Evidence for an effect of antithyroid drugs on the natural history of Graves' disease

Antithyroid Drug Treatment in Graves' Disease

Graves' disease is associated with thyrotropin (TSH) receptor stimulating antibody, for which there is no therapeutic agent. This disease is currently treated through inhibition of thyroid hormone synthesis or destruction of the thyroid gland. Recurrence after antithyroid drug (ATD) treatment is common. Recent studies have shown that the longer is the duration of use of ATD, the higher is the remission rate. Considering the relationship between clinical outcomes and iodine intake, recurrence of Graves' disease is more common in iodine-deficient areas than in iodine-sufficient areas. Iodine restriction in an iodine-excessive area does not improve the effectiveness of ATD or increase remission rates. Recently, Danish and Korean nationwide studies noted significantly higher prevalence of birth defects in newborns exposed to ATD during the first trimester compared to that of those who did not have such exposure. The prevalence of birth defects was lowest when propylthiouracil (PTU) was used and decreased by only 0.15% when methimazole was changed to PTU in the first trimester. Therefore, it is best not to use ATD in the first trimester or to change to PTU before pregnancy.

Effect of Addition of Thyroxine in the Treatment of Graves' Disease: A Systematic Review

Graves' disease is the most common cause of hyperthyroidism. Antithyroid drugs, radioiodine ablation, and surgery are the main treatments. Research has demonstrated that adding thyroxine to antithyroid therapy can improve the remission rate, and many similar studies have been conducted subsequently. The purpose of this systematic review was to investigate whether adding thyroxine to various treatments for Graves' disease has a clinical benefit in remission/relapse rate, stable thyroid function, occurrence of Graves' ophthalmopathy, etc. A total of 27 studies were included, and the risk of research bias was moderate to high. We discuss the role of thyroxine both in pharmacological and non-pharmacological therapeutic regimens. Overall, the available evidence does not support the indiscriminate addition of thyroxine to various treatments for Graves' disease, especially in combination with oral antithyroid drugs. Further clinical studies are required to explore the indications of thyroxine addition in the treatment of Graves' disease.

Thymic lymphoid hyperplasia with Graves' disease in a 28-year-old female: a case report

Thymic lymphoid hyperplasia with Graves' disease (GD) is not uncommon in adults. Generally, cases are newly diagnosed with GD when they refer to the department of endocrinology in hospital, and an anterior mediastinal mass is found on a computed tomography scan by accident. Almost half of them receive thymectomy due to the concern about thymoma or thymic carcinoma. In the past literature, an enlarged thymus can gradually shrink after treatment of antithyroid drugs. In this paper, a 28-year-old woman presented to our hospital with a 11-month history of dizziness, left hand convulsion and paralysis, without chest pain, difficulty swallowing, dyspnea. Chest computed tomography revealed an anterior mediastinal mass without obvious nodules. However, in this case, the mass did not shrink obviously after regularly taking antithyroid drugs. In order to figure out the diagnosis of the mass, we performed a thoracoscopic thymic resection, and the pathologic result was thymic lymphoid hyperplasia. There is no thymus gland tissue left on a repeated CT scan four months later after surgery. In this report, we discuss the optimal therapeutic strategy for this rare case. In conclusion, if an anterior mediastinal mass in GD patients did not shrink obviously upon treatment of antithyroid drugs, minimally invasive surgery should be taken into consideration seriously to exclude the possibility of malignancy.

Graves' Disease and the Post-partum Period: An Intriguing Relationship

The post-partum period is an immunologically peculiar period in a woman's life. Indeed, most of the pregnancy-related immune changes gradually revert in the 12 months following delivery. Although the post-partum period has long been identified as a period of aggravation of autoimmune thyroid diseases, most of the currently available studies took into account the relationship between post-partum and autoimmune thyroiditis. More recently, the potential repercussions of the post-partum period on Graves' disease were also taken into account. The present mini review will briefly overview the most recent advances in our knowledge of the immunology of the post-partum period in relation with the potential repercussions on the clinical course of Graves' disease. Moreover, some peculiar aspects of post-partum Graves' disease in terms of clinical and biochemical presentation, diagnostic challenges, and specific therapeutic considerations also taking into account the recommendation of the latest clinical guidelines on the management of thyroid diseases in pregnancy will be overviewed.

Post-partum and non-post-partum relapsing Graves' hyperthyroidism display different response to anti-thyroid drugs

DESIGN

Graves' disease (GD) patients in remission after a full course of methimazole (MMI) therapy are at risk for a relapse of hyperthyroidism during the post-partum (PP) period, but whether this relapse may display any peculiarity is still unknown. Aim of this study was to compare GD patients undergoing a relapse of hyperthyroidism either in the PP period or not.

METHODS

We retrospectively evaluated forty-three GD female patients in their childbearing age who experienced a relapse of hyperthyroidism. Eighteen of them relapsed in the PP period (i.e. within 12 months after delivery, PP group); the remaining 25 relapsed elsewhere during life (NPP group).

RESULTS

Age at relapse, thyroid volume, thyroid function tests, TRAb titers, smoking habit, presence and degree of orbitopathy and duration of methimazole (MMI) treatment did not differ in the two groups. However, the remission rate was much greater (79%) in the PP as compared with the NPP (32%) group (P = 0.002). A significant reduction in TRAb levels occurred at 12-month MMI treatment in the PP (F = 9.016; P = 0.001), but not in the NPP group (F = 2.433; NS). At 12 months, the PP group had significantly lower mean TRAb levels (0.6 ± 1.1 U/L and 4.5 ± 4.7 U/L in the PP and the NPP group, respectively; P = 0.029).

CONCLUSIONS

Relapsing Graves' hyperthyroidism in the PP period is more prone to undergo a remission after a second course of MMI treatment. In these patients, a conservative therapeutic approach is more appropriate.

Relation between therapy options for Graves' disease and the course of Graves' ophthalmopathy: a systematic review and meta-analysis

BACKGROUND

The relation between therapy options for Graves' disease (GD) and the course of Graves' ophthalmopathy (GO) are still controversial. Our aim was to compare the occurrence of development or worsening of GO in patients who were treated with antithyroid drugs (ATDs) or radioactive iodine (RAI) or thyroidectomy (TX).

METHODS

We conducted a comprehensive search of the Embase and PubMed database. Odds ratio (OR) was used as a measure of the effect of therapy options for GD on the risk of development or worsening of GO. The analysis was further stratified by factors that could affect the treatment effects.

RESULTS

Nine trials involving 1773 patients were included. RAI therapy showed a significant effect on the risk of development or worsening GO compared with ATD (OR 2.25; 95 % CI 1.61-3.14; P < 0.00001). Glucocorticoid prophylaxis was effective in preventing GO development or worsening (0.40; 0.23-0.68; P = 0.002); especially for patients with preexisting GO (0.41; 0.23-0.73; P = 0.002). At 3 months, showed GO to be improved in 17 TX and 21 total thyroid ablation (TTA) patients, with no significant difference between the two groups; between 6 and 12 months, TTA did show significant beneficial effect on the improvement of GO (6.02; 2.80-12.96; P < 0.00001); GO was found to be inactive in a significantly higher percentage of patients in the TTA (2.17; 1.04-4.52; P = 0.04).

CONCLUSION

Radioiodine therapy is a significant risk factor for development or worsening of GO in GD. But GO progression can be prevented by prophylactic glucocorticoids in patients with preexisting GO. Compared with TX alone, TTA induces an earlier and steadier GO improvement in patients with mild to moderate-severe and active GO. Whether this is sufficient to offer TTA to patients needs further investigation.

Radioiodine therapy versus antithyroid drugs in Graves' disease: a meta-analysis of randomized controlled trials

OBJECTIVE:

This meta-analysis was performed to compare radioiodine therapy with antithyroid drugs in terms of clinical outcomes, including development or worsening of ophthalmopathy, hyperthyroid cure rate, hypothyroidism, relapse rate and adverse events.

METHODS:

Randomized controlled trials (RCTs) published in PubMed, Embase, Web of Science, SinoMed and National Knowledge Infrastructure, China, were systematically reviewed to compare the effects of radioiodine therapy with antithyroid drugs in patients with Graves' disease. Results were expressed as risk ratio with 95% confidence intervals (CIs) and weighted mean differences with 95% CIs. Pooled estimates were performed using a fixed-effects model or random-effects model, depending on the heterogeneity among studies.

RESULTS:

17 RCTs involving 4024 patients met the inclusion criteria and were included. Results showed that radioiodine treatment has increased risk in new ophthalmopathy, development or worsening of ophthalmopathy and hypothyroidism. Whereas, compared with antithyroid drugs, radioiodine treatment seems to have a higher hyperthyroid cure rate, lower recurrence rate and lower incidence of adverse events.

CONCLUSION:

Radioiodine therapy is associated with a higher hyperthyroid cure rate and lower relapse rate compared with antithyroid drugs. However, it also increases the risk of ophthalmopathy and hypothyroidism.

ADVANCES IN KNOWLEDGE:

Considering that antithyroid drug treatment can be associated with unsatisfactory control of hyperthyroidism, we would recommend radioiodine therapy as the treatment of choice for patients with Graves' disease.

Raman and DFT study of methimazole chemisorbed on gold colloidal nanoparticles

The SERS/DFT study of methimazole chemisorbed on Au nanoparticles paves the way for the use of these nanohybrids in biomedicine.

Thymic hyperplasia in patients with Graves' disease

BACKGROUND

Graves' disease (GD) is commonly associated with other autoimmune conditions, and there is also a rare but well documented association between GD and thymic hyperplasia (TH). It is hard to say the real frequency of this latter association because most cases remain asymptomatic and are consequently not thoroughly investigated.

MATERIALS AND METHODS

We reviewed the literature on GD-related thymus enlargement and found 107 cases published to date. Thymic cancer was only documented in four patients, while the majority of cases were diagnosed as TH. The causative mechanisms behind TH associated with GD have yet to be fully elucidated. Several studies support the hypothesis of a TSH receptor antibody (TRAb) mediating thymic enlargement.

RESULTS

We report on a female GD patient with an incidentally discovered anterior mediastinal mass. Our case is not consistent with the hypothesis of a TRAb-mediated mechanism because the thymus reached its largest volume at the onset of GD and shrank during remission of GD under medical treatment, despite persistently positive TRAb levels.

CONCLUSION

We support the hypothesis that two different pathogenic mechanisms might be responsible for thymus enlargement: thymic cortical tissue expansion seems to be due to a hyperthyroid state, while lymphoid hyperplasia appears to correlate with immune abnormalities underlying GD.

An update on the medical treatment of Graves' hyperthyroidism

Medical treatment of Graves' hyperthyroidism is based on the use of thionamides; namely, methimazole and propylthiouracil. In the past, methimazole was preferred by European endocrinologists, whereas propylthiouracil was the first choice for the majority of their North American colleagues. However, because of the recent definition of a better side-effect profile, methimazole is nowadays the first choice world while. Although thionamides are quite effective for the short-term control of Graves' hyperthyroidism, a relatively high proportion of patients relapses after thionamide withdrawal. Other possible medical treatments, include iodine and compounds containing iodine, perchlorate, lithium (as an adjuvant in patients undergoing radioiodine therapy), β-adrenergic antagonists, glucocorticoids, and some new molecules still under investigation. Management of Graves' hyperthyroidism using thionamides as well as the other available medical treatments is here reviewed in detail, with a special mention of situations such as pregnancy and lactation, as well as neonatal and fetal thyrotoxicosis.

Increase of interferon-γ inducible CXCL9 and CXCL11 serum levels in patients with active Graves' disease and modulation by methimazole therapy

BACKGROUND

Chemokine (C-X-C motif) ligand (CXCL)9 and CXCL11 play an important role in the initial phases of autoimmune thyroiditis (AT); however, their serum levels in patients with Graves' disease (GD) have never been evaluated in relation to thyroid function and treatment.

METHODS

To evaluate CXCL9 and CXCL11 serum levels in GD and to relate these parameters to the clinical phenotype, we measured CXCL9 and CXCL11 serum levels in 91 GD patients; 91 AT, 34 nontoxic multinodular goiters (MNGs), 31 toxic nodular goiters (TNGs), respectively; and 91 healthy controls (age- and sex-matched).

RESULTS

Mean CXCL9 and CXCL11 levels were higher in GD in comparison with controls, euthyroid AT, MNG, or TNG (p < 0.05, ANOVA; CXCL9: 274 ± 265, 76 ± 33, 132 ± 78, 87 ± 48, and 112 ± 56  pg/mL; CXCL11: 140 ± 92, 64 ± 20, 108 ± 48, 76 ± 33, 91 ± 41 pg/mL, respectively). Hyperthyroid GD patients had significantly higher CXCL9 or CXCL11 than euthyroid or hypothyroid GD patients. GD patients with untreated hyperthyroidism had higher CXCL9 or CXCL11 than hyperthyroid or euthyroid GD patients under methimazole (MMI) treatment. Comparable CXCL9 and CXCL11 levels were observed in newly diagnosed untreated hyperthyroid GD versus untreated patients with relapse of hyperthyroidism after a previous MMI course.

CONCLUSIONS

Serum CXCL9 and CXCL11 levels are associated with the active phase of GD both in newly diagnosed and relapsing hyperthyroid patients. The reduction of serum CXCL9 and CXCL11 levels in treated patients with GD may be related to the immunomodulatory effects of MMI.

The effect of B cell depletion therapy on anti-TSH receptor antibodies and clinical outcome in glucocorticoid-refractory Graves' orbitopathy

OBJECTIVE

This case series documents the response of nine individuals with glucocorticoid-refractory Graves' orbitopathy (GO) to B cell depletion therapy with rituximab (RTX).

CONTEXT

Graves' disease (GD) is one of the commonest autoimmune conditions and is frequently associated with inflammatory changes around the eyes (GO). GO frequently results in significant functional visual impairment, and in the most severe cases, it can result in permanent loss of sight. RTX is a therapeutic monoclonal antibody, which targets cell-surface CD-20, resulting in depletion of circulating B lymphocytes. It has been found to be useful for the treatment of a number of autoimmune conditions including, in preliminary studies, GO.

DESIGN AND PATIENTS

We have treated nine individuals (1 male, 8 female, age range 37-87 years) with glucocorticoid-resistant GO with RTX since 2008. RTX was administered in divided doses at fortnightly intervals, following 500 mg IV methylprednisolone pretreatment.

MEASUREMENTS

Each patient underwent thorough assessment before and after RTX therapy, including thyroid function tests, B cell counts, thyroid autoantibody levels and detailed clinical assessment according to EUGOGO standard protocols. All patients have now been followed up for 16 months or more.

RESULTS

There was a significant reduction in thyrotropin receptor binding inhibitory immunoglobulin (TBII) levels in all patients following RTX treatment and a reduction in the clinical activity score (CAS) was seen in all cases. We also report striking improvement in pretibial thyroid dermopathy in one patient following RTX.

CONCLUSIONS

This case series adds to the growing literature demonstrating that RTX, administered in our patients with concomitant methylprednisolone, is safe and clinically effective in the treatment of active, moderate to severe and sight-threatening GO. Randomized controlled trials are now needed to confirm the efficacy of RTX for GO.

Radioiodine therapy in benign thyroid diseases: effects, side effects, and factors affecting therapeutic outcome

Radioiodine ((131)I) therapy of benign thyroid diseases was introduced 70 yr ago, and the patients treated since then are probably numbered in the millions. Fifty to 90% of hyperthyroid patients are cured within 1 yr after (131)I therapy. With longer follow-up, permanent hypothyroidism seems inevitable in Graves' disease, whereas this risk is much lower when treating toxic nodular goiter. The side effect causing most concern is the potential induction of ophthalmopathy in predisposed individuals. The response to (131)I therapy is to some extent related to the radiation dose. However, calculation of an exact thyroid dose is error-prone due to imprecise measurement of the (131)I biokinetics, and the importance of internal dosimetric factors, such as the thyroid follicle size, is probably underestimated. Besides these obstacles, several potential confounders interfere with the efficacy of (131)I therapy, and they may even interact mutually and counteract each other. Numerous studies have evaluated the effect of (131)I therapy, but results have been conflicting due to differences in design, sample size, patient selection, and dose calculation. It seems clear that no single factor reliably predicts the outcome from (131)I therapy. The individual radiosensitivity, still poorly defined and impossible to quantify, may be a major determinant of the outcome from (131)I therapy. Above all, the impact of (131)I therapy relies on the iodine-concentrating ability of the thyroid gland. The thyroid (131)I uptake (or retention) can be stimulated in several ways, including dietary iodine restriction and use of lithium. In particular, recombinant human thyrotropin has gained interest because this compound significantly amplifies the effect of (131)I therapy in patients with nontoxic nodular goiter.

Hyperthyroidism

Hyperthyroidism is a pathological syndrome in which tissue is exposed to excessive amounts of circulating thyroid hormone. The most common cause of this syndrome is Graves' disease, followed by toxic multinodular goitre, and solitary hyperfunctioning nodules. Autoimmune postpartum and subacute thyroiditis, tumors that secrete thyrotropin, and drug-induced thyroid dysfunction, are also important causes.

An adolescent with a mediastinal mass, diagnosed with Graves disease and thymic hyperplasia

Graves disease is an autoimmune disorder characterized by thyroid enlargement and hyperthyroidism. Thyrotropin receptor (TSHR) autoantibodies bind the TSHR on the membrane of thyroid follicular cells and stimulate cell proliferation and thyroid-hormone synthesis. TSHR has also been identified in extrathyroidal organs, including the human thymus. Thus far, radiologically detectable thymic enlargement has only been reported in adults with Graves disease. We present here the case of a child with Graves disease and significant thymic hyperplasia. L. K. was a 15-year-old girl evaluated for cough and dyspnea on exertion. A chest radiograph was obtained, and it revealed a widened superior mediastinum. A computed-tomography scan of her chest identified a mass in the anterior mediastinum without associated lymphadenopathy. Because of these radiologic findings and her weight loss, she was referred to the oncology service; a biopsy of the mediastinal mass was obtained and revealed thymic reactive hyperplasia. Because of persistent tachycardia, thyroid studies were obtained, and the diagnosis of Graves disease was established. The child's physical examination revealed a minimally enlarged thyroid gland and no exophthalmos. One month after medical treatment was initiated, a repeat computed-tomography scan of her chest identified significantly reduced thymic size. To our knowledge, this is the first pediatric patient reported with Graves disease and significant thymic enlargement. Considering the diagnosis of Graves disease for a child with an anterior mediastinal mass and without the typical physical findings of autoimmune hyperthyroidism (goiter, exophthalmos) may prevent unnecessary diagnostic studies and their associated financial and emotional costs.

Thyroid peroxidase forms thionamide-sensitive homodimers: relevance for immunomodulation of thyroid autoimmunity

Thyroid peroxidase (TPO) is the key enzyme in thyroid hormone production and a universal autoantigen in Graves’ and other autoimmune thyroid diseases. We wished to explore the expression of TPO and whether it was affected by thionamide antithyroid drugs. We studied recombinant TPO, stably expressed by a Chinese hamster ovary cell line (CHO-TPO) and transiently expressed TPO-enhanced green fluorescent protein (eGFP) and -FLAG fusion proteins. Immunoblotting of CHO-TPO cell extracts showed high-molecular weight (HMW) TPO isoforms that were resistant to reduction, as well as 110 kDa monomeric TPO. Co-immunoprecipitation and enzyme-linked-immunosorbent assay (ELISA) binding studies of FLAG- and eGFP-tagged TPO demonstrated TPO dimerisation. CHO-TPO cells cultured in methimazole (MMI) for 10 days showed a significant reduction in HMW-TPO isoforms at MMI concentrations of 1 µM and above (p < 0.01), whereas monomeric TPO expression was unchanged. We observed a similar reduction in HMW-TPO in CHO-TPO cells cultured in propylthiouracil (10 µM and above). Binding of Graves’ disease patient sera and TPO-Fabs to enzymatically active TPO that was captured onto solid phase was not abrogated by MMI. The cellular localisation of TPO in CHO-TPO cells was unchanged by MMI treatment. Our demonstration of homodimeric TPO and the reduction in HMW-TPO isoforms during thionamide treatment of CHO-TPO cells shows, for the first time, an effect of thionamides on TPO structure. This suggests a structural correlate to the effect of thionamides on TPO enzymatic activity and opens up a novel potential mechanism for thionamide immunomodulation of autoimmune thyroid disease.

Lack of effect of methimazole on dendritic cell (DC) function and DC-induced Graves' hyperthyroidism in mice

In addition to the biochemical inhibition of thyroid hormone synthesis, antithyroid drugs including methimazole (MMI) may have immunosuppressive effect through inhibition of major histocompatibility complex (MHC) class I and II expressions on non-professional (thyrocytes) and professional (macrophages and B cells) antigen presenting cells (APCs). Dendritic cells (DCs) are another professional APCs and very likely play the most important role in the primary immune response. Therefore, we focused in this study on evaluating the effect of MMI on DC function in mice. Bone marrow cells cultured with granulocyte macrophage colony stimulating factor and interleukin (IL)-4 expressed high levels of CD11c and moderate levels of MHC class II, both of which are widely used markers for DCs. In vitro incubation of this DC-containing cell population with 10(- 6)-10(- 4) M MMI for 2 days did not change basal- and maturation signal (adenoviral infection and lipopolysaccharide)-induced levels of the cell surface marker expressions such as MHC class I and II, CD86, CD40 and DEC205, and of proinflammatory cytokine IL-6 release. Further we found that treatment of the DC-containing cell population with MMI did not influence the incidence of Graves' hyperthyroidism and anti-thyrotropin receptor (TSHR) antibody titers in a mouse Graves' model we have recently established with DCs infected with adenovirus expressing the TSHR A subunit. Although we cannot completely exclude immunosuppressive effect of MMI on other immune cells, our data indicate that DCs do not appear to be the primary target for the immunosuppressive effect of MMI.

Role of chemokines in endocrine autoimmune diseases

Chemokines are a group of peptides of low molecular weight that induce the chemotaxis of different leukocyte subtypes. The major function of chemokines is the recruitment of leukocytes to inflammation sites, but they also play a role in tumoral growth, angiogenesis, and organ sclerosis. In the last few years, experimental evidence accumulated supporting the concept that interferon-gamma (IFN-gamma) inducible chemokines (CXCL9, CXCL10, and CXCL11) and their receptor, CXCR3, play an important role in the initial stage of autoimmune disorders involving endocrine glands. The fact that, after IFN-gamma stimulation, endocrine epithelial cells secrete CXCL10, which in turn recruits type 1 T helper lymphocytes expressing CXCR3 and secreting IFN-gamma, thus perpetuating autoimmune inflammation, strongly supports the concept that chemokines play an important role in endocrine autoimmunity. This article reviews the recent literature including basic science, animal models, and clinical studies, regarding the role of these chemokines in autoimmune endocrine diseases. The potential clinical applications of assaying the serum levels of CXCL10 and the value of such measurements are reviewed. Clinical studies addressing the issue of a role for serum CXCL10 measurement in Graves' disease, Graves' ophthalmopathy, chronic autoimmune thyroiditis, type 1 diabetes mellitus, and Addison's disease have been considered. The principal aim was to propose that chemokines, and in particular CXCL10, should no longer be considered as belonging exclusively to basic science, but rather should be used for providing new insights in the clinical management of patients with endocrine autoimmune diseases.

Continued suppression of serum TSH level may be attributed to TSH receptor antibody activity as well as the severity of thyrotoxicosis and the time to recovery of thyroid hormone in treated euthyroid Graves' patients

The cause of continued suppression of serum thyroid-stimulating hormone (TSH) levels during antithyroid drug therapy in some Graves' patients is unclear. Recently, there has been a notable explanation involving the direct inhibition of TSH receptor antibody (TRAb) on TSH secretion in the pituitary gland. The purpose of this study is to verify the relation between TRAb or other clinical parameters and the continued suppression of serum TSH level during antithyroid drug therapy in patients with Graves' disease. We reviewed the medical records of patients with Graves' disease between 1995 and 2002 at Samsung Medical Center. We selected 167 Graves' patients who had been euthyroid for at least 12 months after recovery of serum T3 and T4 levels during the antithyroid drug therapy. We analyzed the correlation of the interval until recovery of serum TSH with the pretreatment clinical parameters. We compared the recovery rates of suppressed TSH levels between pretreatment thyrotrophin-binding inhibitory immunoglobulin (TBII)-positive (>15%) and TBII-negative patients. We also compared the clinical parameters between two groups at the time of diagnosis and after recovery of thyroid hormone. Pretreatment serum T3 level, (131)I uptake, TBII activity, and the time to recovery of T3 or T4/free T4 level showed significant positive correlations with the interval until recovery of serum TSH level ( p < 0.05). Recovery rates of serum TSH levels at 3 months after recovery of thyroid hormone were significantly lower in pretreatment TBII-positive patients than those in TBII-negative patients ( p < 0.01). Serum TSH levels were significantly lower in TBII-positive patients at 3 months after recovery of thyroid hormone ( p < 0.05). TBII activities inversely correlated only with serum TSH levels at 3months after recovery of thyroid hormone ( p < 0.001). In conclusion, continued suppression of serum TSH level may be attributed to TRAb activity as well as the pretreatment severity of thyrotoxicosis and the time to recovery of thyroid hormone in patients with Graves' disease during antithyroid drug therapy.

Serum levels of the interferon-γ-inducible α chemokine CXCL10 in patients with active Graves' disease, and modulation by methimazole therapy and thyroidectomy

Background

The interferon-γ-inducible chemokine CXCL10 is highly expressed in infiltrating inflammatory cells, and in thyrocytes in patients with Graves' disease. The aim of this study was to measure serum levels of CXCL10 in relation to thyroid function and treatment.

Methods

Serum levels of CXCL10 were measured in 22 patients with Graves' disease when hyperthyroid, when euthyroid under methimazole therapy, and 3 days after near-total thyroidectomy. They were compared with levels in three groups of age- and sex-matched controls: 44 subjects with no thyroid disorder, 44 patients with euthyroid autoimmune thyroiditis and 20 with toxic nodular goitre.

Results

Basal serum levels of CXCL10 in patients with Graves' disease were higher than levels in patients with toxic nodular goitre or no thyroid disorder, and similar to levels in patients with autoimmune thyroiditis (mean(s.d.) 167(121), 100(24), 78(46) and 142(107) pg/ml respectively; P &lt; 0·010). Among patients with Graves' disease, serum levels of CXCL10 were significantly higher in those aged over 50 years (P = 0·010), with a hypoechoic pattern at thyroid ultrasonography (P &lt; 0·001) or with hypervascularity (P = 0·001). CXCL10 levels in patients with Graves' disease decreased significantly when euthyroidism was achieved by methimazole therapy (P &lt; 0·010), and a further decrease was observed after thyroidectomy (P &lt; 0·010).

Conclusion

Serum levels of CXCL10 are higher in newly diagnosed hyperthyroid patients with Graves' disease than in those with toxic nodular goitre, and decrease when euthyroidism is achieved with antithyroid therapy. This high level may be related to the active inflammatory phase of Graves' disease. A further reduction of CXCL10 levels after thyroidectomy indicates that it is produced mainly in the thyroid in patients with autoimmune thyroid disease.

Increase of interferon-gamma-inducible CXC chemokine CXCL10 serum levels in patients with active Graves' disease, and modulation by methimazole therapy

BACKGROUND

CXCL10 plays an important role in the initial phases of Graves' disease (GD) and autoimmune thyroiditis (AT); however, until now, CXCL10 serum levels (sCXCL10) in patients with GD have never been evaluated in relation to thyroid function and treatment.

OBJECTIVE

To evaluate sCXCL10 in GD.

DESIGN

Cross-sectional.

PATIENTS

One hundred and three GD, 164 AT, 20 nontoxic multinodular goitre (NTMNG), 16 toxic nodular goitre (TNG) patients and 70 healthy controls (age- and sex-matched).

MEASUREMENTS

We measured sCXCL10 in patients and controls, to relate this parameter to the clinical phenotype.

RESULTS

Mean sCXCL10 in GD and AT patients were comparable (122+/-81 and 133+/-102 pg/ml) and significantly higher (P<0.01) than in controls or NTMNG patients (73+/- 32 and 76+/- 25 pg/ml, respectively). Hyperthyroid GD had significantly higher sCXCL10 than euthyroid or hypothyroid GD (145+/- 92, 107+/- 56 and 105+/- 46 pg/ml, respectively; P=0.01). GD patients with untreated hyperthyroidism had higher sCXCL10 than hyperthyroid or euthyroid GD patients under methimazole (MMI) treatment (166+/-125, 124+/- 41 and 94+/- 35 pg/ml, respectively; P=0.006). Comparable sCXCL10 levels were observed in newly diagnosed untreated hyperthyroid GD patients with respect to untreated patients with relapse of hyperthyroidism after a previous MMI course (176+/-125, 155+/- 97 pg/ml, respectively). GD had similar sCXCL10 to AT and higher than TNG patients or controls (all age- and sex-matched) (144+/- 81, 149+/- 114, 101+/- 27 and 86+/- 44 pg/ml, respectively; P=0.02).

CONCLUSIONS

sCXCL10 is associated with the active phase of GD in both newly diagnosed and relapsing hyperthyroid patients. The reduction in sCXCL10 in treated patients with GD may be related to the immunomodulatory effects of MMI.

Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine

OBJECTIVE

To investigate the long-term effects of continuous methimazole (MMI) therapy.

DESIGN AND METHODS

Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. Within one year after discontinuation of MMI, hyperthyroidism recurred in 104 patients. They were randomized into 2 groups for continuous antithyroid and radioiodine treatment. Numbers of occurrences of thyroid dysfunction and total costs of management were assessed during 10 years of follow-up. At the end of the study, 26 patients were still on continuous MMI (group 1), and of 41 radioiodine-treated patients (group 2), 16 were euthyroid and 25 became hypothyroid. Serum thyroid and lipid profiles, bone mineral density, and echocardiography data were obtained.

RESULTS

There was no significant difference in age, sex, duration of symptoms and thyroid function between the two groups. No serious complications occurred in any of the patients. The cost of treatment was lower in group 1 than in group 2. At the end of 10 years, goiter rate was greater and antithyroperoxidase antibody concentration was higher in group 1 than in group 2. Serum cholesterol and low density lipoprotein-cholesterol concentrations were increased in group 2 as compared with group 1; relative risks were 1.8 (1.12-2.95, P<0.02) and 1.6 (1.09-2.34, P<0.02) respectively. Bone mineral density and echocardiographic measurements were not different between the two groups.

CONCLUSION

Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.

Hyperthyroidism: advantages and disadvantages of medical therapy

The most common causes of hyperthyroidism are Graves' disease, toxic nodular goiter, and iodine-induced hyperthyroidism. Hyperthyroidism can be treated medically with antithyroid drugs or radioactive iodine, or surgically. Multiple clinical factors must be weighed when choosing a treatment modality. All of the available forms of therapy have advantages and disadvantages, and treatment choices must be individualized.

Thymic hyperplasia presenting as anterior mediastinal mass in 2 patients with Graves disease

Graves disease is an autoimmune thyroid condition characterized by the production of autoantibodies against the thyrotropin receptor. The autoantibodies mimic the effect of the hormone on thyroid cells, which stimulates autonomous production of thyroxine and triiodothyronine. It has been hypothesized that cross-reactivity of autoantibodies may result in Graves ophthalmopathy and dermopathy. A seldom-recognized feature of Graves disease is thymic hyperplasia. We report 2 patients with Graves disease and incidentally discovered anterior mediastinal masses presumed to be thymic hyperplasia. In both cases, these masses regressed spontaneously after treatment of hyperthyroidism.

Methimazole as an antioxidant and immunomodulator in thyroid cells: mechanisms involving interferon-gamma signaling and H(2)O(2) scavenging

The antithyroid drug, methimazole (MMI) is used to treat patients with Graves' hyperthyroidism. The major action of MMI is to inhibit synthesis of thyroid hormone in the thyroid gland. However, MMI also has antioxidant and immunomodulatory effects on thyrocytes and/or immune cells. This study identifies novel antioxidant and immunomodulatory effects of MMI involving the interferon-gamma (IFN-gamma) signaling pathway in thyroid cells. MMI inhibits transcription of the intercellular adhesion molecule-1 (ICAM-1) gene by modulating the function of transcription factor STAT1 (signal transducer and activator of transcription 1), which binds to the IFN-gamma activated site of the ICAM-1 promoter. Furthermore, MMI rapidly eliminates H(2)O(2) produced by IFN-gamma treatment in thyroid cells and thus inhibits the H(2)O(2)-mediated phosphorylation of tyrosine 701 in STAT1. MMI also eliminates H(2)O(2) in vitro. MMI facilitates electron transfer from NADPH to H(2)O(2) using thioredoxin or glutathione, fulfilling a role similar to peroxiredoxin or glutathione peroxidase, respectively. MMI prevents the IFN-gamma and H(2)O(2)-mediated reversible inactivation of phosphatases. These effects inhibit full activation of the IFN-gamma-induced Janus kinase(JAK)/STAT signaling pathway in FRTL-5 thyroid cells. These results may in part explain the antioxidant and immunomodulatory effects of MMI in thyroid cells of Graves' disease patients.

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.

Immunologic effects of human peripheral and intrathyroidal lymphocytes on xenotransplanted human thyroid tissue in athymic nude mice

T cells are intimately involved in the etiology and pathogenesis of human autoimmune thyroid disease. In order to further elucidate the immunologic mechanisms leading to Graves' disease (GD), we investigated the effects of human lymphocytes derived from patients with autoimmune and nonautoimmune thyroid diseases on human thyroid tissue xenotransplanted into nude mice. Eight weeks after transplantation of thyroid tissue from 26 patients with nonautoimmune thyroid disease (nontoxic nodular goiter [NTG]) into nude mice, peripheral (PBL) and intrathyroidal lymphocytes (ITL) from 14 patients with NTG and 12 patients with GD were engrafted into the animals. ITL and PBL subsets were analyzed by flow cytometer before engraftment. Two days after lymphocyte engraftment, the thyroid transplants were examined histologically (HE) as well as immunohistologically by staining with monoclonal antibodies directed against CD3 (T-cell activation and signal transduction), immunoglobulin G (IgG), HLA class II and CD31 (human endothelium). After injection of GD lymphocytes, thyroid transplants contained significantly more CD3, HLA class II, and CD4 expressing cells. Engrafted PBL and especially ITL from patients with GD specifically migrated into human thyroid transplants but not into the mouse thyroids, induced expression of class II products and led to IgG production by plasma cells. Persistence of human endothelium has been proven by positive CD31 staining. In conclusion, our data demonstrate that an organ-specific immune response is induced only by GD lymphocytes that migrate specifically into the thyroid transplants. Persistence of human endothelial cells in the transplants suggests that homing in this in vivo model reflects the situation in GD patients.

A randomized trial of short-term treatment of Graves' disease with high-dose carbimazole plus thyroxine versus low-dose carbimazole

OBJECTIVE

The optimal treatment regimen with thionamide drugs remains a matter for debate. We have investigated whether high doses of carbimazole, when compared with low doses, reduce relapse rates of Graves' disease.

DESIGN

In an open label, randomized, prospective trial of treatment of Graves' disease we compared high doses of carbimazole (6 months of 100 mg carbimazole per day plus thyroxine) to low-dose carbimazole treatment (starting at 25 mg and titrating the carbimazole dose with the aim to maintain serum thyroid function test results within the normal reference range).

PATIENTS

Thirty-seven patients with a first episode of Graves' disease were enrolled.

MEASUREMENTS

During the 6 months of treatment we evaluated the rate of normalization of serum thyroid function tests, changes in serum thyroid auto-antibody levels and the rate of side-effects during treatment. After completion of the 6-month treatment course patients were observed for 2 years for evidence of relapse of Graves' disease.

RESULTS

There were no differences between the two groups either in the rate of normalization of serum thyroid function tests or in serum thyroid auto-antibody levels during treatment. Of the 17 patients randomized to high-dose treatment seven suffered treatment side-effects, compared to only one of the 20 patients receiving low-dose treatment (P < 0.006). There was no significant difference in 2-year post-treatment remission rates on an intention-to-treat basis between the two treatment groups (18.7% vs. 5.9%, P = NS). However, for those patients who completed 6 months of treatment (high-dose group = 9, low-dose group = 16), multivariate survival analysis demonstrated a significantly longer median relapse-free interval (P < 0.04) in the high-dose group (27 weeks; 25th percentile: 9.6 weeks, 75th percentile: 75 weeks) versus the low-dose group (6 weeks; 25th percentile: 4.8 weeks, 75th percentile: 13.1 weeks).

CONCLUSIONS

High-dose carbimazole treatment delays, but does not prevent, relapse from Graves' disease in those patients able to tolerate the treatment. However, it leads to more frequent side-effects than conventional dose treatment.

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.

Thymic hyperplasia in patients with Graves' disease. Identification of thyrotropin receptors in human thymus

Thymic size and density were studied in 23 untreated patients with Graves' disease and 38 control subjects using computed tomography. Both thymic size and density were higher in untreated patients with Graves' disease than in control subjects in the age-matched group. After treatment with antithyroid drugs, both thymic size and density were significantly reduced, with a concomitant decrease in thyrotropin receptor antibodies. PCR of human thymic cDNA using primers for human thyrotropin receptor amplified a fragment in a size expected for the receptor, and its nucleotide sequence was identical to human thyrotropin receptor cDNA in the thyroid. Northern blot analysis of human thymic poly(A)+ RNA demonstrated the presence of the full length form of thyrotropin receptor mRNA. Western blot analysis of human thymic membrane using anti-thyrotropin receptor peptide antibodies demonstrated a band of 100 kD that was also observed in the thyroid membrane. Immunohistochemistry of thymic tissue using mouse antihuman thyrotropin receptor monoclonal antibodies demonstrated the immunostaining of epithelial cells. These results indicate that thymic hyperplasia is apparently associated with Graves' disease and suggest that thymic thyrotropin receptor may act as an autoantigen that may be involved in the pathophysiology of development of Graves' disease.

Lack of effect of thyroxine in patients with Graves' hyperthyroidism who are treated with an antithyroid drug

BACKGROUND

Antithyroid drugs are effective in patients with hyperthyroidism due to Graves' disease, but the rate of recurrence after treatment is high. In a recent Japanese study, adjunctive treatment with thyroxine (T4) was associated with a recurrence rate 20 times lower than that among patients who received only an antithyroid drug. If these results are confirmed, combined therapy with an antithyroid drug and T4 might become the treatment of choice for all patients with Graves' hyperthyroidism.

METHODS

We treated 111 patients (89 women and 22 men) who had Graves' hyperthyroidism. All patients initially received 40 mg of carbimazole daily for one month. Then one group received carbimazole alone for 17 months (52 patients), and the other group received carbimazole plus T4 for 17 months and T4 alone for 18 months (59 patients). In the carbimazole group, the dose was adjusted after one month to maintain a normal serum thyrotropin concentration. In the carbimazole-T4 group, the dose of carbimazole was not changed, but 100 micrograms of T4 per day was added to the regimen and the dose was adjusted to maintain an undetectable serum thyrotropin concentration (< 0.04 microU per milliliter).

RESULTS

At the time of our analysis, 53 of the 111 patients had completed at least 3 months of follow-up (median, 12 months) after carbimazole was withdrawn. Hyperthyroidism recurred in eight patients in each group after a mean (+/- SD) of 6 +/- 4 months in the carbimazole group and 7 +/- 4 months in the carbimazole-T4 group. There was no difference between the recurrence rates in the two groups, despite the fact that serum thyrotropin concentrations were undetectable in 73 percent of patients in the carbimazole-T4 group on at least 75 percent of their visits.

CONCLUSIONS

The administration of T4 to patients with Graves' disease during carbimazole treatment and after its withdrawal neither delays nor prevents the recurrence of hyperthyroidism.

Response to methimazole in Graves' disease. The European Multicenter Study Group

OBJECTIVE

A variety of regimens continue to be used in the treatment of Graves' disease with antithyroid drugs. We have investigated the factors which determine the initial response to methimazole (time until euthyroidism is achieved) in Graves' disease.

PATIENTS

Five hundred and nine patients with Graves' disease in different European countries with normal and subnormal iodine supply. Patients were randomized to treatment with either 10 or 40 mg of methimazole per day for one year, with levothyroxine supplementation as required to maintain euthyroidism. Investigations were carried out before treatment and at 3 and 6 weeks and 3, 6, 9 and 12 months.

MEASUREMENTS

Response was assessed by serial measurements of serum thyroid hormones. TSH receptor antibodies, thyroid autoantibodies and urinary iodide excretion were measured centrally. Twenty-minute thyroid uptake was measured by standard techniques. Data were collected and analysed centrally. Standard techniques as well as a stepwise logistic regression model were used to examine the relations between methimazole dose, age, goitre size, presence of endocrine eye signs, thyroid hormone levels, urinary iodide excretion, thyroid uptake, index of disease severity (Crooks), presence of TSH receptor antibodies and duration of the hyperthyroid phase.

RESULTS

Within 3 weeks, 40.2% of patients responded to 10 mg of methimazole and 77.5% responded within 6 weeks. The corresponding figures for 40 mg of methimazole were 64.6 and 92.6%. Significant associations were found between duration of hyperthyroidism and the following variables: goitre size, urinary iodide excretion, methimazole dose, presence of TSH receptor antibodies (TBIAb), index of disease severity (Crooks) and pretreatment thyroid hormone levels. Response to methimazole was delayed in patients with large goitres, iodine excretion of > or = 100 micrograms/g creatinine, high pretreatment thyroid hormone levels, elevated levels of TBIAb and treatment with only 10 mg of methimazole. In the 10-mg group, 46% of patients were euthyroid within 3 weeks when urinary iodide was < 50 microgram/g of creatinine, and only 27% when iodide was above 100 micrograms/g. By stepwise logistic regression, the main factors for the response to methimazole were daily dose, pretreatment T3 levels, and goitre size.

CONCLUSION

Methimazole dose, pretreatment serum T3 levels, and goitre size are the main determinants of the therapeutic response to methimazole in Graves' disease, at least in areas comprising low, subnormal and normal iodine supply.

Short-term treatment of Graves' disease with methimazole in high versus low doses

OBJECTIVES

To compare the relapse rates in Graves' disease the first 2 years after methimazole 60 mg day-1 combined with thyroxine versus a titration regimen with methimazole alone, and to look for possible prognostic factors.

DESIGN

A randomized, open, prospective study. Methimazole was given for 6 months in both groups, and thyroid status evaluated every 3rd month during the first year, and every 6th month during the second year.

SETTING

The study was performed at our outpatient clinic with patients referred from primary care.

SUBJECTS

Fifty-six patients were included. One became pregnant and one dropped out during the treatment period. Furthermore, nine patients in the high-dose and four in the low-dose group stopped the treatment because of side-effects. Thus, 19 patients in the high- and 22 in the low-dose group completed 6 months with methimazole.

RESULTS

In those tolerating the treatment, the relapse rates in the high- and low-dose groups were 26.3 vs. 59.1% (P < 0.05), 42.1 vs. 77.3% (P < 0.02); and 57.9 vs. 77.3% (NS) after 3, 12 and 24 months, respectively. The corresponding relapse rates calculated on an 'intention to treat' basis were: 51.7 vs. 66.7%; 62.1 vs. 81.5%: 72.4 vs. 81.5% (NS). The thyroid volume was significantly (P < 0.05) larger in those that relapsed (17.8 +/- 2.9 vs. 11.6 +/- 1.2 mL; mean +/- SEM).

CONCLUSIONS

In those tolerating the treatment, methimazole significantly reduced the relapse rate the 1st year when given in a high dose. However, the relapse rates in both groups, and the number of side-effects in the high-dose group, were unacceptably high.

Simple and reliable method for predicting the remission of Graves' disease: revised triiodothyronine-suppression test, indexed by serum thyroxine

To find a simple and reliable method for predicting the long-term remission of Graves' disease, we studied the outcome of 182 methimazole-treated patients with Graves' disease, whose thyroidal RAIU became < 12% after T3 administration. The patients were treated with methimazole over 2 years. T3 suppression test was done 6 months after the disappearance of TSH-receptor antibody (TRAb); the patients took T3 for 14 days, and on the 14th day, blood was obtained for serum T3, T4, and TSH determination, and RAIU was measured. These 182 patients were followed for 5 years after methimazole withdrawal. We divided the 182 methimazole-treated patients, whose thyroidal RAIU became < 12% after T3 administration, into two groups based on the outcome after the discontinuation of methimazole; 40 patients (22%) had an overt recurrence (group A) and the other 142 (78%) did not (group B). The degree of serum T4 suppressibility by T3 was less in group A than in group B. In group A, the number of the patients with a serum T4 < 60% of the pre-T3 levels is less than that with a serum T4 > or = 60%, but, in group B the former is more than the latter. The serum T4 < 60% of the pre-T3 level was significantly associated with the remission.(ABSTRACT TRUNCATED AT 250 WORDS)

The Pathogenesis of Graves’ Disease

We have hypothesized over many years that Graves' disease (GD) and the other autoimmune thyroid diseases (AITD) are each due to antigen-specific defects in suppressor (regulatory) T lymphocyte function. There have been several reports dealing with the role of regulatory T lymphocyte subsets, ie., that will prevent autoimmune disease in these and other organ-specific autoimmune diseases. In AITD, suppressor T cells have been shown to be less well activated by relevant antigen, but are normally activated by irrelevant antigen; suppressor T cells from normal persons react equally well to both. In GD, these cells have been shown to be inadequately activated by TSH receptor antigen, but are normally activated by irrelevant autoantigen. This reduction is partial only, and insufficient itself to precipitate the autoimmune disease; further insults from the environment are necessary to further reduce generalized regulatory cell activity, adding to the genetically induced specific regulatory cell dysfunction, which appears in turn to be due to a specific defect in the presentation of a specific antigen. This, in turn, may relate to abnormalities of the genes responsible for antigen presentation. The end result is activation of appropriate helper and effector T cells, the stimulation by these of appropriate B lymphocytes, and the concurrent production of cytokines. These events lead to functional changes within the target cell which itself will express Class II antigens, heat shock proteins, and intercellular adhesion molecules, all of which amplify the immune response. Moreover, the activation of helper T lymphocytes by specific antigen depends on the availability of normal amounts of antigen being presented to them by antigen-presenting cells. Thus, there is no need to invoke any primary abnormality or infection of the thyroid cell, or any cross-reacting antigen of microorganismic origin to initiate this process. What is required is an abnormality of antigen-presentation such that regulatory cells are not properly activated, plus some additive environmental disturbance acting on the immune system. GD specifically results from the production by B lymphocytes of an antibody directed against the TSH receptor which stimulates the thyrocyte in a manner similar to TSH, but for a much longer interval. There are also antibodies to the thyrotrophin (TSH) receptor which block the action of TSH. Thyroid stimulating antibody is typical of GD and is detectable in about 95% of cases, but is also seen in destructive thyroiditis transiently. It tends to decline with antithyoid drug therapy, and rises further (for several months) after 131 I treatment. It may slowly decline after subtotal thyroidectomy. It also declines in the third trimester of pregnancy but sometimes is sufficiently high to cause foetal and neonatal passive transfer GD. It tends to rebound in the mother after delivery and may result in postpartum GD. The blocking antibody may cause atrophic thyroiditis and hypothyroidism. Antimicrosomal antibody has now been shown to be antithyroperoxidase. It correlates moderately well with thyroid dysfunction in Hashimoto's thyroiditis (HT) and GD, while antithyroglobulin is of much less value. Graves' ophthalmopathy is still not well understood, and its precise relationship to Graves' hyperthyroidism has yet to be worked out. However the retroorbital fibroblast is now emerging as the most likely target cell, with retroorbital muscle involvement possibly secondary. A recent observation of a genomic point mutation on the TSH receptor on fibroblasts from patients with Graves' ophthalmopathy but not normal persons raises interesting possibilities.

Anti-thyroid peroxidase (anti-TPO) antibodies in thyroid diseases, non-thyroidal illness and controls. Clinical validity of a new commercial method for detection of anti-TPO (thyroid microsomal) autoantibodies

The identification of the thyroid peroxidase (TPO) as the main antigen of the thyroid microsomal fraction has enabled the development of a sensitive and specific assay for detection of the corresponding autoantibodies. We evaluated the diagnostic validity of the anti-TPO assay in 303 patients with different types of thyroid disease and in controls. Clearly elevated anti-TPO values (anti-TPO > 500 units/ml) were found in 59% of patients with thyroiditis but in none of the controls or the patients with non-thyroidal illness. The mean anti-TPO levels in these two control groups were 26 +/- 31 units/ml (mean +/- S.D.) and 39 +/- 34 units/ml, respectively. The highest frequency of positive results (88%) was obtained in patients with auto-immune hypothyroidism (clinical diagnosis: Hashimoto's thyroiditis) followed by patients with Graves' disease (53%). With a cut-off point of 200 units/ml, a sensitivity of 96% was obtained for Hashimoto's thyroiditis and of 59% for Graves' disease with a specificity of 100% (50 cases). The new method (anti-TPO, Dynotest) was compared with three conventional methods (35 samples). The results for all measurements were in general agreement. In two cases the results were clearly discordant: one sample contained high anti-thyroglobulin antibody concentrations, the other was obtained from a patient with non-thyroidal illness. In both instances the 'classical' assays yielded false-positive results. Treatment of autoimmune hyperthyroidism resulted in a median decrease in anti-TPO levels of over 50% after reaching the euthyroid state (P < 0.05), whereas in persistent hyperthyroidism no consistent changes were observed. In autoimmune hypothyroidism a marked variability in anti-TPO levels was noted. Some patients showed a clear decrease in anti-TPO levels during T4 substitution whereas in others no consistent changes were observed.