TSH Receptor Antibody Activity Research Articles

Thyrotrophin receptor antibody concentration and activity, several years after treatment for Graves' disease.

TSH receptor antibodies (TRAb) are responsible for autoimmune hyperthyroid disease (Graves' disease; GD) with TRAb levels tending to decrease following treatment. Measurement of TRAb activity during follow-up could prove valuable to better understand treatment effectiveness. TRAb concentration and stimulating (TSAb) and blocking (TSBAb) activity of patient serum were assessed following different treatment modalities and follow-up length. Sixty-six subjects were recruited following treatment with carbimazole (n=26), radioiodine (n=27) or surgery (n=13). TRAb, TPOAb, TgAb and GADAb were measured at a follow-up visit as well as bioassays of TSAb and TSBAb activity. Forty-five per cent of all patients remained TRAb-positive for more than one year and 23% for more than 5years after diagnosis, irrespective of treatment method. Overall, TRAb concentration fell from a median (IQR) of 6.25 (3.9-12.7) to 0.65 (0.38-3.2) U/L. Surgery conferred the largest fall in TRAb concentration from 11.4 (6.7-29) to 0.58 (0.4-1.4) U/L. Seventy per cent of TRAb-positive patients were positive for TSAb, and one patient (3%) was positive for TSBAb. TRAb and TSAb correlated well (r=0.83). In addition, 38/66 patients were TgAb-positive, 47/66 were TPOAb-positive and 6/66 were GADAb-positive at follow-up. TRAb levels generally decreased after treatment but persisted for over 5years in some patients. TRAb activity was predominantly stimulatory, with only one patient demonstrating TSBAb. A large proportion of patients were TgAb/TPOAb-positive at follow-up. All treatment modalities reduced TRAb concentrations; however, surgery was most effective.

The thyroid function of Graves' disease patients is aggravated by depressive personality during antithyroid drug treatment

BackgroundWe previously reported that depressive personality (the scores of hypochondriasis, depression and psychasthenia determined by the Minnesota Multiphasic Personality Inventory (MMPI)) and daily hassles of Graves' disease (GD) patients treated long trem with antithyroid drug (ATD) were significantly higher in a relapsed group than in a remitted group, even in the euthyroid state. The present study aims to examine the relationship among depressive personality, emotional stresses, thyroid function and the prognosis of hyperthyroidism in newly diagnosed GD patients.MethodsSixty-four untreated GD patients responded to the MMPI for personality traits, the Natsume's Stress Inventory for major life events, and the Hayashi's Daily Life Stress Inventory for daily life stresses before and during ATD treatment.ResultsIn the untreated thyrotoxic state, depressive personality (T-scores of hypochondriasis, depression or psychasthenia greater than 60 points in MMPI) were found for 44 patients (69%). For 15 (23%) of these patients, the scores decreased to the normal range after treatment. However, depressive personality persisted after treatment in the remaining 29 patients (46%). Normal scores before treatment were found for 20 patients (31%), and the scores were persistently normal for 15 patients (23%). The remaining 5 patients (8%) had higher depressive personality after treatment. Such depressive personality was not associated with the severity of hyperthyroidism. Serum TSH receptor antibody activity at three years after treatment was significantly (p = 0.0351) greater in the depression group than in the non- depression group. The remission rate at four years after treatment was significantly (p = 0.0305) lower in the depression group than in the non- depression group (22% vs 52%).ConclusionThe data indicate that in GD patients treated with ATD, depressive personality during treatment reflects the effect of emotional stress more than that of thyrotoxicosis and that it aggravates hyperthyroidism. Psychosomatic therapeutic approaches including antipsychiatric drugs and/or psychotherapy appears to be useful for improving the prognosis of hyperthyroidism.

Persistence of Thyrotropin (TSH) Receptor Antibodies in Children and Adolescents with Graves' Disease Treated Using Antithyroid Medication

To determine the course of thyrotropin (thyroid-stimulating hormone [TSH]) receptor antibodies (TRAbs) in children and adolescents with Graves' disease treated using antithyroid drugs (ATDs). Retrospective, cross-sectional study of 86 children and adolescents with Graves' disease treated medically for >3 years. Patients with Hashimoto's thyroiditis and idiopathic short stature (n = 30) served as controls. A second-generation enzyme-linked immunosorbent assay (ELISA) for TRAbs was used. Twenty-two out of 23 (95.7%) patients with newly diagnosed Graves' disease, but 0/30 controls, had detectable TRAbs (22.0 +/- 13.5 U/L [mean +/- SD] vs. 0.9 +/- 0.9 U/L, p < 0.0001). Mean TRAb levels decreased with duration of therapy, but even after 13-24 months, TRAbs had normalized in only 3/16 (18.8%) patients. The initial TRAb titer correlated significantly with severity of the initial hyperthyroidism, but did not predict the response to therapy as indicated by the dosage of ATD required to control the hyperthyroidism at 6 and 12 months. Unlike adults, most children and adolescents with Graves' disease require >2 years of ATD treatment before TRAbs are normalized. Although initial TRAb activity reflects disease severity, it does not predict the response to medical therapy. Recommendations as to treatment duration developed for adult patients should not be applied to the young.

The relationship of psychological factors to the prognosis of hyperthyroidism in antithyroid drug-treated patients with Graves' disease.

The relationship between emotional stress and the onset of hyperthyroidism has been well investigated, but the relationship between psychological factors and prognosis of antithyroid drug-treated hyperthyroidism is not well known. This study has examined not only emotional stresses but also patients' personality traits using specific tests. A prospective cohort study. Sixty-nine patients with hyperthyroid Graves' disease in the euthyroid state after 2-5 years of antithyroid drug therapy and 32 healthy subjects as the control group. Patients responded to three types of questionnaires, including the Minnesota Multiphasic Personality Inventory for personality traits, the Natsume's Stress Inventory for major life events, and the Hayashi's Daily Life Stress Inventory for daily life stresses. In the Graves' disease patients, stress scores of life events correlated significantly with serum TSH receptor antibody activity (r = 0.424, P < 0.001) and thyroid volume (r = 0.480, P < 0.001). When the patients were divided according to prognosis (41 with relapse and 28 with remission), four personality traits including hypochondriasis, depression, paranoia and psychasthenia (mental fatigue) were significantly (P = 0.0146, 0.0052, 0.0125, and 0.0186, respectively) more common in the relapsed Graves' disease group than those of the remitted group. Six personality traits of conversion hysteria, psychopathic deviation, masculinity and feminity, schizophrenia, hypomania, and social introversion were not significantly different between the two groups. The scores of daily hassles (problems of daily life) were also significantly (P = 0.0124) greater in the relapsed Graves' disease group than in the remitted group. The scale scores of depression and psychasthenia showed a positive correlation with scores of daily hassles (r = 0.535, P < 0.0001; r = 0.580, P < 0.0001, respectively), while an inverse correlation with scores of daily uplifts (r = -0.373, P = 0.0332; r = -0.322, P = -0.0120, respectively). The results suggest that major life events, personality traits of hypochondriasis and depression, paranoia, mental fatigue, and daily problems aggravate the prognosis of antithyroid drug-treated hyperthyroidism. Escape from life events is virtually impossible; thus coping strategies suggested by the physician may be useful in improving prognosis in Graves' disease.

The formation of thyrotropin receptor (TSHR) antibodies in a Graves' animal model requires the N-terminal segment of the TSHR extracellular domain.

Immunization of AKR/N mice with murine fibroblasts, transfected with the TSH receptor (TSHR) and a murine major histocompatibility complex class II molecule having the same H-2k haplotype (but not either alone), induces immune thyroid disease with the humoral and histological features of human Graves', including the presence of two different TSHR antibodies (TSHRAbs): stimulating TSHRAbs, which cause hyperthyroidism; and TSH-binding-inhibiting immunoglobulins. The primary functional epitope for both types of antibodies in Graves' patients is on the N-terminal portion of the extracellular domain of the TSHR, residues 25 to 165; most require residues 90-165 to express TSHRAb activity, as evidenced in studies using chimeras of the TSHR and lutropin-choriogonadotropin receptor (LH-CGR). To evaluate the role of this region of the TSHR in the formation of Graves' TSHRAbs, we immunized AKR/N mice with fibroblasts transfected with three human TSHR chimeras with residues 9-165 (Mc1+2), 90-165 (Mc2), or 261-370 (Mc4) substituted by equivalent residues of the rat LH-CGR. Mice immunized with the Mc1+2 and Mc2 chimeras, with the N-terminal portion of the extracellular domain of the TSHR substituted by LH-CGR residues, did not develop TSHRAbs. Mice immunized with the Mc4 chimera, having a major portion of the C-terminal portion of the extracellular domain of the TSHR replaced by comparable LH-CGR residues, can develop TSHRAbs. The results suggest that the N-terminal segment of the TSHR extracellular domain is not only a critical functional epitope for Graves' TSHRAbs, but it is important also in their formation in a mouse model of Graves' disease.

Changes in epitopes for thyroid-stimulating antibodies in Graves' disease sera during treatment of hyperthyroidism: therapeutic implications.

To determine whether there are changes in epitope recognition by stimulating TSH receptor antibodies (TSHRAbs) during treatment of hyperthyroidism and to evaluate the clinical relevance of such changes, we serially measured the activity of IgG preparations from 39 patients with Graves' disease over an 8-month period. To measure epitope changes of the stimulating TSHRAbs, we used Chinese hamster ovary (CHO) cells transfected with wild-type human TSHR (hTSHR) or TSHR chimeras with residues 90-165 (Mc2) substituted by equivalent residues of the rat LH/CG receptor. When initially examined, 37 of the 39 patients had significant stimulating TSHRAb activity measured with wild-type CHO-hTSHR cells. Serial measurements of stimulating TSHRAb activity in Mc2 chimera-transfected cells divided the 39 patients into three distinct groups. Thus, 10 patients (heterogeneous epitope group) exhibited low but significant activity in Mc2 chimera assays at the start of the study; 10 patients who were initially negative in Mc2 chimera assays remained negative (persistently homogeneous epitope group); and 19 patients who were initially negative in Mc2 chimera assays became transiently or persistently positive during treatment, despite a simultaneous decrease in TSHRAb activity measured with wild-type TSHR (changing epitope group). The functional stimulating TSHRAb epitope thus changed from residues 90-165 to residues outside this region in the last group, which comprises nearly two-thirds of the initially Mc2-negative patients (19 of 29) and one-half of all patients (19 of 39). Patients in the changing epitope group responded more quickly and to lower doses of methimazole than patients in the persistently homogeneous epitope group, behaving in this respect exactly as the patients in the heterogeneous epitope group. Additionally, although the decrease in stimulating TSHRAb activities during the 8-month treatment period was similar in the two groups, the thyrotropin binding inhibitor immunoglobulin (TBII) activities decreased more rapidly in patients in the persistently homogeneous epitope group than in patients in the changing epitope group (P < 0.05). There were no differences in initial stimulating TSHRAb or TBII activities, degree of hyperthyroidism, goiter size, or prior duration of symptoms between the persistently homogeneous epitope group and changing epitope group. In summation, we show that the epitopes of stimulating TSHRAbs in Graves' disease patients may change during their clinical course or treatment period, and that the change is from antibodies recognizing N-terminal TSHR residues 90-165 to antibodies recognizing other regions of the TSHR. We also show that the development of stimulating TSHRAbs with this heterogeneous epitope or their presence at the initial screening for disease activity seems to be associated with increased responsiveness to antithyroid drug therapy. We suggest, therefore, that Mc2 chimera assays may be useful to predict the response of patients to antithyroid drug therapy.

Recent Trends in the Management of Graves' Hyperthyroidism in Japan: Opinion Survey Results, Especially on the Combination Therapy of Antithyroid Drug and Thyroid Hormone.

An opinion survey concerning the management of Graves' hyperthyroidism was conducted among the council members of the Japan Thyroid Association. The selection of 3 major treatments by 90 respondents for their patients was 98.6 +/- 4.2% for antithyroid drug (ATD), 7.8 +/- 12.6% for partial thyroidectomy and 5.2 +/- 8.1% for radioiodide. They expressed a movement away from the past trend of surgery because of postoperative complications and unsatisfactory therapeutic results, and they assumed a further reduction in the future. On the other hand, the frequency of radioiodide treatment was not considered to have decreased greatly, and they expected a slight increase in the future. Of the respondents, 65% suggested that hyperthyroidism should be completely cured even if the patient would fall into hypothyroidism. The major reasons for choosing surgery or radioiodide after ATD were the adverse effects of ATD and the age and social backgrounds of the patients. Large goiter size was the 3rd reason for surgery but was a minimal indicator for radioiodide. As for ATD treatment, none of the respondents reported the routine application of any uniform fixed-time therapy protocol. Japanese Graves' patients were shown to be less responsive to ATD than Caucasian patients. This was assumed to result at least from high iodide intake, and half of them had ordered their patients to restrict iodide intake. Furthermore, 78% of them had treated with a combined therapy of ATD and thyroid hormone. Most of them apply this for selected patients mainly to lower TSH receptor antibody activity, to better control their patients and to reduce the goiter size. All but 8 (9%) did not give T4 (or T3) after the cessation of ATD, and they felt this to be unnecessary, doubtful about the effect, unsuitable or even possible to induce recurrence. The excellent findings reported by Hashizume et al. (N Engl J Med 324: 947-953, 1991) are well known among them. However, most of them did not agree with the efficacy of the protocol to reduce TRAb or to improve the remission rate, and 90% of the respondents did not intend to apply the protocol immediately. In conclusion, the Japanese thyroidologists were shown to highly prefer ATD, and they intended to treat their patients for longer periods of time only by ATD until clinical remission is achieved. The combination therapy is widely used, but most of them do not consider it effective. The therapeutic protocol reported by Hashizume et al. was not accepted widely in Japan.

Precise determination of TSH receptor antibody activity in serum containing bovine TSH (bTSH) binding antibody by absorption using denatured bTSH or sheep FSH.

A previous report demonstrated that sera with bovine TSH (bTSH) binding antibody showed abnormally negative TSH receptor antibody (TRAb) activity in the standard TRAb assay method. The corrected TRAb activity calculated by the determination of the nonspecific binding of the labeled bTSH for each test serum [NSB(T)] resulted in positive TRAb activity. However, the precise calculation was difficult because NSB(T) level was significantly higher than the nonspecific binding in normal pool serum [NSB(N)] level. In the present experiment the determination of the TRAb activity was performed after absorption of bTSH binding antibodies by the heat-denatured bTSH to obtain more precise TRAb activity. In addition, absorption by sheep FSH (sFSH) was performed because almost all bTSH binding antibodies showed specific binding to the alpha-subunit of mammalian pituitary glycoprotein hormones in our previous study. Three days absorption of test serum using 1 mU of the heat-denatured bTSH (100 degrees C for 1 h) or 5 mU of sFSH was chosen as optimal because NSB(T) decreased remarkably to NSB(N) levels. The corrected TRAb determined after these absorptions decreased significantly compared to the corrected TRAb activity without the absorption. When the complete absorption of bTSH binding antibody was performed by the decrease of the NSB(T) level to the NSB(N) level, the TRAb activity determined by these two different absorptions was almost similar (difference was less than 10%). However, it was difficult to obtain the precise TRAb activity in the cases with extremely high bTSH binding antibody, because the NSB(T) level was higher than the NSB(N) level by the incomplete absorption of bTSH binding antibody.

Epitopes for thyroid-stimulating antibodies in Graves' sera: a possible link of heterogeneity to differences in response to antithyroid drug treatment.

To evaluate the extent and clinical relevance of epitope heterogeneity for stimulating TSH receptor antibodies (TSHRAbs), we measured the activity of IgG preparations from 66 untreated patients with Graves' disease using Chinese hamster ovary (CHO) cells transfected with wild-type human TSHR and two TSHR chimeras with residues 9-165 (Mc1 + 2) or 90-165 (Mc2) substituted by equivalent residues of the LH/CG receptor. IgG from 68% of patients lose all of the stimulating TSHRAb activity with the chimeras; IgG from 27% lose most of the activity. Thus, we show that 95% of patients have stimulating TSHRAbs that require epitopes on the N-terminal portion of the extracellular domain of the TSHR and demonstrate the importance of epitopes within residues 90-165 for the first time. Heterogeneous epitope distribution, residual activity with one or both chimeras, i.e. with epitopes other than on the N-terminus of the TSHR, occurred in 21 patients (group A). Forty-five patients with homogeneous epitope distribution (group B) had stimulating TSHRAbs that depended only on epitopes on the N-terminus of the TSHR. Patients in group A were more likely to become euthyroid during antithyroid drug therapy and to do so more quickly than group B patients. The CHO-human TSHR cell system described herein appears to be as effective as the FRTL-5 rat thyroid system in stimulating TSHRAb detection; however, the two systems appear to measure different antibody populations in about 30% of cases. Further, stimulating TSHRAb activities measured in the FRTL-5 system tend to correlate better with goiter size and 99mTc pertechnetate uptake, whereas stimulating activities measured in the CHO-human TSHR/chimera system correlate better with free T4 and T3 levels.

Heterogeneity of circulating TSH‐receptor antibodies in thyroid disease demonstrated directly by chromatography

The heterogeneity of circulating TSH-receptor antibodies (TRAb) has been demonstrated directly by affinity chromatography on the dye Remazol Yellow-GGL. The technique resolved these antibodies into discrete peaks within the general serum immunoglobulin background. Peaks were detected initially by a binding (radioreceptor) assay and then characterized by their ability to stimulate the uptake of iodine-125 into FRTL-5 cells. Thirteen subjects with high serum levels of TRAb were studied. The two hypothyroid patients each produced a single peak of TRAb activity with no ability to stimulate uptake of iodine-125 into cultured cells. The remaining 11 patients had Graves' disease; their sera produced a range of elution profiles after chromatography with TRAb activity resolved into as many as five peaks. Considerable differences were seen in the relative abilities of the resolved TRAb components to bind to receptors and to stimulate cellular uptake of iodine-125 both between and within individual samples. No two patients produced components which chromatographed in the same position on the gradients employed for elution from the dye.

Graves'DISEASE IN PREGNANCY: TSH RECEPTOR BINDING INHIBITING IMMUNOGLOBULINS AND MATERNAL AND NEONATAL THYROID FUNCTION

We studied interrelationships between maternal and neonatal thyroid function, TSH receptor binding inhibiting immunoglobulins (TBII), and dose of thionamide antithyroid drugs in 44 women with active Graves' disease presenting during 46 pregnancies, and their 48 infants. The women were treated with propylthiouracil (PTU) or carbimazole (CBZ). In 30 pregnancies (30 infants) treatment was withdrawn from 3 to 18 weeks before delivery (Group A). Drug treatment (PTU, n = 10, dose 50-400 mg/day or CBZ, n = 6, dose 5-45 mg/day) was continued throughout pregnancy and delivery in 16 pregnancies producing 18 infants (Group B). The maternal TBII at delivery was well correlated with maternal free thyroxine index (FTI) averaged over the third trimester (r = 0.603, P less than 0.001) and umbilical venous serum TBII (r = 0.940, P less than 0.001). Neonatal FTI was independently related to umbilical vein TBII (t = 2.29, P = 0.03) and maternal dose of antithyroid drug (t = -2.21, P = 0.03). Neonatal thyrotoxicosis was seen in all four infants (8% of births) of women whose TBII levels at delivery exceeded 70%. No child was born with a subnormal FTI but 7/18 infants in group B had raised TSH at birth. This was more likely to occur (P = 0.05) if maternal TBII was less than 30% (6/10) than if maternal TBII was greater than 30% (1/8). Four Group B women with FTI in the lower half of the reference range delivered infants with raised TSH compared with 3/14 (21%) women whose FTI was in the upper half of the reference range or above (P = 0.05). In pregnant women with active Graves' disease TBII levels reflect stimulatory TSH receptor antibody activity. TBII measurements are of use in the prediction of neonatal thyrotoxicosis and impaired neonatal thyroid function in infants of women treated with antithyroid drugs.

The Prognostic Application of Thyroid Volume Determination in Patients with Graves' Disease

Swelling of the thyroid gland is a common symptom in patients with Graves' disease. However, until recently there were no adequate means of measuring the thyroid volume. In this study, thyroid volume (in Graves' disease patients on antithyroid drug (ATD) therapy) was measured serially by a new ultrasound technique involving the use of a specifically programmed computer. The relationships between thyroid volume and prognosis, and between thyroid volume and serum thyroglobulin (Tg) concentration were examined. Sixty untreated patients with Graves' disease and 62 healthy subjects were included in the study. Twenty of the 60 patients with Graves' disease who had no anti-Tg antibodies underwent serial measurement of thyroid volume and serum Tg concentration during long term (18-42 months) ATD therapy. Thyroid volume in normal subjects ranged from 5.6 ml to 20.2 ml, with a mean of 12.0 +/- 4.0 ml. In patients with untreated Graves' disease, the volume ranged from 13.3 to 190.7 ml with a mean of 40.2 +/- 27.8 ml (n = 60). Thyroid volume was significantly correlated with both serum Tg concentration (n = 20, r = 0.678, p less than 0.01) and serum TSH receptor antibody activity (n = 18, r = 0.590, p less than 0.01). During ATD therapy, the thyroid volume decreased gradually in most patients. Eleven of 20 treated patients experienced remission after therapy was discontinued, and in these patients, thyroid volume was significantly smaller (p less than 0.01) than before treatment. Four patients developed hypothyroidism due to over dosage of ATD at which time thyroid volume increased in all four. In the course of therapy, even during episodes of hypothyroidism changes in serum Tg concentrations paralleled changes in thyroid volume. After 12 months of therapy, thyroid volume expressed as a percentage of the pretreatment value was significantly smaller in patients in remission (77.6 +/- 8.9%) than in those who did not show remission (92.4 +/- 11.6%). These data suggest that serial ultrasonographic measurement of thyroid volume is useful in predicting the course of hyperthyroidism in ATD-treated patients with Graves' disease.

Erratum

Abstract. Graves' disease is an autoimmune disease characterized by a course of remission and relapse. Since the introduction of antithyroid drug treatment, various parameters have been tested for their ability to predict the clinical course of a patient with Graves' disease after drug withdrawal. Nearly all these studies were retrospective and often yielded conflicting results. In a prospective multicentre study with a total of 451 patients, we investigated the significance of a variety of routine laboratory and clinical parameters for predicting a patient's clinical course. Patients who had positive TSH receptor antibodies activity at the end of therapy showed a significantly higher relapse rate than those without (P &lt; 0.001). However, the individual clinical course cannot be predicted exactly (sensitivity 0.49, specificity 0.73, N = 391). The measurement of microsomal (P = 0.99, sensitivity 0.37, specificity 0.63, N = 275) or thyroglobulin antibodies (P = 0.76, sensitivity 0.18, specificity 0.84, N = 304) at the end of antithyroid drug therapy did not show a statistically significant difference in the antibody titre between the patients of the relapse and those of the remission group. Additionally, HLA-DR typing (HLA-DR3: P = 0.37, sensitivity 0.36, specificity 0.58, N = 253) was proven to be unsuitable for predicting a patient's clinical course. Patients with abnormal suppression or an abnormal TRH test at the end of antithyroid drug therapy relapse significantly more often (P&lt; 0.001) than patients with normal suppression or normal TRH test. Patients with a large goitre also have a significantly (P&lt; 0.001) higher relapse rate than those with only a small enlargement. The sensitivity and specificity values of all these parameters, however, were too low to be useful for daily clinical decisions in the treatment of an individual patient. This is also true for the combinations of different parameters. Though the highest sensitivity value (0.94) was found for a combination of the suppression and the TRH test at the end of therapy, the very low specificity value (0.13) for this combination reduced its clinical usefulness.

Prospective multicentre study on the prediction of relapse after antithyroid drug treatment in patients with Graves' disease

Graves' disease is an autoimmune disease characterized by a course of remission and relapse. Since the introduction of antithyroid drug treatment, various parameters have been tested for their ability to predict the clinical course of a patient with Graves' disease after drug withdrawal. Nearly all these studies were retrospective [corrected] and often yielded conflicting results. In a prospective multicentre study with a total of 451 patients, we investigated the significance of a variety of routine laboratory and clinical parameters for predicting a patient's clinical course. Patients who had positive TSH receptor antibodies activity at the end of therapy showed a significantly higher relapse rate than those without (P less than 0.001). However, the individual clinical course cannot be predicted exactly (sensitivity 0.49, specificity 0.73, N = 391). The measurement of microsomal (P = 0.99, sensitivity 0.37, specificity 0.63, N = 275) or thyroglobulin antibodies (P = 0.76, sensitivity 0.18, specificity 0.84, N = 304) at the end of antithyroid drug therapy did not show a statistically significant difference in the antibody titre between the patients of the relapse and those of the remission group. Additionally, HLA-DR typing (HLA-DR3: P = 0.37, sensitivity 0.36, specificity 0.58, N = 253) was proven to be unsuitable for predicting a patient's clinical course. Patients with abnormal suppression or an abnormal TRH test at the end of antithyroid drug therapy relapse significantly more often (P less than 0.001) than patients with normal suppression or normal TRH test. Patients with a large goitre also have a significantly (P less than 0.001) higher relapse rate than those with only a small enlargement. The sensitivity and specificity values of all these parameters, however, were too low to be useful for daily clinical decisions in the treatment of an individual patient. This is also true for the combinations of different parameters. Though the highest sensitivity value (0.94) was found for a combination of the suppression and the TRH test at the end of therapy, the very low specificity value (0.13) for this combination reduced its clinical usefulness.

Determination of thyroid volume using computerized ultrasonography and its clinical application

A new method for determining thyroid gland volume was developed by means of computerized ultrasonography. A maximum area of the thyroid (S) was obtained from coronal sections and a maximum thickness (C) was obtained from sagittal sections. The thyroid volume was then calculated by SXC. The volume of phantoms and pig thyroids obtained by this method was identical with the actual volume. The thyroid volume in this method correlated well with the estimated volume in patients with Graves' disease undergoing thyroidectomy (r = 0.954). The measurement was then performed in 56 healthy subjects (male 28, female 28, age 15-68 y.o.) and 126 patients with thyroid diseases. The thyroid volume in healthy men was significantly larger than that in women (18.4 +/- 6.1 ml vs 13.9 +/- 4.9 ml, Mean +/- SD, p less than 0.01). The thyroid volume in normal subjects correlated with body height, body weight or body surface area (p less than 0.01), which may explain the sex differences. An attempt was made to calculate the prospective thyroid volume (Y ml) from body height as follows; Y = 0.425 X - 52.8, X; body height (cm). Four out of thirty patients with untreated Graves' disease had a gland volume of the normal range, but in all patients the thyroid volume was larger than the prospective volume. The thyroid volume and the rate of volume increase (determined thyroid volume/calculated prospective volume) were correlated with the serum levels of T3, T4 concentration in the untreated stage. The volume and the rate of volume increase did not correlate with serum TSH receptor antibody activity. The thyroid volume in patients with Graves' disease who had been in remission (33.0 +/- 13.5 ml) was significantly smaller than that in untreated patients (51.8 +/- 24.4 ml, p less than 0.02). These findings indicate that the present method is reliable and clinically useful for the investigation of thyroid diseases.

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.

A receptor assay for the measurement of TSH receptor antibodies in unextracted serum.

A receptor assay for TSH receptor antibodies is described in which unextracted serum, detergent solubilised TSH receptors and 125I-labelled TSH are used. The assay was rapid and reproducible with coefficients of inter-assay variation of 12.3%, 2.1 and 2.6% at mean inhibition of TSH binding values of 11, 53, and 79 respectively. Assay sensitivity could be increased by reducing the volume of receptors used but some increase in the scatter of values obtained with individual normal sera was also observed. Comparison of human and porcine TSH receptor preparations indicated that porcine tissue gave greater sensitivity. Analysis of different groups of patients and normal subjects (n = 21) showed the absence of detectable TSH receptor antibody activity in 16 patients with rheumatoid arthritis, 10 with multinodular goitre and 12 with Hashimoto's disease. However the antibody was readily detectable in 28 out of 28 Graves' patients (treated and untreated) who were hyperthyroid at the time of assay.

Ratio of serum triiodothyronine to thyroxine and the prognosis of triiodothyronine-predominant Graves' disease.

Triiodothyronine (T3)-predominant Graves' disease is characterized by persistently high serum T3 level, normal serum thyroxine (T4) level, and high (greater than 20) serum T3/T4 ratio (nanograms/micrograms) during thionamide drug therapy. We studied the clinical course of 30 patients with T3-predominant Graves' disease. After receiving drug therapy for 1 to 4 years, 27 patients with T3-predominant Graves' disease had relapses, whereas only 9 control patients with Graves' disease whose serum T3/T4 ratio had become persistently normal (less than 20) had relapses. The T3-predominant patients had greater serum TSH receptor antibody activity, thyroid T4 5'-deiodinase activity, and decreased T3 content of thyroglobulin when compared with the control patients. Our findings show that patients with T3-predominant Graves' disease are unlikely to have a long-term remission with drug therapy. The cause of high serum T3/T4 ratio is due, in part, to the more active thyroid T4 5'-deiodinase that may be mediated by high levels of Graves' immunoglobulin.