Treatment of amiodarone induced hyperthyroidism with potassium perchlorate and methimazole during amiodarone treatment.

To exploit the antiarrhythmic effect of amiodarone when patients develop the side effect of thyrotoxicosis three patients with hyperthyroidism induced by amiodarone were given simultaneously 1 g potassium perchlorate a day for 40 days and a starting dose of 40 mg methimazole a day while they continued to take amiodarone. As hyperthyroidism might have recurred after potassium perchlorate treatment was stopped the dose of methimazole was not reduced until biochemical hypothyroidism (raised thyroid stimulating hormone concentrations) was achieved. The patients became euthyroid (free triiodothyronine concentration returned to normal values) in two to five weeks and hypothyroid in 10 to 14 weeks. One patient became euthyroid while taking 5 mg methimazole a day and 600 mg amiodarone weekly; the two others required substitution treatment with thyroxine sodium while taking 5 mg methimazole or 50 mg propylthiouracil (because of an allergic reaction to methimazole) and 2100 or 1400 mg amiodarone weekly. Hyperthyroidism induced by amiodarone may be treated with potassium perchlorate and methimazole given simultaneously while treatment with amiodarone is continued.     

健脾消瘿汤联合优甲乐对脾气亏虚型桥本甲状腺炎患者甲状腺激素、甲状腺自身抗体和CD4+CD45RO+记忆性T细胞的影响

摘要 目的：探讨健脾消瘿汤联合优甲乐对脾气亏虚型桥本甲状腺炎（HT）患者甲状腺激素、甲状腺自身抗体和CD4+CD45RO+记忆性T细胞的影响。方法：选择2020年5月~2021年11月期间我院收治的HT患者60例，采用随机数字表法分为对照组（优甲乐治疗，30例）和研究组（健脾消瘿汤联合优甲乐治疗，30例），两组均治疗12周后观察临床疗效，并对比两组治疗前后中医证候积分、甲状腺激素、甲状腺自身抗体和CD4+CD45RO+记忆性T细胞的变化。结果：研究组临床总有效率较对照组高（P<0.05）。研究组治疗后促甲状腺激素（TSH）水平、中医证候总积分、CD4+CD45RO+记忆性T细胞在外周血单个核细胞（PBMC）中的百分比、甲状腺球蛋白抗体（TGAb）、甲状腺过氧化物酶抗体（TPOAb）均低于对照组（P<0.05），游离三碘甲状腺原氨酸（FT3）、游离甲状腺素（FT4）水平高于对照组（P<0.05）。结论：脾气亏虚型HT患者采用健脾消瘿汤联合优甲乐治疗，可改善其甲状腺激素水平，调节甲状腺自身抗体水平和CD4+CD45RO+记忆性T细胞在PBMC中的百分比，进一步提高临床疗效。     

甲状腺乳头状癌合并桥本氏甲状腺炎的BRAF基因表达及侵袭性

目的:比较甲状腺乳头状癌合并桥本氏甲状腺炎与不合并桥本氏甲状腺炎的BRAFV600E基因表达以及侵袭性的区别。方法:2011年9月到2013年9月四川大学华西医院手术治疗并有BRAFV600E基因测定的甲状腺乳头状癌患者226名,均有病理证实。其中合并桥本氏甲状腺炎者50例为研究组,同期随机抽取50例不合并桥本氏甲状腺炎者作为对照组。比较两组性别、年龄、肿瘤大小、数量、BRAFV600E基因表达以及甲状腺外侵犯和淋巴结转移与侵袭性相关的因素的区别。结果:甲状腺乳头状癌合并桥本氏甲状腺炎在男女性别,发病年龄、肿瘤大小上和对照组相比无差异(P0.05);BRAFV600E突变率、甲状腺外侵犯和淋巴结转移都较对照组更低(P0.05)。BRAF基因突变阳性组甲状腺外侵犯和淋巴结转移率较BRAFV600E基因突变阴性组更高(P0.05)。结论:BRAFV600E基因突变的甲状腺乳头状癌患者有更高的甲状腺腺外侵犯和淋巴结转移。甲状腺乳头状癌合并桥本氏甲状腺炎较不合并桥本氏甲状腺炎有着更低的BRAFV600E突变率,更低的甲状腺外侵犯和淋巴结转移。     

Genetic Factors in Hashimoto's Struma

It has previously been established that there is a significant history of thyroid disorders in families of patients with Hashimoto''s struma or chronic thyroiditis. In the present study, 99 relatives of 20 patients with Hashimoto''s struma or chronic thyroiditis were studied with regard to the incidence of circulating thyroid autoantibodies; 42 of these 99 relatives were found to have such antibodies. Twenty of the 99 relatives were shown to have thyroid abnormalities (chiefly goitre); of this group of 20, antibodies were found in 12. In the remaining 79 persons (who had no clinical evidence of thyroid disease), 30 were found to have circulating antithyroid antibodies. The incidence of such antibodies among these relatives is very significantly greater than in the general population.From these and other similar studies, there is strong evidence favouring a genetic predisposition for Hashimoto''s struma and chronic thyroiditis. The mode of inheritance is not yet established, and the pathogenesis of the disease has not yet been elucidated.     

Acute thyroid dysfunction (thyroiditis) after therapy with interleukin-2.

Interleukin-2 (IL-2) is frequently incorporated in antineoplastic therapy: While the effect of interferon on the thyroid has been extensively studied the impact of other cytokines on thyroid function is less well understood. We monitored the thyroid function in six patients who received IL-2 in combination with tumor necrosis factor-alpha (TNF) or alpha-Interferon (alpha IFN). Hyperthyroxinemia with suppressed TSH developed within the first four weeks of IL-2 administration; during this phase, there was no technetium or iodine uptake by the thyroid gland. During the following few weeks, serum thyroxine decreased and serum TSH rose, consistent with the development of primary hypothyroidism; during this phase, thyroidal isotope incorporation was normal. All hypothyroid patients received thyroxine replacement therapy upon documentation of hypothyroidism; in several cases thyroxine was successfully discontinued after 2-3 months. None of the patients had detectable antithyroidal antibodies and none experienced thyroid-related pain, although two patients developed thyroid enlargement. We conclude that IL-2 administration is associated with the development of transient, subacute, painless thyroiditis. The frequency and severity of this complication requires further elucidation through systematic, prospective study.     

Obituaries

The outcome in 110 patients first treated with radioiodine (mean dose 6.56 mCi) for hyperthyroid Graves'' disease in 1980 was reviewed. In 23% of the patients the disease had not been controlled by the initial dose after 3 months, and 17% were given one or two more doses. Within 2 years 65% of the patients required replacement thyroxine therapy. Although about half of the patients were biochemically hypothyroid 3 months after the last dose of iodine 131, this condition was transient in a third of them; five of these patients even became hyperthyroid again. Patients with transient, as opposed to permanent, hypothyroidism at 3 months tended to be clinically euthyroid but to have residual palpable thyroid tissue and only a modest reduction in the serum thyroxine level. It is therefore recommended that patients not overtly hypothyroid 3 months after treatment with 131I be observed still longer before thyroxine replacement therapy is instituted.     

Urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in patients with Graves' disease, subacute thyroiditis, and silent thyroiditis: a longitudinal study.

Urinary N-acetyl-beta-D-glucosaminidase (NAG) activity was measured longitudinally in 12 patients with Graves' disease, 5 patients with subacute thyroiditis, and 1 patient with silent thyroiditis, and compared with that of 36 normal controls. The patients with Graves' disease and subacute thyroiditis were treated with anti-thyroid drug (methimazole or propylthiouracil) and prednisolone, respectively. On the other hand, no treatment was given to the patient with silent thyroiditis. Since two patients with Graves' disease clearly showed transient deterioration of the thyroid function during the treatment period, data from these two patients were separately investigated. Urinary levels of NAG in the remaining ten patients with Graves' disease before, 1, 3, 6 and 12 months after the treatment were 15.59 +/- 7.93 (SD), 8.96 +/- 6.82, 4.39 +/- 2.33, 3.46 +/- 2.24, and 3.63 +/- 2.38 U/g.creatinine (g.Cr.), respectively. Those obtained before, 1 and 3 months after the treatment were significantly higher than those of the controls (2.85 +/- 1.12 U/g.Cr.). Free thyroid hormone levels became normal or low 3 months after the treatment. The two Graves' patients mentioned above showed a transient increase in urinary NAG with concomitant changes in free thyroid hormone levels. Urinary NAG levels in the patients with subacute thyroiditis before, 2, 4, and 6 weeks after the treatment were 16.56 +/- 10.97, 6.76 +/- 2.79, 3.14 +/- 0.48 and 3.70 +/- 1.44 U/g.Cr., respectively. Those obtained before and 2 weeks after the treatment were significantly higher than those of the controls. Free thyroid hormones were normal 2 weeks after therapy. Urinary NAG in the patient with silent thyroiditis was 9.60 U/g.Cr. on the first visit and gradually decreased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prognostic Value of High 10-Minute I131 Uptake in Non-Toxic Goitres

Forty-two patients with non-toxic goitre and with a high 10-minute uptake of I¹³¹ were treated with 100 μg. of l-triiodothyronine per day for periods up to 36 months. All of the goitres were reduced in size and 10 showed marked regression within one week. Hashimoto''s disease was considered an unlikely cause of these goitres because only four of 20 tested had positive antithyroglobulin tests, and these were of low titre (up to 1:81). Chromatographic studies suggested a defect in thyroxine metabolism in many of these patients. It is concluded that a high 10-minute uptake test is useful in predicting a response to therapy and in selecting patients likely to have a detectable defect in thyroxine metabolism.     

Hashimoto's thyroiditis with immunoblastic lymphadenopathy and unusual "macaroni cells".

Light and electron microscopic study of the thyroid gland and an enlarged cervical lymph node in a 75-year-old woman with Hashimoto''s thyroiditis disclosed immunoblastic proliferation in the lymph node, marked by collections of striking round cells positive to periodic acid-Schiff (PAS) staining, immunoblasts and plasmacytoid elements in a vascular, fibrous framework. The PAS-positive cells ("macaroni cells") were distended with whorls of angulated tubular material resembling endoplasmic reticulum. Parafollicular-cell hyperplasia and an atypical plasmacytoid focus were noted in the thyroid. Hashimoto''s disease is known to be associated with malignant lymphoma, as are autoimmune and malignant diseases with immunoblastic lymphadenopathy. This is the first report of the association of Hashimoto''s disease and immunoblastic lymphadenopathy. The atypical plasma cells have not previously been described.     

The effect of thyroid hormones on the aerobic development of locomotor and cardiac muscles in the barnacle goose

The role of thyroid hormones in the development of the locomotor and cardiac muscles of the barnacle goose (Branta leucopsis) was investigated. From 2 weeks of age, goslings were treated with thyroxine, triiodothyronine, or methimazole (a thyroid inhibitor). Birds were killed at 6 weeks (n = 5) or 9 weeks (n = 4) and various locomotor and cardiac muscle masses recorded and tissue samples taken for analysis of citrate synthase activity. The effects of thyroxine and triiodothyronine were not significantly different from each other, except in the case of the iliofibularis at 9 weeks. The mass-specific citrate synthase activity of the iliofibularis, semimembranosus muscles and liver were significantly increased by thyroid hormone treatment. Cardiac muscle showed a significant hypertrophy at 9 weeks of age following treatment with thyroxine. Hypothyroidism induced by treatment with methimazole exhibited the greatest effect on the pectoralis muscle, reducing citrate synthase activity by 33%. Mass-specific citrate synthase activity of the pectoralis and pectoralis mass (% body wt.) were found to be highly correlated (r ² = 0.74) at 6 weeks of age. It is suggested that thyroid hormones may be involved in controlling the tissue-specific timing of the maturation of locomotor and cardiac muscles. Accepted: 16 September 1996     

Effect of acute and chronic administration of L- thyroxine and methimazole on blood levels of tryptophane, serotonin and 5-hydroxyindoleacetic acid in plasma of rats]

The effects of hyperthyreosis induced by the administration of thyroxine and hypothyreosis induced by the administration of methimazole on the levels of tryptophane, serotonin and 5-hydroxyindoleacetic acid in low-platelet blood plasma have been studied in Wistar rats. Thyroxine administration (120 micrograms/kg/24 h, intraperitoneally) lasting 7 days caused a decrease in serotonin concentration by 38 per cent. The level of this amine in rats receiving thyroxine during three months was elevated by almost three times. Tryptophane concentration did not change following thyroxine administration. Methimazole administration lasting 14 days (oral dose 15 mg/kg/24 h) caused an increase in tryptophane concentration by 34 per cent and in serotonin concentration by 24 per cent. Long-term hypothyreosis induced by methimazole administration lasting three months caused an 39 per cent increase in tryptophane and 38 per cent increase in serotonin concentration. Neither hyperthyreosis induced by thyroxine administration nor hypothyreosis induced by methimazole++ caused any changes in the concentration of 5-hydroxyindoleacetic acid. The importance of serotonin in pathogenesis of clinical symptoms accompanying the states of deficit or excess of thyroid hormones needs further elucidation.     

Influence of chronically altered thyroid status on the activity of liver mitochondrial glycerol-3-phosphate dehydrogenase in female inbred lewis rats.

The activity of liver mitochondrial flavoprotein-dependent glycerol-3-phosphate dehydrogenase (GPDH) is considered a reliable marker of thyroid status in acute and short-lasting experiments. The aim of this study was to ascertain whether GPDH activity could also be used as an index of thyroid status during chronic experiments over several months. We therefore analyzed GPDH activity in liver mitochondria of female inbred Lewis rats with thyroid status altered for 2 to 12 months. Hyperthyroid state was maintained by triiodothyronine (T (3)) or thyroxine (T (4)) administration, while methimazole was employed for inducing hypothyroidism. We found a seven- and three-fold increase of GPDH activity in female rats after T (3) or T (4) administration, respectively, compared to euthyroid females (8.9 +/- 2.3 nmol/min/mg protein), whereas administration of methimazole reduced the enzyme activity almost to one-third of the euthyroid values. These changes were not significantly influenced by the duration of hyperthyroid or hypothyroid treatment. We conclude that the level of the rat liver GPDH activity could serve as a useful marker for evaluation of hyperthyroid and hypothyroid status in chronic long-lasting experiments on female inbred Lewis rats.     

Effect of thyroid hormone on epidermal growth factor-like immunoreactivity and growth velocity in cynomolgus monkeys

To examine the potential role of epidermal growth factor (EGF) in mediating the effects of thyroid hormone on linear growth, we measured serum EGF levels by RIA in cynomolgus monkeys before and during methimazole-induced hypothyroidism, and after 9 weeks of T4 replacement at different doses. Ten castrated prepubertal monkeys were rendered hypothyroid by methimazole (0.0125% in drinking water for 12 weeks). Methimazole was continued, and T4 was then administered for 9-week intervals. Six weeks elapsed between successive T4 doses. The sequence of different T4 doses for each animal was random. Serum EGF level was measured at baseline and at the end of each treatment period with a newly developed RIA using a polyclonal antiserum against human recombinant EGF. Serum EGF level correlated significantly with the level of serum thyroxine but not with serum triiodothyronine, over the thyroxine dosage range of 1-4 micrograms/kg/day (r = 0.41, p less than 0.005). Lower-leg growth rate correlated significantly with serum EGF level over this same thyroxine dosage range (r = 0.41, p less than 0.005). These data are consistent with the hypothesis that EGF may mediate some of the effects of thyroid hormone on skeletal growth.     

Maximum acute exercise tolerance in hyperthyroid and hypothyroid rats subjected to forced swimming

Thyroid dysfunction can compromise physical capacity. Here, we analyze the effects of hyperthyroidism and hypothyroidism on maximum swim time in rats subjected to acute forced swimming, as an indicator of anaerobic capacity. Animals were forced to swim against a load (5% of body weight) attached to the tail and were killed 48 hours after the last test. Hyperthyroid rats were treated with thyroxine (50 mug/100 g body weight, i. p. for 7 days). The hypothyroid group received 0.03% methimazole in the drinking water for 4 weeks. Thyroid state was confirmed by alterations in serum thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and liver mitochondrial glycerol phosphate dehydrogenase (mGPD) activity. Hyperthyroid rats presented significantly lower visceral fat mass (VFM) and higher food intake (p<0.05) with unchanged body weight. Maximum swim time (MST), glycogen content (skeletal muscle and liver), and leptin levels were lower while corticosterone was higher (p<0.05). In hypothyroid rats body weight was lower (p<0.05), without changes in VFM. Tested at 7-day intervals, MST was lower for tests 2, 3, and 4 (p<0.05). Muscle glycogen was higher in extensor digitorum longus (EDL) and soleus (p<0.05), without changes in liver. Serum corticosterone was lower, while leptin was higher (p<0.05). These results suggest that in hyperthyroid and hypothyroid rats, thyroid hormones together with corticosterone and/or leptin may impair exercise capacity differently through its known effects on glycogen metabolism.     

Hypothyroidism after Thyroidectomy for Graves's Disease: A Search for an Explanation

Out of 38 patients who had undergone subtotal thyroidectomy for Graves''s disease seven to 20 years previously 15 developed hypothyroidism. In these 15 patients autoantibodies against thyroid cytoplasm were significantly more frequent than in the 23 euthyroid patients, though there was no difference in the prevalence of autoantibodies against thyroglobulin. Histological examination of the thyroid tissue removed at operation showed that significantly more plasma cells and lymphoid follicles with germinal centres were present in patients who subsequently developed hypothyroidism than in those who remained euthyroid. No differences in the amount of lymphocytic infiltration were seen in hypothyroid and euthyroid patients.The results suggest that B lymphocytes play a part in the development of postoperative hypothyroidism in Graves''s disease. It is proposed that Graves''s disease and Hashimoto''s disease are different aspects of the same basic autoimmune process.     

Dynamics of thyroid diseases and thyroid‐axis gland masses

Thyroid disorders are common and often require lifelong hormone replacement. Treating thyroid disorders involves a fascinating and troublesome delay, in which it takes many weeks for serum thyroid‐stimulating hormone (TSH) concentration to normalize after thyroid hormones return to normal. This delay challenges attempts to stabilize thyroid hormones in millions of patients. Despite its importance, the physiological mechanism for the delay is unclear. Here, we present data on hormone delays from Israeli medical records spanning 46 million life‐years and develop a mathematical model for dynamic compensation in the thyroid axis, which explains the delays. The delays are due to a feedback mechanism in which peripheral thyroid hormones and TSH control the growth of the thyroid and pituitary glands; enlarged or atrophied glands take many weeks to recover upon treatment due to the slow turnover of the tissues. The model explains why thyroid disorders such as Hashimoto''s thyroiditis and Graves'' disease have both subclinical and clinical states and explains the complex inverse relation between TSH and thyroid hormones. The present model may guide approaches to dynamically adjust the treatment of thyroid disorders.     

RET/PTC Rearrangements Are Associated with Elevated Postoperative TSH Levels and Multifocal Lesions in Papillary Thyroid Cancer without Concomitant Thyroid Benign Disease

RET/PTC rearrangements, resulting in aberrant activity of the RET protein tyrosine kinase receptor, occur exclusively in papillary thyroid cancer (PTC). In this study, we examined the association between RET/PTC rearrangements and thyroid hormone homeostasis, and explored whether concomitant diseases such as nodular goiter and Hashimoto''s thyroiditis influenced this association. A total of 114 patients diagnosed with PTC were enrolled in this study. Thyroid hormone levels, clinicopathological parameters and lifestyle were obtained through medical records and surgical pathology reports. RET/PTC rearrangements were detected using TaqMan RT-PCR and validated by direct sequencing. No RET/PTC rearrangements were detected in benign thyroid tissues. RET/PTC rearrangements were detected in 23.68% (27/114) of PTC tissues. No association between thyroid function, clinicopathological parameters and lifestyle was observed either in total thyroid cancer patients or the subgroup of patients with concomitant disease. In the subgroup of PTC patients without concomitant disease, RET/PTC rearrangement was associated with multifocal cancer (P = 0.018). RET/PTC rearrangement was also correlated with higher TSH levels at one month post-surgery (P = 0.037). Based on likelihood-ratio regression analysis, the RET/PTC-positive PTC cases showed an increased risk of multifocal cancers in the thyroid gland (OR = 5.57, 95% CI, 1.39–22.33). Our findings suggest that concomitant diseases such as nodular goiter and Hashimoto''s thyroiditis in PTC may be a confounding factor when examining the effects of RET/PTC rearrangements. Excluding the potential effect of this confounding factor showed that RET/PTC may confer an increased risk for the development of multifocal cancers in the thyroid gland. Aberrantly increased post-operative levels of TSH were also associated with RET/PTC rearrangement. Together, our data provides useful information for the treatment of papillary thyroid cancer.     

血清甲状腺过氧化物酶抗体对合并桥本甲状腺炎甲状腺微小癌淋巴结转移影响

目的:探讨合并桥本甲状腺炎的甲状腺微小乳头状癌淋巴结转移的特点,分析血清甲状腺过氧化物酶抗体(Thyroid peroxidase-antibody,TPO-Ab)滴度对该组病例淋巴结转移的影响。方法:回顾性分析武汉同济医院甲状腺乳腺外科2012年1月至2014年5月收治的甲状腺微小癌伴桥本甲状腺炎的病例,运用卡方检验、阈值效应分析、多因素logistic回归方法分析该组病例血清TPO-Ab滴度对淋巴结转移的影响。结果:共收集75例合并桥本甲状腺炎的微小乳头状癌病例,血清TPO-Ab滴度与淋巴结转移相关:抗体滴度对淋巴结转移的影响存在分段特征,有阈值效应,该组病例以212 IU/m L为阈值;多因素logistic回归显示,随着血清TPO-Ab水平升高,淋巴结转移率下降(OR=0.993,95%CL=0.987,0.999,P=0.018)。结论:合并桥本甲状腺炎的甲状腺微小乳头状癌病例,血清TPO-Ab滴度对淋巴结转移的影响可能存在阈值效应,值得深入分析;且高血清TPO-Ab滴度可能是淋巴结转移的保护因素,但两者的相互关系尚需进一步探讨。     

Changes in serum thyroid hormone autoantibody concentrations during pregnancy: a case report.

A 29-year-old female patient with Graves' disease who developed thyroid hormone autoantibodies (THAA) under treatment with methimazole is presented. THAA were identified as IgG-kappa. During a first pregnancy that ended by miscarriage in the 3rd month, the titer of anti-thyroxine autoantibodies decreased by about 30%. Relapse of Graves' disease occurred 2 months later and an increase in serum THAA concentration to the initial titer was observed. THAA titer remained unchanged during treatment with methimazole and afterwards during thyroxine supplementation for radioiodine-induced hypothyroidism. During a second pregnancy, a decrease in anti-thyroxine autoantibody titer reached 45% at the time of delivery and an increase by 20% was noted 5 months later. A similar decline in THAA concentration was shown during a third pregnancy. The changes in THAA concentrations observed during pregnancy suggest an immunological influence of pregnancy on the THAA production, as previously demonstrated in other autoimmune diseases, like Hashimoto's thyroiditis.     

Amiodarone: a common source of iodine-induced thyrotoxicosis

Amiodarone, a iodine-rich drug widely used in the treatment of tachyarrhythmias, represents one of the most common sources of iodine-induced thyrotoxicosis. The data concerning 58 patients with amiodarone-iodine-induced thyrotoxicosis (AIIT) were analyzed in the present study. Prevalence of AIIT was higher in males than in females (M/F = 1.23/l). Thyrotoxicosis occurred either during treatment with or at various intervals after withdrawal of amiodarone. AIIT developed not only in patients with underlying thyroid disorders, but also in subjects with apparently normal thyroid gland. Classical symptoms of thyrotoxicosis were often lacking, the main clinical feature being a worsening of cardiac disorders. Biochemical diagnosis of AIIT was established by the finding of elevated serum total and free triiodothyronine levels, since elevated serum total and free thyroxine could be found also in euthyroid amiodarone-treated subjects. Twenty-four-hour thyroid radioiodine uptake was very low or undetectable in AIIT patients with apparently normal thyroid glands, while it was inappropriately elevated in patients with underlying thyroid disorders, despite iodine contamination. The role of autoimmune phenomena in the pathogenesis of AIIT appeared to be limited, because circulating thyroid autoantibodies were undetectable in AIIT patients without underlying thyroid disorders or with nodular goiter. Conversely, humoral features of thyroid autoimmunity were mostly found in AIIT patients with diffuse goiter. Treatment of AIIT appeared to be a difficult challenge. Among the 11 patients given no treatment, thyrotoxicosis spontaneously subsided in the 5 patients with apparently normal thyroid gland, whereas the 6 patients with nodular or diffuse goiter were still hyperthyroid 6-9 months after discontinuation of the drug. The administration of high doses (40 mg/day) of methimazole alone proved to be ineffective in most (14/16) patients given this treatment. Twenty-seven patients were treated by methimazole combined with potassium perchlorate (1 g/day). With one exception, euthyroidism was restored within 15-90 days in all cases with underlying thyroid abnormalities, and within 6-55 days in subjects with apparently normal thyroid gland. Thus, the combined treatment appears to be the most effective one, but, due to the potential toxicity of potassium perchlorate, it should be reserved to patients with severe thyrotoxicosis and should be carefully monitored.