discontinuing the drug but were negative in all the patients remaining in remission with a significant difference (Z = -1.982, P = 0.0475). The relapse rate was also dependent on positive sICAM-1 values (chi 2 = 3.958, P = 0.0466). No correlation was found between sICAM-1 levels and anti-TSH receptor antibodies TSAb or TBIAb. We conclude that the TBIAb technique is too insensitive to explore GD. TSAb and sICAM-1 assays in patients with GD are good markers of immune process after treatment withdrawal. Because of its rapid implementation, the sICAM-1 assay may advantageously replace TSAb measurement for forming a prognosis of GD.

Thyroid-stimulating antibody and TSH-binding inhibitor immunoglobulin in 277 Graves' patients and in 686 normal subjects

TSH receptor antibodies (TRAb) are believed to cause hyperthyroidism of Graves' disease. Thyroid-stimulating antibody (TSAb) and TSH-binding inhibitor immunoglobulin (TBII) have been measured as TRAb to diagnose Graves' disease and to follow Graves' patients. We intended to evaluate the clinical value of TRAb (TSAb and TBII) assay in establishing the diagnosis of Graves' disease and in predicting its clinical course. TSAb and TBII were studied in 686 normal subjects and in 277 Graves' patients before antithyroid drug therapy. We followed serial changes of TSAb and TBII in 30 Graves' patients before, during and after antithyroid drug therapy over 3.5-9 yr. We measured TSAb as a stimulator assay and TBII as a receptor assay. Both TSAb and TBII were distributed normally in 686 normal subjects. ROC curves demonstrated that both TSAb and TBII had high sensitivity and specificity for the diagnosis of Graves' disease, and were equally sensitive and specific; 150% was chosen as cut-off value for TSAb and 10% for TBII. Of the 277 untreated Graves' patients, 254 (92%) had positive TSAb and positive TBII. All of the 277 untreated Graves' patients had positive TRAb (TSAb and/or TBII). We followed the serial changes of TSAb and TBII in 30 Graves' patients over 3.5-9 yr. During antithyroid drug therapy, TSAb and TBII activities decreased and disappeared in 27 patients (Group A), but continued to be high in the other 3 (Group B). The former 27 Group A patients achieved remission, but the latter 3 Group B patients continued to have hyperthyroidism. Of the 27 Group A patients, 16 (59%) had parallel decreases of TSAb and TBII activities; in 6, the changes were predominantly observed in either TSAb or TBII, and in 4, complex changes in TSAb and TBII activities were observed. Disappearance of TSAb and appearance of TSBAb was seen in one. The other 3 Group B patients continued to have high TSAb and TBII activities and to have hyperthyroidism. In conclusion, TSAb and TBII are of clinical value in establishing the diagnosis of Graves' disease and in predicting its clinical course. We clearly demonstrated its diagnostic usefulness. Both TSAb and TBII have high sensitivity and specificity. All of the 277 untreated Graves' patients had TRAb (TSAb and/or TBII). Serial changes of TSAb and TBII during therapy differ from one patient to another, and can be classified into several groups. Changes in TSAb and TBII activities reflect the clinical courses of Graves' patients. The simultaneous measurement of both TSAb and TBII is clinically useful, since TSAb and TBII reflect two different aspects of TRAb. TSAb and TBII are different.

Clinical features of patients with Graves' disease undergoing remission after antithyroid drug treatment

The clinical course of 306 Graves' patients treated with methimazole (MMI) was reviewed with the aim of establishing criteria able to predict remission of hyperthyroidism after medical treatment. One hundred and ninety-four (149 females, 45 males) of 306 (63.4%) patients had relapse of hyperthyroidism after antithyroid drug (ATD) withdrawal. Relapse was more frequent during the first months of the follow-up, but still it was observed 3 years after MMI withdrawal. The relapse rate was dependent on the age of the patient, the size of goiter, and the level of TSH-receptor antibody (TRAb) at diagnosis, being observed in 40 of 47 (85%) patients with high (> 30 U/L) TRAb level and in 54 of 101 (53%) patients with low TRAb level (< or = 30 U/L; p <.0002). Remission was more frequent (43.3%) in patients having the combination goiter size < or = 40 mL, TRAb level < or = 30 U/L, than in patients with goiter size > 40 mL and high TRAb levels (9%). In the subgroup of patients with the combination: goiter < or = 40 mL- TRAb < or = 30 U/L - age at onset > 40 years, the remission rate was 80%, and all relapses occurred within the first 9 months after MMI withdrawal. In conclusion, our study confirms that hyperthyroidism relapses in the majority of patients with Graves' disease treated with ATD. Among different clinical and laboratory features, age at onset of hyperthyroidism, goiter size and TRAb level are particularly helpful in identifying those patients who are more prone to undergo a remission of hyperthyroidism after medical treatment and may be useful to select the minority of Graves' patients who will benefit from antithyroid drug treatment as a first choice.

Prognostic Value of Suppressed Thyrotropin Level and Positive Thyrotropin-Receptor Antibody Activity in Graves’ Disease with Long-Lasting Clinical Remission

OBJECTIVE

To determine the prognostic value of suppressed thyrotropin (TSH) level and positive TSH-receptor antibodies (TSH-R Ab) in patients with Graves' disease who have long-lasting clinical remission.

METHODS

We retrospectively studied patients with Graves' disease who underwent follow-up for a mean of 55 months after the withdrawal of antithyroid drug treatment. Study patients were 84 consecutive subjects in clinical remission, with normal serum free thyroxine (FT(4)) and free triiodothyronine (FT(3)) levels, regardless of serum TSH levels, a mean of 35 months (range, 6 to 135) after discontinuation of carbimazole therapy. Eighty-seven euthyroid subjects were used as control study participants. All subjects had serum determinations of FT(4) and FT(3) (radioimmunoassay), TSH (highly sensitive immunoradiometric method), TSH-R Ab (radioreceptor assay), and microsomal antibodies (M Ab, passive hemagglutination method).

RESULTS

In the study patients, serum TSH was suppressed (</=0.10 mU/L) in 13 cases (15%), TSH-R Ab were positive (>/=15%) in 11 cases (13%), and M Ab were positive (>/=1:100) in 54 cases (64%). Simultaneous suppressed TSH and positive TSH-R Ab levels were present in six patients. During the follow-up, 11 patients had a relapse, demonstrated by above-normal values for serum FT(4) and FT(3) in association with clinical symptoms of hyperthyroidism. Five of them had a previously suppressed TSH level, three had a positive TSH-R Ab level, and six had a positive M Ab titer. Relapse was significantly more likely in patients with a previously suppressed TSH level (P<0.02) but not in patients with a previously positive TSH-R Ab level or positive M Ab titer.

CONCLUSION

Patients with Graves' disease and long-lasting clinical remission after discontinuation of carbimazole therapy may have a suppressed TSH level, a positive TSH-R Ab level, or a positive M Ab titer (or some combination of these findings). Although positive TSH-R Ab and M Ab have no significant prognostic value, a suppressed TSH level is indicative of subclinical hyperthyroidism and higher risk of relapse.

Antithyroid drug and Graves' hyperthyroidism. Significance of treatment duration and TRAb determination on lasting remission

OBJECTIVE

To investigate the significance of treatment with antithyroid drugs longer than 12 months on lasting remission in Graves' hyperthyroid patients, and to study clinical and laboratory parameters of prognostic value.

PATIENTS

Fifty-two untreated Graves' hyperthyroid patients were assigned at random to two therapeutic groups. They were treated with carbimazole during 12 and 24 months in Group I (n = 28) and Group II (n = 24), respectively.

MEASUREMENTS

Serum levels of FT4, T3, sTSH and TSH receptor antibody (TRAb) were measured before starting treatment and at regular intervals during treatment and follow-up after drug withdrawal. We compared the relapse rate in both groups of patients, at short (2-yr) and long-term (5-yr) periods after drug withdrawal. Also, we compared clinical and biochemical parameters between patients who stayed in remission and who had relapse.

RESULTS

At the end of the short-term period, relapse had occurred in 13 (46.4%) Group I patients and in 13 (54.1%) Group II patients, p = 0.36. At the end of the long-term period, relapse had occurred in 24 (85.7%) Group I and 20 (83.3%) Group II patients, p = 0.78. No difference could be observed between patients who had stayed in remission and who had suffered relapse, within the 5-yr follow-up period regarding to goiter size, frequency of ophthalmopathy, TSH and TRAb levels.

CONCLUSIONS

The high relapse rate observed could be due to high iodine intake in our country. In this study and in a review of the available data, we have been unable to find any rational basis for courses of antithyroid drugs longer than twelve months for the treatment of Graves' hyperthyroidism.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti TSH-receptor antibodies in pregnant patients with autoimmune thyroid disorder

The study was designed to test further the usefulness of the radioreceptor assay of thyroid stimulating hormone (TSH) binding inhibitory immunoglobulins (TBII) and the bioassay of thyroid stimulating antibodies (TSAb) or TSH stimulated cAMP response inhibitory antibodies (TBkAb) in the prediction of neonatal thyroid dysfunction. Of 63 pregnant women with a current or past history of autoimmune thyroid disorder, 11 (one with active and six with a past history of Graves' disease and four with autoimmune thyroiditis) gave birth to a baby with transient hyper or hypo-thyroidism. Only high maternal titres (which could persist after partial thyroidectomy) of anti TSH-receptor antibodies (TRAb) led to neonatal hyperthyroidism. Both types of assay were able to detect the antibodies responsible for transitory neonatal autoimmune thyroid disease. TBII values reflected TSAb titres so that there was a significant correlation between the results of both assays in women with Graves' disease and in neonatal sera. Positive TBII and TBkAb activities were present in 5 of the 28 women with autoimmune thyroiditis. Therefore, when TBII is positive, the functional characterization of the antibodies warrants the use of the bioassay.

Evidence for several cell populations in human thyroid with distinct glycosphingolipid patterns

Thyrocytes, which are functional cells of human thyroid, have been isolated, and their glycosphingolipid content has been analyzed in the various fractions obtained from the digested gland as well as in the tissue remaining after enzymatic treatment. The ganglioside content was not significantly different in the different fractions, with GM3 and Gd3 as major components. Analysis of neutral glycolipids revealed striking differences between isolated thyrocytes and whole thyroid. The membraneous material released from the proteinase-treated thyroid presented a pattern of monohexosylceramides clearly distinct from that of thyrocytes. The present data suggest the presence of at least two cellular populations with distinct glycolipid patterns in thyroid tissue: accessory cells containing most of the glycolipids, and thyrocytes in which the major neutral glycosphingolipid is phytosphingosine-containing glucosylceramide.

Evaluation of TSH receptor antibody by 'natural in vivo human assay' in neonates born to mothers with Graves' disease

Neonatal thyrotoxicosis induced by transferred TSH receptor antibody (TRAb) is the ideal human in-vivo experimental system for the evaluation of TRAb. The clinical significance of circulating TRAb in Graves' disease was evaluated by this 'natural in-vivo human assay'. TRAb activity in vitro was measured by radioreceptor assay (thyrotrophin-binding inhibitor immunoglobulin, TBII) and sensitive cAMP accumulation assay using FRTL-5 cells (thyroid-stimulating antibody, TSAb). Further, the binding-stimulation index (B-S index) was newly introduced, which was the most useful indicator for prediction of neonatal thyrotoxicosis, calculated as the product of TBII and TSAb (Tamaki et al., 1988a). Maternal serum TRAb indices showed highly significant correlations with the serum free T4 index (FT4I) and free T3 index (FT3I) in neonates (5-10 days after birth) born to 20 mothers with Graves' disease who had positive TBII and/or TSAb (FT4I: r = 0.825 for TBII, r = 0.908 for TSAb, r = 0.944 for the B-S index, P less than 0.001; FT3I: r = 0.622 for TBII, P less than 0.01, r = 0.812 for TSAb, r = 0.791 for the B-S index, P less than 0.001; n = 20). In contrast, in 57 untreated adult patients with hyperthyroid Graves' disease, the FT4I and FT3I levels were not correlated with any of the TRAb indices. The linear regression relationship between the B-S index and FT4I found in neonates was applied to values in adult patients with Graves' disease, and the patients were divided into three groups on the basis of the 95% confidence limit: high, normal, and low responders of thyroid hormone (FT4I) secretion to the B-S index. FT4I and the ratio of FT4I to the B-S index were highest and the TRAb indices were lowest in the high responders, while FT4I and the FT4I/B-S index ratio were lowest and the TRAb indices were highest in the low responders. The FT4I/B-S index ratio was inversely correlated with the titres of antithyroid microsomal antibody in all the adult patients with untreated Graves' disease (r = -0.288, P less than 0.05). The results suggest that in-vitro assays using animal thyroid cells and cAMP as an index of response are suitable for detecting circulating thyroid stimulating activity in vivo. Secretion of thyroid hormones in Graves' disease may be regulated not only by circulating thyroid-stimulating antibodies but also by intrathyroidal stimulatory factors or by inhibitory or destructive factors.

Optimum duration of antithyroid drug treatment determined by assay of thyroid stimulating antibody in patients with Graves' disease

OBJECTIVE

To determine the optimal duration of antithyroid drug treatment by monitoring serum thyroid stimulating antibody values in patients with Graves' disease.

DESIGN

Prospective longitudinal trial of patients with Graves' disease followed up for 24 months after withdrawal of treatment.

SETTING

Tertiary referral centre.

PATIENTS

A total of 64 consecutive patients with untreated Graves' disease, eight of whom were subsequently excluded. Fifty six patients completed the study.

INTERVENTIONS

All patients were treated initially with carbimazole 40 mg, then with decreasing doses that maintained a euthyroid state. Treatment was scheduled to continue for 18 months but was withdrawn earlier if serum thyroid stimulating antibody became undetectable.

END POINT

Serum values of thyroid stimulating antibody (assayed by stimulation of human thyroid cells in vitro) and thyroid hormones and thyroid state every three months during treatment and afterwards every six months for 24 months.

MEASUREMENTS AND MAIN RESULTS

In 44 patients serum thyroid stimulating antibody became undetectable during treatment and treatment was withdrawn (median duration of treatment nine months, range 3-18 months). In 12 patients the antibody could be detected during 18 months of treatment. Among the first group of 44 patients initial values of the antibody before treatment were significantly lower than in the second group of 12 patients (median 225% (range 138-1236%) v 570% (250-1480%), p less than 0.001); the incidence of relapse was also lower (41% v 92%, p less than 0.001); and among those who did relapse the disease free interval after treatment was longer (median 12 months v 1 month, p less than 0.001). Moreover, the initial median serum values of thyroid stimulating antibodies were not related to the occurrence of relapse or remission as these did not differ between patients who did and did not have a relapse (median 267% (range 139-1480%) v 220% (range 138-1236%).

CONCLUSION

Monitoring of serum thyroid stimulating antibody was a good guide to the duration of treatment as it allowed the treatment period to be considerably shortened in a large group of patients with no loss of efficiency.

Assays of TSH-receptor antibodies in 576 patients with various thyroid disorders: their incidence, significance and clinical usefulness

The incidence and the significance of TSH-receptor antibodies in Graves' disease and in various thyroid disorders have been evaluated. TSH-binding inhibiting antibodies (TBIAb) and thyroid stimulating antibodies (TSAb) were detected in a large proportion of Graves' disease patients (TBIAb in 68.8% and TSAb in 77.8%), in a small number of patients with idiopathic myxoedema or Hashimoto's thyroiditis, and were not detected in patients with endemic euthyroid goitre, differentiated thyroid carcinoma and toxic adenoma. Furthermore, TSH-receptor antibodies were present in some patients with toxic multinodular goitre (TBIAb in 12.7% and TSAb in 15.9%). When TSH-receptor and other thyroid autoantibodies were compared, it was found that 13 of the 15 Graves' patients with negative tests for thyroglobulin and thyroid microsomal antibodies were positive for TSH-receptor antibodies. On the other hand, 9 of the 11 patients with toxic multinodular goitre who had positive TSH-receptor antibody tests, also had serum thyroglobulin and/or thyroid microsomal antibodies. No significant differences in the prevalence of TSH-receptor antibodies were found in Graves' patients irrespective of the presence of ophthalmopathy or pretibial myxoedema. Elevated TBIAb activity at the end of anti-thyroid drug treatment was found in 52.9% of Graves' patients who subsequently relapsed, while in Graves' patients in remission TBIAb was always negative. TSH-receptor antibody results were not predictive of the outcome of radioiodine treatment in Graves' disease. Finally no correlation could be found between TBIAb and TSAb in Graves' disease and Hashimoto's thyroiditis.

IN CONCLUSION

the high incidence of TSH-receptor antibodies in Graves' disease confirms their pathogenetic role in the development of hyperthyroidism; TSH-receptor antibodies in Graves' disease are not significantly associated with the presence of ophthalmopathy or pretibial myxoedema; TSH-receptor antibody assays may be useful for the diagnosis of Graves' disease in the absence of other signs of autoimmunity. TBIAb seems to be a good predictor of relapse in Graves' patients treated with anti-thyroid drugs; a fraction of toxic multinodular goitre could be a nodular variant of Graves' disease.

TSH binding-inhibiting antibodies in hyperthyroidism: relationship to clinical signs and hormone levels

TSH binding-inhibiting antibody (TBIAb) activity was measured in 809 European patients with different forms of hyperthyroidism. Distribution of these TBIAb was skewed, with a peak in the range of normal controls, and an ill defined, not clearly separated peak at higher levels of TSH displacement. There was no unequivocal separation of two possible subgroups of hyperthyroidism (immunogenic and non-immunogenic). TBIAb distributions of patients with and without endocrine ophthalmopathy (EO) overlapped considerably. Although patients with Graves' disease, arbitrarily defined by the presence of endocrine ophthalmopathy or diffuse nuclide uptake by thyroid scanning, had mostly elevated TBIAb activity, 24.3% had values within the range of normal controls (mean + 2SD). Patients with diffuse thyroid uptake had significantly higher TBIAb levels than patients with nodular scan findings. In Graves' disease, TBIAb activity was positively correlated with the severity of endocrine ophthalmopathy, the size of the thyroid, and the serum levels of total and free triiodothyronine. There was no influence of age, sex, pretreatment, or regional iodine supply. These results suggest (1) that the clinical manifestations of Graves' disease are statistically related to TBIAb activity and (2) that separation of immunogenic and non-immunogenic forms of hyperthyroidism by means of TBIAb determination is unsatisfactory. The almost continuous distribution of TBIAb points to insufficient sensitivity of the present technique and raises doubts as to whether TBIAb values can be reliably classified as 'positive' or 'negative'.

Rapid effectiveness of prednisone and thionamides combined therapy in severe amiodarone iodine-induced thyrotoxicosis. Comparison of two groups of patients with apparently normal thyroid glands

Treatment of amiodarone iodine-induced thyrotoxicosis is often unsuccessful. Nevertheless, severe forms require a rapidly efficient therapy. Twelve patients with severe amiodarone iodine-induced thyrotoxicosis, as demonstrated on clinical and biological findings, were studied. After amiodarone withdrawal, 6 patients (group A) were treated with thionamides alone (carbimazole 60 mg daily and benzylthiouracile 1.5 g daily), and 6 patients (group B) received in addition to the same antithyroid drugs prednisone, 0.50 to 1.25 mg/kg/day for 40 days; in group A, T4 levels did not change over the study period of 40 days; T3 levels decreased only after 30 days; clinical status did not improve. In group B: T3 and T4 levels decreased dramatically at 10 days of treatment, to values significantly lower than in group A; clinical improvement occurred mainly in patients treated with high doses of prednisone; elevated thyroglobulin levels diminished rapidly. Improvement was maintained after cessation of prednisone. The rapid effect of prednisone suggests an impairement of proteolysis of thyroglobulin possibly due to a lysosomal action.

The relationships between serum T3 index, thyroid volume, and thyroid stimulating, TSH receptor binding and thyroid growth stimulating antibodies in untreated Graves' disease

This study represents an international double-blind collaborative study of abnormal immunoglobulin activity in untreated Graves' disease. Laboratories in two countries participated in a comparison of thyrotrophin binding inhibiting (TBII), thyroid stimulating (TSAb), and growth stimulating (TGI) immunoglobulins with clinical data, including ultrasonically measured thyroid size. The correlation between TGI and thyroid volume (n = 25, Rs = 0.54, P less than 0.05) and the fact that 9 of 10 patients with high range TGI values had large goitres establish the relationship between TGI and goitre, confirming that the in-vitro activity of these antibodies is related to an in-vivo action. In addition, both TBII and TSAb correlated with serum free T3 indices (TBII: n = 60, Rs = 0.46, P less than 0.001, and TSAb: n = 60, Rs = 0.64, P less than 0.001). Moreover, both TBII and TSAb correlated with thyroid volume (TBII: n = 60, Rs = 0.37, P less than 0.01, and TSAb: n = 60, Rs = 0.41, P less than 0.01) suggesting that these antibodies are also important in development of goitre in Graves' disease. Finally, some correlation between the antibodies was observed. TBII correlated with TSAb (n = 60, Rs = 0.47, P less than 0.001), and in the 16 patients with positive TGI results, this activity correlated with TBII (Rs = 0.54, P less than 0.05), but not with TSAb. Also some cases were found with corresponding high range TBII and TGI, while negative for TSAb, suggesting a close relationship between the in-vitro measurement of TSH binding and TGI.

Cellular and humoral immunity in patients with hyperthyroid Graves' disease before, during and after antithyroid drug treatment

Many reports of thyroid stimulating immunoglobulins (TSI) in relation to treatment of Graves' disease have been published and with variable results concerning prediction of permanent remission or relapse after therapy. A range of methods has been used and little has been published measuring TSI by using their ability to stimulate cyclic AMP production in human thyroid cells in monolayer culture. We therefore conducted a prospective study of the predictive value of such an assay in patients with hyperthyroid Graves' disease before, during and after treatment of one year with methimazole and thyroid hormone substitution. Furthermore, the possible relationship between activated suppressor T lymphocytes and TSI in patients followed before, during and after medical therapy has been studied. Patients were divided into two groups; group I, 15 patients, who stayed in remission and group II, 14, who relapsed during the first year after discontinuation of therapy. Mean TSI activity did not differ between the two groups before and during the first half year of medication. In the second half year of treatment, however, mean TSI activity was significantly lower in group I. TSI activity at the end of treatment appeared to have no value in predicting final outcome. Increased TSI activity in group II during treatment was reflected in an increased pertechnetate thyroidal uptake as compared to that in group I. There was no relationship between changes in TSI activity and T cell subsets (Leu 1, 2a, 3a). We found no difference in T lymphocytes between the two groups at any time during observation. Subsets of T lymphocytes in both patient groups did not differ from normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective enrichment of phytosphingosine in glycosphingolipids of isolated human thyrocytes as compared to the whole thyroid

The glycosphingolipids of isolated human thyrocytes have been analyzed. As compared to the total thyroid gland, the pattern of gangliosides was found to be similar, whereas the neutral glycolipid profile was quite different, with glucosylceramide as the major glycosphingolipid of thyrocytes. Moreover, this glucosylceramide contains almost exclusively phytosphingosine (4-D-hydroxy-sphinganine) which is only a minor component in the long-chain bases of the glycosphingolipids extracted from the whole thyroid gland.

Thyroid-stimulating antibodies in patients with long-term remission of Graves' hyperthyroidism

The persistence of TSH receptor antibodies in Graves' disease despite the remission of hyperthyroidism has been described. Our study was designed to evaluate whether this extends to functionally active stimulators of the thyroid, since the occurrence of thyroid-stimulating antibodies (TSAb) in a euthyroid patient could well have important implications on our understanding of the pathogenetic role of such autoantibodies. Forty-four patients with a previous history of Graves' hyperthyroidism were reexamined after having been in long-lasting remission for 3 to 35 years (mean 8 years). Of the patients 16 had been treated by radioiodine, 17 by surgery, and 11 exclusively by antithyroid drugs. The determination of TSAb was based on T3 release from thyroid tissue in vitro to document the final response to these immunoglobulins. TSH-binding inhibiting immunoglobulins (TBII) were evaluated by a radioreceptor assay. TSAb were highly elevated in three of the 44 patients. These three patients showed a normal TSH response to i.v. TRH, suffered from endocrine ophthalmopathy, and had been treated by radioiodine for hyperthyroidism. TBII were found positive in seven patients including the three patients mentioned. The majority of patients positive for TSAb or TBII had been treated by radioiodine and none exclusively by antithyroid drugs. In conclusion, not only TBII but also T3 release-stimulating antibodies may occur in a minority of patients with long-term remission of Graves' hyperthyroidism. However, an absence of hyperthyroidism in these patients despite the presence of such thyroid stimulators seems to be only possible in association with a lack of functional responsiveness of the target organ due to previous administration of destructive therapies.(ABSTRACT TRUNCATED AT 250 WORDS)

[Determination of TSH receptor antibodies--clinical value]

In 223 patients suffering from Graves' disease, TSH receptor autoantibodies in serum were measured using the commercially available TRAK assay (Henning, Berlin). Of 53 patients examined before treatment, 50 (94%) were TRAK-positive. During drug therapy the number of positive titers decreased. Of 38 patients examined after a therapy course for the first time, only two (5.3%) were positive. Evaluation of antibody status after all three forms of treatment (drugs, surgery, radioiodine) in 146 patients showed that of 33 patients with persistently positive titers only nine relapsed. Of the 24 patients out of this group without relapse, 15 had operative or radioiodine treatment. The 113 patients becoming or remaining TRAK-negative after treatment showed 12 relapses, in all these cases relapse was accompanied or announced by conversion to positive TRAK values. The high sensitivity and specificity of the assay (in a control group of 40 patients with autonomous adenoma no positive TRAK was seen) allow to use the test for discrimination between Graves' disease and disseminated autonomy of the thyroid in patients presenting with diffuse hyperthyroidism. Thus, by helping to establish an exact diagnosis, TRAK could become important for therapy planning. Concerning relapse prediction, our data are less promising since only 39% of patients with persistently positive TRAK titers relapsed. TRAK is not a reliable indicator of relapse risk especially in patients operated or treated with radioiodine. On the other hand, 10% of patients showing negative titers after treatment also relapsed, all turning to positive TRAK values at the same time.

IgG thyrotrophin receptor antibody activity in Graves' disease; a study of TSH agonist and antagonist activities by isoelectric focusing

The distribution of TSH receptor antibody activity in the 7S and 19S fractions of Graves' sera has been re-evaluated. Serum fractions were obtained by gel filtration from 12 Graves' sera and assayed for TSH receptor binding activity in a radioreceptor assay. Thyroid stimulating activity was determined in a cultured porcine thyroid cell bioassay. In apparent contrast to the findings of Baker et al. (1983) TSH receptor binding activity was confined to the 7S gel filtration fraction, containing IgG, and was not detected in the 19S fraction, containing IgM. Similarly thyroid stimulating activity was detected only in the 7S fraction. 7S fractions from seven Graves' sera were fractionated by isoelectric focusing and the fractions analysed for TSH receptor binding activity and TSH agonist and antagonist activities. Five of the IgGs showed TSH agonist activity and in all five, the peak thyroid stimulating activity (measured by stimulation of cyclic AMP release from isolated porcine thyroid cells) was in fractions with a pI of between 8.0 and 9.5. In four of these five IgGs, TSH receptor binding activity showed similar isoelectric distribution to the thyroid stimulating activities. High levels of TSH receptor binding activity without associated TSH agonist or antagonist activity were however observed in some isoelectric fractions of the fifth stimulating Graves' IgG studied. All the isoelectric fractions from the fifth IgG with thyroid stimulating activities contained TSH receptor binding activity. Two of the Graves' IgGs showed TSH antagonist activity and both the TSH receptor binding and TSH antagonist activities of these IgGs showed similar isoelectric distribution with the peak activities at a pI of around 9.0. Consequently, it was not possible to separate TSH agonist or TSH antagonist activities from TSH receptor binding activity in seven Graves' sera by isoelectric focusing although in one IgG several isoelectric fractions contained isolated receptor binding activity. These findings are in keeping with the hypothesis that the biological activities of Graves' IgGs are intimately related to their ability to bind to the TSH receptor.

Prognostic value of thyroid stimulating antibodies and TSH-binding inhibiting immunoglobulins in the follow-up of Graves' disease

The prognostic value of the determinations of autoantibodies in Graves' disease is still questionable. So far, the role of different assay procedures used has not been intensively investigated. We simultaneously applied two different techniques, a radioreceptor assay and a T3 releasing in vitro assay, in the follow-up of patients with Graves' disease to directly compare the course of the antibody activities determined by these assays and to find out a prognostic significance of the composition of the antibody spectrum present. The initial activities of thyroid stimulating antibodies (TSAb) and TSH-binding inhibiting immunoglobulins (TBII) were not significantly correlated in patients before treatment. During a 12-month antithyroid medication antibody titres showed a concordant course in the majority of patients. In 6 of 25 patients, however, a discordant behaviour was clearly documented including dose-response curves. At the end of treatment, the patients could be divided into three groups: group I included 5 patients positive for both TSAb and TBII, group II 6 patients positive for TBII and negative for TSAb and group III 14 patients negative for both of them. During the following survey of 18 months all patients of group I, 2 patients of group II and 6 patients of group III experienced a relapse of hyperthyroidism. In conclusion, TSAb and TBII activities dissociate in some patients during antithyroid drug therapy. For the individual patient, the disappearance of both TSAb and TBII was no certain indicator for a longstanding remission of Graves' hyperthyroidism. The persistence of TSAb seems to be more reliably associated with persisting or rapidly relapsing disease than the persistence of TBII.

Technetium thyroid uptake ratios in pediatric Graves disease

Patients with Graves disease were prospectively followed by means of three 99mtechnetium thyroid uptake ratios. These three ratios were greater than 90% sensitive and specific for the detection of hyperthyroidism in the patient with untreated Graves disease. Twelve of 15 patients experienced prolonged remission after normalization of the ratios. These ratios exhibit significant linear correlation with serum thyroxine and triiodothyronine concentrations (r = 0.4-0.6, P less than 0.01) and are a very sensitive index of medical oversuppression of thyroid function.

An analysis of thyrotrophin receptor binding and thyroid stimulating activities in a series of Graves' sera

Improved receptor and bioassays have been used to compare TSH receptor binding and thyroid stimulating activities in unextracted sera from 110 patients with Graves' disease. The two parameters showed a significant correlation (r = 0.65; P less than 0.001) although there were some clear discrepancies. Dose-response studies in 17 sera showed that both receptor binding and thyroid stimulating responses always increased with increasing doses of serum. In patients who were in relapse or remission following antithyroid drug treatment, the results of both bio- and receptor assays correlated well with disease activity with only one clear discrepancy which could have been attributable to the coexistence of autoimmune stimulation and destruction of the thyroid.