Thyrotrophin binding inhibiting immunoglobulins in Graves' disease before, during and after antithyroid therapy, and its relation to long-acting thyroid stimulator

Long-term remission following antithyroid drug withdrawal in patients with Graves' hyperthyroidism: parameters with prognostic value

OBJECTIVE

To assess the predictive value of some clinical and biochemical parameters, and of the +49 A/G polymorphism of the CTLA-4 gene, for long-term remission following the withdrawal of antithyroid drugs before starting antithyroid drug therapy.

STUDY DESIGN

Observational, prospective and longitudinal study.

METHODS

Seventy-two patients (11 of whom were men) with newly diagnosed Graves' hyperthyroidism who had been attended consecutively at a University Clinic in a population with sufficient iodine intake were included in the study.

EXCLUSION CRITERIA

patients under the age of 18, pregnant women and non-Caucasian patients. All subjects were treated following a well-defined protocol. Long-term remission was calculated at 12 and 36 months following withdrawal of the antithyroid drug.

RESULTS

Thirty-six of the 72 study subjects experienced a remission of at least 12 months following withdrawal of methimazole, with no differences according to their age or sex. A comparison made between the remission rates seen in both groups yielded significant differences regarding the presence of Graves' orbitopathy, the duration of the treatment with methimazole and the absence of the CTLA-4 G/G genotype. In the univariate and multivariate analyses performed, only lower frequencies of Graves' orbitopathy and an absence of the CTLA-4 G/G genotype were considered independent predictors of long-term remission.

CONCLUSIONS

The absence of Graves' orbitopathy and of the CTLA-4 G/G genotype are independent predictors of long-term remission following a first course of antithyroid drugs.

Remission of Graves' disease during anti-thyroid drug therapy. Time to reconsider the mechanism?

Therapy of Graves' hyperthyroidism with thionamide anti-thyroid drugs is accompanied by a gradual remission of the autoimmune aberration in the majority of patients. The most likely mechanism behind this remission has been considered to be a direct immunosuppressive effect of thionamide drugs. However, a number of findings in clinical studies of patients with Graves' disease indicate that remission is probably not caused by a special effect of thionamide drugs. Many studies have shown that remission is linked to restoration of the euthyroid state, and that it is independent of drug dose and type. Moreover, similar remission is observed when patients become euthyroid after thyroid surgery. In an explanatory model described, it is assumed that the autoimmune aberration of Graves' disease is often basically quit mild and self-limiting. Patients may become ill by the running of a vicious cycle of hyperthyroidism worsening the autoimmunity, and autoimmunity worsening the hyperthyroidism. Once patients are made euthyroid by one or the other drug or by thyroid surgery, the majority of patients will gradually enter remission of the disease. The conclusion that remission is associated with restoration of the euthyroid state, and that it is not a special drug effect, highlights the importance of making and keeping patients with Graves' disease euthyroid.

Concentration-dependent regulation of thyrotropin receptor function by thyroid-stimulating antibody

Thyrotropin receptor (TSHR) Ab's of the stimulating variety are the cause of hyperthyroid Graves disease. MS-1 is a hamster mAb with TSHR-stimulating activity. To examine the in vivo biological activity of MS-1, mice were treated with purified MS-1 intraperitoneally and the thyroid response evaluated. MS-1 induced a dose-dependent increase in serum thyroxine (T4), with a maximum effect after 10 proportional, variant g of MS-1 was administered. MS-1-secreting hybridoma cells were then transferred into the peritoneum of nude mice to study chronic thyroid stimulation. Serum MS-1 levels detected after 2 weeks were approximately 10-50 proportional, variant g/ml, and the serum TSH was suppressed in all animals. Serum triiodothyronine levels were elevated, but only in animals with low serum MS-1 concentrations. In addition, there was a negative correlation between serum T4 and the serum MS-1 concentrations. These in vivo studies suggested a partial TSHR inactivation induced by excessive stimulation by MS-1. We confirmed this inactivation by demonstrating MS-1 modulation of TSHR function in vitro as evidenced by downregulation and desensitization of the TSHR at concentrations of MS-1 achieved in the in vivo studies. Thus, inactivation of the TSHR by stimulating TSHR autoantibodies (TSHR-Ab's) in Graves disease patients may provide a functional explanation for the poor correlation between thyroid function and serum TSHR-Ab concentrations.

Changes in serum TSH receptor antibody (TRAb) values in patients with Graves' disease after total or subtotal thyroidectomy

TSH receptor antibodies (TRAb) are generally regarded as mediators of thyroid stimulation in Graves' disease. In addition, a high serum TRAb value during pregnancy is one of the risk factors for intrauterine death, prematurity, and fetal or neonatal hyperthyroidism. Recently, correlations between a high serum TRAb value and endocrine opthalmopathy were also suggested. Surgical resection of the thyroid is usually followed by a reduction of serum TRAb levels in variable degrees. The relation between the extent of the thyroidectomy and the degree of reduction is still controversial. In addition, the changes in the TRAb value after total thyroidectomy (TT) over a long period of time have never been studied. We studied the changes in serum TRAb values after TT and subtotal thyroidectomy (ST) for more than 7 years. Forty-one patients with Graves' disease underwent TT, and 99 patients underwent ST. The serum TRAb values and the ratio of the patients who achieved normal values among each group (normalization rates of TRAb) at 3 and 6 months, 1, 3, 5 and 7 years after surgery were compared between the TT group and ST group. The mean preoperative TRAb values were not significantly different between the TT and ST groups, and the mean TRAb values measured 3, 6 and 12 months after surgery were not significantly different between the groups. However, the TRAb values measured 3, 5 and 7 years after surgery were significantly (p<0.05) lower in the TT group than in the ST group (16.7 +/- 3.3% vs 28.0 +/- 2.6%, 12.6 +/- 3.4% vs 29.3 +/- 3.8%, 5.6 +/- 0.9% vs 25.4 +/- 4.1%, respectively). The normalization rates of TRAb were not significantly different between the groups until 1 year after surgery. However, the normalization rates 3, 5 and 7 years after surgery were significantly (p<0.05) higher in the TT group than in the ST group (65.7% vs 42.4%, 77.3% vs 46.7%, 100% vs 59.1%, respectively). The surgical complication rates of TT were similar to ST except for permanent hypoparathyroidism. TT is a treatment option for Graves' disease, especially in patients with a high TRAb value who wish to have children or who have Graves' opthalmopathy.

[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.

Immunological findings and thyroid function of untreated Graves' disease patients with undetectable TSH-binding inhibitor immunoglobulin

OBJECTIVE

TSH-binding inhibitory immunoglobulin (TBII) is undetectable in about 10% of untreated Graves' disease patients, but the clinical characteristics and immunological significance of this finding are unknown. In this study we evaluated the clinical characteristics of TBII negative Graves' disease.

PATIENTS

We examined TBII in 1048 untreated patients at Kuma hospital from 1986 to 1990 and found 69 TBII undetectable patients (12 men and 57 women, mean age +/- SEM 35 +/- 2 years, group A).

MEASUREMENTS

We compared the clinical characteristics and immunological findings of group A with 57 untreated TBII detectable Graves' patients who were selected randomly (11 men and 46 women, mean age +/- SEM 40 +/- 2 years, group B). T4, TSH, FT4, FT3, 123I thyroid uptake, TBII, thyroid stimulating antibodies (TSAb) and the volume of the thyroid using ultrasonography were measured at the first visit.

RESULTS

Serum T4, FT4 and FT3 levels in group A were significantly lower than those in group B (P < 0.001). The values of TSAb in group A were significantly lower than those in group B (593 +/- 67 (mean +/- SE) vs 2143 +/- 280%, respectively, P < 0.001). The 123I thyroid uptake in group A was significantly lower than that in group B (53.1 +/- 1.1 vs 61.4 +/- 1.4%, respectively, P < 0.01). The thyroid volume in group A was significantly smaller than that in group B (39.1 +/- 3.0 vs 51.3 +/- 3.3 ml, respectively, P < 0.01). TSAb was undetectable in about 10% (6) of the TBII negative untreated Graves' patients at their first visit.

CONCLUSION

In the present study, untreated TBII negative patients with Graves' disease were characterized by mild elevation of thyroid hormones, mildly elevated 123I uptake, weak TSAb activities and small goitres. The finding of both TBII and TSAb negative titres in untreated Graves' disease patients was also confirmed.

Thyroid disorders in Chinese patients with systemic lupus erythematosus

To clarify the prevalence of thyroid disorders in Chinese patients with systemic lupus erythematosus (SLE), 45 SLE patients not receiving corticosteroid therapy for at least 6 months were selected over a period of 1 year. They were investigated by utilizing thyroid ultrasonography and by determinations of thyroid antibodies and thyroid function. Of these patients, 24 (53.3%) showed abnormal sonographic findings. Thyroid antibodies (microsomal and/or thyroglobulin) were detected in 21 patients (46.7%), but a low index of thyrotropin-binding inhibitory immunoglobulin (TBII) was found in only one euthyroid patients with a normal echogram. Ten patients (22.2%) had abnormal thyroid function. The mean disease duration was longer in patients with thyroid anomalies (p < 0.05). Hashimoto's thyroiditis was found in four patients (8.8%), two of whom had hypothyroidism. We concluded that thyroid anomalies are frequently found in patients with SLE in the area of this study. The possibility of the coexistence of thyroid disorders in systemic lupus erythematosus should be carefully considered throughout the course of patients' follow-up, especially in those with a long disease duration.

Clinical course and thyroid stimulating hormone (TSH) receptor antibodies during surgical treatment of Graves' disease

This study assessed the results of surgical treatment for Graves' disease in our hospital and examined the relationship between the values of thyroid stimulating hormone (TSH) receptor antibodies and postoperative thyroid function. From 1983 to 1988, subtotal thyroidectomy was performed in 313 patients with Graves' disease. The follow-up rate was 89.1% (278 of 313 patients). Thirteen (4.2%) patients required methimazole postoperatively for hyperthyroidism and 23 (7.3%) patients required L-thyroxine postoperatively for hypothyroidism. The relationship between the postoperative thyroid function and TSH receptor antibodies was examined. The pre-operative thyrotropin binding inhibitory immunoglobulin (TBII) value had no relationship to postoperative thyroid function. Only in the patients who were hyperthyroid postoperatively did the TBII value remain elevated, but the value decreased gradually in patients who were not hyperthyroid postoperatively. In 43 of 94 patients whose pre-operative TBII values were high, the postoperative TBII value normalized. The higher the preoperative TBII value, the longer time was required for it to normalize postoperatively. The postoperative thyroid stimulating antibody (TSAb) values were higher in patients who remained hyperthyroid than in the patients who were not hyperthyroid. In the patients who remained hyperthyroid postoperatively, there was a significant correlation between the postoperative TBII value and the TSAB value. In the patients who were hypothyroid postoperatively, the TSBAb values were negative. In patients undergoing surgical treatment of Graves' disease, the postoperative TBII and TSAb values were related to postoperative hyperthyroidism. The TSBAb value had no relationship to postoperative hypothyroidism.

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'.

Thyrotropin binding inhibiting antibody (TBIAb) in Graves' disease

To determine the nature of TBIAb in Graves’ disease, TBIAb was measured and correlated to various clinical, thyroid functional indices and thyroid autoantibodies. The incidence of TBIAb in untreated Graves’ patients, patients in treatment and those in remission was 70.9%, 53.1% and 19.2%, respectively. With respect to clinical indices, there was no correlation between TBIAb and the presence of exophthalmos or periodic paralysis, onset age, diseage duration or sex, but goiter size on initial examination did show significant correlation (r=0.95). Regarding the indices of thyroid function, 20min 99m-Tc uptake (r=0.28), free T4 index (r=0.39) and free T3 index (r=0.40) were well correlated to TBIAb activity. Also Grave’s patients with strong antimicrosomal activity exhibited a high incidence of TBIAb positiveness.

HLA-DR antigen expression on the thyrocytes of Graves' disease patients

To confirm the expression of HLA-DR antigen on the thyrocytes of Graves’ disease patients and study the relation between the degree of DR antigen expression and clinical or laboratory indices, double immunofluorescence and immunoenzymatic staining were performed on frozen thyroid sections. DR antigen was expressed on the thyrocytes of 8 of 11 patients with Graves’ disease (73%) but not found on the thyrocytes from 6 normal controls. The degree of DR antigen expression had no apparent correlation with the age, duration of the disease, activity of TBII, titers of antimicrosomal and antithyroglobulin antibody. There was no apparent spatial or quantitative relation between lymphoid follicle formation and the DR antigen expression on the thyroid follicles. But DR antigen tended to be expressed on the thyroid tissue with interstitial, lymphocyte infiltration. In conclusion, DR antigen was expressed on the thyrocytes of Graves’ disease patients but the clinical and immunological significance remains to be clarified.

Autoimmune thyroid disease: immunological, pathological, and clinical aspects

Autoimmune thyroiditis, most notably Hashimoto's thyroiditis, appears to be increasing in prevalence and is now more easily detected by sensitive laboratory tests and more invasive procedures such as fine needle aspiration. During the last decade, marked progress has been made in the understanding of these diseases. There is a greater awareness of the interaction between the humoral and cell-mediated arms of the immune system in autoimmune thyroiditis. Recent studies implicate a subpopulation of suppressor T lymphocytes which have an antigen-specific defect, resulting in their suboptimal interaction with the helper T lymphocytes and subsequent autoimmune manifestations. There is some evidence that thyroid epithelial cells which inappropriately express HLA-DR may enhance presentation of thyroid antigens to the immune system, possibly significant in the initiation or enhancement of the autoimmune response. The presence of various antithyroid autoantibodies allows the use of laboratory assays to confirm the clinical diagnosis and predict the results of treatment. There appears to be predisposing genetic factors in the development of autoimmune thyroiditis, with some geographical and racial differences. Environmental factors, most notably dietary intake of iodine, have also been implicated in the pathogenesis of Hashimoto's thyroiditis. Several animal models have been developed addressing such issues. Ongoing studies in the areas of postpartum thyroiditis and childhood thyroiditis are helpful in clarifying their relationship with Hashimoto's thyroiditis. Graves' disease and postpartum thyroiditis are being investigated as possible causes of postpartum depression. The association of Hashimoto's thyroiditis and carcinoma of the thyroid gland is still controversial, but its relationship with malignant lymphoma is now well accepted. Thus, although the pathogenesis of autoimmune thyroiditis remains elusive, there has been significant refinement of the clinical diagnosis, and immunological abnormalities of specific intrathyroidal lymphocytes have been identified. Hopefully, these new areas of knowledge will assist in the treatment of these diseases and in the prevention of the development of malignant lymphomas of the thyroid gland.

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)

Further evaluation of an immunoprecipitation assay for TSH-receptor autoantibodies in Graves' disease

In ten patients with untreated Graves' disease, quantitative titers of TSH receptor antibodies, as measured by a recently developed immunoprecipitation assay (IPA), were correlated with results obtained in three other methods and with the severity of the hyperthyroidism, as assessed by thyroid function tests. Nine patients were positive in the IPA, six in the TBII (TSH-binding inhibitor immunoglobulins), six in the TSI (thyroid-stimulating immunoglobulins), and seven in the TGI (thyroid-growth stimulating immunoglobulins) assay. Three patients were positive in all four assays. No correlation was found between the IPA values and the results obtained in the TBII, TSI, or TGI assays. There was a modest correlation between the TBII and TSI assays (r = .74, P less than 0.02). There was a modest but significant correlation between the IPA titers of TSH receptor antibodies and serum T3 concentration, both before treatment (r = .63, P less than 0.05) and during treatment (n = 5; r = .84, P less than 0.05). No correlation between the severity of the hyperthyroidism and TBII, TSI, or TGI assays was observed. Finally, TGI did not correlate with goiter size as estimated by palpation. These results suggest that the IPA may be useful in monitoring the immunologic activity of TSH receptor antibodies in patients with Graves' disease. They suggest further that the IPA detects a number of different subpopulations of TSH receptor antibodies, including TSI, TBII, and perhaps TGI. This property may be particularly useful in screening for monoclonal TSH receptor antibodies.

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)

Graves' disease and Hashimoto's thyroiditis: effects of high doses of antithyroid drugs on thyroid autoantibody levels

We studied the effects of high doses of methimazole (MMI) or propylthiouracil (PTU) on thyroid-stimulating antibody (TSAb), antithyroid microsomal (MCHA) and antithyroglobulin (TGHA) levels in Graves' disease and Hashimoto's thyroiditis. Thirty Graves' hyperthyroid patients were treated for 14 +/- 8 months (mean +/- SD) with MMI, 60-80 mg daily or PTU, 900-1200 mg daily plus T3, 50-75 micrograms daily. Fifteen Hashimoto's thyroiditis patients (4 of whom hypothyroid) received 100-200 micrograms of T4 daily for 4-8 weeks prior to MMI, 60-90 mg daily or PTU, 900 mg daily for 12-16 weeks. In Graves' disease a decrease (p less than 0.001) in TSAb activity (20/25 patients) was observed: before therapy, 0.424 +/- 0.506 pmoles/mg wet wt and at the end of treatment, 0.189 +/- 0.23 pmoles/mg wet wt. The MCHA titers also fell (18/26 patients) from 1:10,403 +/- 20,197 to 1:3,476 +/- 5,252 (p less than 0.01) and was associated with a decrease in free T4 values (1.23 +/- 0.69 vs. 0.51 +/- 0.36 ng/dl; p less than 0.01). A fall of MCHA titers in T4-treated Hashimoto's thyroiditis patients (1:10,416 +/- 25,576) was found when compared with the value before T4 (1:25,920 +/- 39,973; p less than 0.001). However, the titers of MCHA (1:13,280 +/- 25,992) did not change on MMI or PTU plus T4 treatment. The TGHA titers fell in a single patient. No alterations were observed in serum immunoglobulins. Serum concentrations of the complement factor C'3 remained higher (p less than 0.01) than normal values in both Graves' disease and Hashimoto's thyroiditis.(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.

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.

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

In 1976 we initiated a prospective study to specify the usefulness of thyroid stimulating antibody (TSAb) determinations in predicting the outcome of post-antithyroid drug treatment for Graves' disease. This study was carried out on 55 patients, who were either treated for six (n = 16) or 18 months (n = 39) and followed up for an additional two-year period. TSAb was determined on whole serum in 29 patients before and at the end of treatment, and in 26 patients at the end of treatment only. These determinations were carried out using a sensitive and reproducible microassay based on cAMP accumulation in human thyroid cell cultures. Before treatment, TSAb ranging from 170 to 1529% was present in 28/29 patients and reached significantly low levels at the end of treatment whatever its duration. TSAb was undetectable in 24/55 patients at the end of treatment. 8/16 'short-treated' and 18/39 'long-treated' patients remained in remission. As expected, initial TSAb levels had no predictive value. End-treatment TSAb values, when low (less than 350%) or negative did not correlate with later evolution: in these 39 patients, relapse rate was 41%. In contrast, 13/16 patients with end-treatment TSAb greater than 350% relapsed. Relapses tended to occur earlier in patients with the highest TSAb levels. TSAb determined again during follow-up was negative in each of the 18 patients in remission, and positive in 8/10 patients at the time of relapse, whatever its level at the end of the drug course. This study confirms that only end-treatment TSAb levels are predictive of relapse.(ABSTRACT TRUNCATED AT 250 WORDS)

10 years experience with consecutive measurement of thyrotropin binding inhibiting antibodies (TBIAb)

In the present study we reviewed 230 patients in whom thyrotropin-binding inhibiting antibodies (TBIAb) follow-up determinations had been performed up to 10 yr after hyperthyroidism had first developed. In 104 patients, Graves' ophthalmopathy occurred at some time in the course of the observation period. Fourty-four of these patients with Graves' ophthalmopathy had at least one, and up to four relapses after each one-year course of antithyroid drug therapy with methimazole. The addition of TBIAb-positive results over an observation period of 1-10 yr showed positive cumulative findings in 95% of the 44 patients with recurrences of Graves' disease. A single TBIAb determination during hyperthyroidism showed positive results in 70%. A detailed breakdown showed that TBIAb was detectable during all hyperthyroid phases in 48% of the patients with ophthalmopathy. Thirty-four per cent of the patients had sometimes positive, sometimes negative TBIAb findings in the various hyperthyroid states. In 18% of the patients, TBIAb was not detected in any of the hyperthyroid phases. However, some of these patients became TBIAb-positive for the first time during antithyroid drug therapy or during a remission confirmed by a suppression test. Only 2 of the 44 patients never had TBIAb positive results at any time during the observation period. In those patients without ophthalmopathy during the observation period, the "cumulative" frequency of TBIAb was 74% for patients with diffuse goiter and 52% for patients with diffuse-nodular goiter. However, in patients with ophthalmopathy, there was no difference in TBIAb detectability between those patients with a diffuse and those with a diffuse-nodular thyroid.(ABSTRACT TRUNCATED AT 250 WORDS)

Syndrome of persisting thyroid stimulating immunoglobulins and growth promotion of goiter combined with low thyroxine and high triiodothyronine serum levels in drug treated Graves' disease

Among 48 Graves' patients treated with antithyroid drugs there were 8 patients with a further growth of an already enlarged goiter and a persistence of thyroid stimulating immunoglobulins (TSI). TSI activity did not persist in a comparison group of patients with less severe initial symptoms and an uncomplicated course during a similar regimen of drug treatment. Thyrotoxicosis was difficult to control in this subgroup of patients as low serum T4 was accompanied by borderline high T3 levels although TSH in serum remained undetectable. In spite of comparable low doses of antithyroid drugs serum T4 in the complicated group remained significantly lower (58 +/= 15 nmol/I SD vs. 97 +/- 19 nmol/I SD, p less than 0,001) and serum T3 stayed significantly higher (3,66 +/- 0,49 nmol/I SD vs. 2,15 +/- 0,50 nmol/I SD, p less than 0,001) than in the group with uncomplicated treatment. It is discussed that the promotion of goiter growth could be due to growth stimulating antibodies, and that a local intrathyroidal iodide depletion during antithyroid drug treatment might cause the shift from T4 to T3 production in this entity of Graves' patients.

Consistency and variability in the character of thyrotrophin receptor antibodies in Graves' disease

At diagnosis there was no correlation between the uptake of pertechnetate by the thyroid and thyrotrophin receptor antibodies (TRAb) measured as TSH binding inhibitory immunoglobulins in a series of 27 patients with Graves' disease. TRAb were detectable initially in 19 patients, in 11 of these there was a significant positive correlation (P less than 0.05) between serial measurements of pertechnetate uptake and TRAb made during 2 years following diagnosis. In five patients pertechnetate uptake fell with time whilst TRAb levels were maintained or fluctuated. In the remaining three of the 19 patients both measurements were low and did not change during treatment. We conclude that TRAb in any individual patient are a mixture of immunoglobulins of variable effectiveness as thyroid stimulators. In a majority of patients the composition of this mixture remains constant during the course of the illness and the clinical state reflects the levels of TRAb in the blood. In a minority, however, the character of these antibodies may alter with time or there is a change in the responsiveness of the thyroid gland. The general lack of correlation between measurements of thyroid stimulating activity and TSH binding inhibitory immunoglobulins in groups of patients is due to differences between patients in the composition of TRAb.

Thyroid function and immunological activity during and after medical treatment of Graves' disease

The variable clinical course of Graves' disease has been followed in 27 patients each studied for 2 years from the time of diagnosis. Thyroid hormone synthesis was blocked with large doses of antithyroid drugs for the first 12 months while euthyroidism was maintained with triiodothyronine. The latter was given alone from 12 to 18 months, and for the last 6 months the patients received no treatment. The activity of the disease was determined by repeated measurements of thyroid uptake of pertechnetate and by assay of thyrotrophin receptor antibodies (TSH binding inhibitory immunoglobulins). Retrospectively there were no features on presentation which singly or in combination indicated the clinical outcome: 16 patients remained in remission (Group 1) whilst in 11 hyperthyroidism had recurred before the end of the study (Group 2). Both measures of disease activity (thyroid uptake and antibody levels) fell during the first 12 months in patients of both groups. Recurrence of Graves' disease could be predicted in some but not all patients of Group 2 at 12 months by higher thyroid uptakes and levels of thyrotrophin receptor antibodies. There was, however, evidence of abnormal thyroid function, from which we infer continuing activity of the disease, 12 to 18 months after diagnosis in all patients of Group 1, even though these patients had normal TRH tests during the last phase of the study. The difference in the course of Graves' disease 12 to 24 months after diagnosis between those patients who remained in remission and those who did not was relative: in no patient was completely normal physiological control of thyroid function re-established. Clinical remission from hyperthyroidism at this time is a level of disease activity at which the normal physiological output of thyroid hormones is not exceeded.

The effects of sulphydryl reagents on the neutralization of LATS by human thyroid extracts

LATS has already been shown to be neutralized by an unknown antigenic substance in human thyroid tissue. This antigen has been presumed to be a TSH receptor. To examine this hypothesis, we sought to determine whether SH reagents capable of altering the characteristics of TSH receptors in thyroidal crude membrane fractions caused an alteration in the LATS neutralization activity of the same fraction. Diamide (10(-3) M) which was shown to enhance 125I-TSH binding to TSH receptors by increasing the binding affinity of the receptor, significantly increased the neutralization of LATS by the crude membrane fraction. Dithiothreitol (10(-3) M) which was shown to inhibit 125I-TSH binding by decreasing the affinity of the receptor, significantly decreased the neutralization of LATS by the fraction. This indicates that TSH receptors and the thyroidal factor capable of neutralizing LATS share a common property in terms of the effects of SH reagents and is compatible with the idea that the lats neutralizing activity of thyroidal crude membrane fraction is due to binding by the TSH receptor or its fragments.

A stable, reproducible radioreceptorassay for thyrotropin binding inhibiting immunoglobulins (TBII)

A radioreceptorassay for thyrotropin binding inhibiting immunoglobulins (TBII) is presented. A stable reproducible method was established based on the use of thyroid glands obtained by autopsy for the preparation of a highly purified plasma membrane from human thyroid homogenate. Lower detection limit for TSH was below 5 miu/l. The TBII activity was measured in a crude IgG precipitate from serum and the results were calculated as an index value compared to normal controls, the mean of which was defined as 1.00. The binding of [125I] TSH to this membrane preparation was stable for more than 6 months. Interassay variations of the TBII index in three ranges were 1.30 +/- 0.19, 0.37 +/- 0.08 and 0.04 +/- 0.07 (mean +/- SD) over a period of 6 months. The intra-assay variations of the TBII index in three ranges were 1.30 +/- 0.08, 0.46 +/- 0.03 and 0.09 +/- 0.03 (mean +/- SD). Seventy-six of 116 patients with untreated Graves' disease had index values below the reference interval and TBII was also detected in 4 of 14 patients with multinodular goitre. The value of the TBII index in patients with untreated Graves' disease was significantly correlated to S-T3, the 4 h [131I] uptake and the 20 min [99mTc] uptake. No significant correlation between the TBII index and long-acting thyroid stimulator (LATS) measured in a bioassay was found. However, the LATS-positive patients also had positive TBII index.

Comparison between thyroid stimulating and tsh-binding inhibiting immunoglobulins of Graves' disease

In the sera of patients with Graves' disease abnormal thyroid 'stimulating' immunoglobulins have been demonstrated by in vivo and in vitro assay systems. Conflicting results have been reported when thyroid stimulating and thyrotrophin (TSH)-binding inhibiting activities have been compared. The present study was performed in forty-nine hyperthyroid Graves' patients to ascertain the relationships among TsH-binding inhibiting immunoglobulins (TBII), measured by a radio-receptor assay, thyroid stimulating antibody(TSAb), assayed by stimulation of adenylate cyclase-cAMP system in human thyroid plasma membranes, and LATS, measured by McKenzie's mouse bioassay.TBII was detected in twenty-one of forty-nine (42.9%), TSAb in thirty-five of forty-nine (71.4%) and LATS in nineteen of forty-nine (38.8%).TBII was also present in four of sixteen (25%) patients with other thyroid autoimmune disorders. When the results obtained with the different techniques were compared, correlation was found between LATS response and TSAb activity ( =0.53, P less than 0.001), while there was no correlation between TSAb and TBII activities and between LATS response and TBII activity. These data conform that TSAb is specific and sensitive marker of Graves' disease and suggest that TBII activity is not necessarily synonymous with thyroid stimulation, and could reflect a different phenomenon concomitantly produced.

A comparative study of the binding of Graves' immunoglobulins by the patients own and other thyroid membranes

Thyroid membrane preparations from six patients with active Graves' disease were tested in an assay which detects the thyroid interactive immunoglobulins of Graves' disease by their inhibition of binding of [125I]-thyroid stimulating hormone (TSH). With all preparations inhibition of binding of 125I-TSH by excess TSH could be demonstrated (specific binding). The patients' own immunoglobulins were assayed against their own thyroid membranes and against each other's under exactly comparable conditions. Inhibition of binding by IgGs from the patients varied between membrane preparations: with one preparation 5/6 IgGs were inhibitory but with another none were effective. Of the six patients, their own IgG inhibited binding of 125I-TSH to their own thyroid membrane preparation in only four instances, and when interaction did occur this did not reliably predict that the membrane preparation would interact with IgGs from other patients with Graves' disease. The selection of a membrane preparation for this assay cannot be made solely on ability to specifically bind TSH but the measure of the specific interaction with a Graves' IgG of proven potency must also be considered. Moreover, because of the variability between different membrane preparations, sequential clinical studies on individual patients, of the changes in concentration of Graves' IgG, must be performed using the same selected thyroid membrane preparation. We infer from these observations that the membrane structure in the vicinity of the TSH binding site is an important determinant of the interaction of Graves' IgGs with the TSH receptor, and that the configuration of this area is variable between individuals of the same species. The distinction between 'human-specific' and 'non-species-specific' thyroid stimulating antibodies is therefore probably not valid. The observation that the patient's own IgG was not often the most potent IgG inhibitor of binding of TSH also suggests that the Graves' IgG binding site is not identical or restricted to the TSH binding site; alternative explanations are discussed.

Influence of treatment with radioiodine and propylthiouracil on thyroid stimulating immunoglobulins in Graves' disease

Thyroid stimulating immunoglobulins (TSAb) were measured in fifty-four patients with Graves' disease before treatment with either radioiodine (seventeen patients) or propylthiouracil (PTU) (thirty-seven patients), and followed during treatment. After radioiodine TSAb increased to levels exceeding pretreatment values, and became detectable in three of six originally TSAb negative patients. In most patients TSAb decreased during treatment with PTU, and became undetectable after a mean of 12 months in patients above 40 years, and after a mean of 6 months in patients below 40 years. In order to eliminate the presumed causative agent in Graves' disease, antithyroid treatment should be at least 18 months in patients above 40 years, and at least 12 months in patients below 40 years of age. In twenty-nine patients TSAb were measured at cessation of 2 years antithyroid drug therapy. Ten patients were TSAb positive and all except one relapsed. Five of nineteen TSAb negative patients relapsed. Although TSAb positivity predict relapse, it is not an ideal index of prognosis after antithyroid therapy.