thyrotoxicosis , which is defined as all clinical statuses resulting from thyroid hormone excess in peripheral blood and tissues , is divided into two major categories by etiology : the presence or absence of accompanying hyperthyroidism . the most common cause of thyrotoxicosis in korea is graves disease ( 82.7% ) , followed by subacute thyroiditis ( 13.3% ) , painless thyroiditis ( 3.5% ) , and toxic adenoma ( 0.5% ) . familial or sporadic nonautoimmune hyperthyroidism due to the germline mutation in the thyroid stimulating hormone ( tsh ) receptor is a rare cause of thyrotoxicosis and should be differentiated from graves disease . graves disease is an autoimmune disorder in which tsh receptor antibodies stimulate the thyroid gland and result in hyperthyroidism , diffuse goiter , ophthalmopathy , and dermopathy . numerous medical and nonmedical factors , including patient compliance , age , size of goiter , symptom severity , patient socioeconomic status , experience and preference of physicians and surgeons , and availability of medical facilities for i therapy , affect the choice of treatment modality . in addition , the most preferred treatment differs from country to country according to the medical insurance system , medical expenses , and patients reluctance to be exposed to radioactive material or surgery . recently , the american thyroid association ( ata ) and the american association of clinical endocrinologists ( aace ) published new management guidelines for hyperthyroidism . however , these guidelines are quite different from clinical practice in korea and are difficult to apply . therefore , the korean thyroid association ( kta ) conducted a survey of kta members regarding the diagnosis and treatment of hyperthyroidism , and subsequently reported the consensus on the management of hyperthyroidism . in this review , we summarized the kta consensus report on the management of hyperthyroidism and compared it with guidelines from other countries . when hyperthyroidism is strongly suspected , the kta guidelines suggest measurement of both serum tsh and free thyroxine ( t4 ) levels at the time of the initial evaluation . the total triiodothyronine ( t3 ) measurement is helpful for the diagnosis of t3-toxicosis . if serum tsh is normal and free t4 is elevated , tsh - producing pituitary adenoma and thyroid hormone resistance should be considered . euthyroid hyperthyroxinemia is mostly due to thyroid hormone - binding protein disorders that cause elevated total t4 and normal tsh concentrations in the absence of hyperthyroidism . a pituitary lesion on magnetic resonance imaging and a high serum level of tsh -subunit support the diagnosis of a tsh - producing pituitary adenoma . a family history and positive result of genetic testing for mutations in the t3-receptor gene support a diagnosis of thyroid hormone resistance . the severity of thyrotoxic symptoms is inversely correlated with age ; therefore , cardiac evaluation , including electrocardiogram , echocardiogram , holter monitor , or the myocardiac perfusion test , may be required for the diagnosis and treatment of ischemic heart disease , congestive heart failure , or atrial arrhythmias in older patients . for the determination of etiology , the kta report remarked on the usefulness of an anti - tsh receptor antibody ( trab ) assay for the diagnosis of graves disease . a second - generation thyrotropin - binding inhibitor immunoglobulin assay , which utilizes human recombinant tsh receptors , showed a specificity of 99% and a sensitivity of 95% for the diagnosis of graves disease . the ata / aace guidelines strongly recommend radioactive iodine uptake test when the clinical presentation of thyrotoxicosis is not diagnostic of graves disease , and also suggest adding a thyroid scan in the presence of thyroid nodularity . in contrast , only 37% ( 50/137 ) of kta members responded that they perform a thyroid uptake test and 61% ( 83/137 ) use a thyroid scan for the diagnosis of hyperthyroidism . furthermore , most of kta members ( 92% , 70/76 ) use tco4 rather than i or i for a thyroid uptake test or thyroid scan . a trab assay is used by 94.5% ( 129/137 ) of kta members for the diagnosis of graves disease . these results show that a trab assay is mainly used for the determination of etiology in thyrotoxicosis , and this trend is also shown in europe and japan . on the other hand , the ata / aace guidelines suggest a trab assay and the ratio of total t3 to total t4 as an alternative method of diagnosing graves disease when a thyroid scan and uptake are unavailable or contraindicated . color doppler ultrasonography is used by only 16.8% ( 23/137 ) of kta members to diagnose hyperthyroidism , whereas doppler flow is generally used in europe and japan . for the symptomatic management of thyrotoxicosis , the kta report recommends -adrenergic blockade . once it has been established that a patient has hyperthyroidism caused by graves disease , the initial treatment options are an antithyroid drug ( atd ) , i therapy ( radioactive iodine ) , and thyroidectomy . in the united states , radioactive iodine has been the most preferred therapy , whereas there has been a greater physician preference for atds in europe and japan . in the kta survey , 97.1% ( 133/137 ) of kta members reported choosing atds and remaining 2.9% ( 4/137 ) chose radioactive iodine for the initial treatment . the ata / aace guidelines recommend that the treating physician and patient should discuss each of the treatment options , including the logistics , benefits , expected speed of recovery , drawbacks , potential side effects , and cost . the long - term quality of life after initial treatment for graves disease was not different among the three treatment options . although atds have been employed for six decades   and are very effective in controlling hyperthyroidism , these medications do not cure graves disease . their major effect is to reduce thyroid hormone synthesis and maintain a euthyroid state while awaiting spontaneous remission . the kta report recommends methimazole or carbimazole for patients who choose atd therapy for graves disease , except during the first trimester of pregnancy , in the treatment of thyroid storm , and in patients with minor reactions to methimazole or carbimazole who refuse radioactive iodine therapy or surgery . in practice , methimazole was chosen as an initial atd by 85.5% ( 112/131 ) of kta members . prophylthiouracil ( ptu ) and carbimazole were chosen by 9.9% ( 13/131 ) and 4.3% ( 6/131 ) of kta members , respectively . the kta report advises higher doses of atds at the start of medication ( methimazole , 10 to 20 mg daily ; ptu , 50 to 150 mg three times daily ) to restore euthyroidism , and the titration to a maintenance level ( methimazole , 5 to 10 mg daily ; ptu , 50 mg two or three times daily ) . the kta report strongly emphasizes notifying all patients of the side effects of atds and proper management for the side effects , including agranulocytosis and hepatotoxicity . if serum tsh , free t4 , and t3 levels have been maintained within normal ranges for 1 year after discontinuation of atd therapy , remission can be considered . the remission rate is approximately 20% to 30% after 12 to 18 months of medication , whereas a long - term european study showed a 50% to 60% remission rate after 5 to 6 years of atd treatment . in japan , maintenance of a minimal dose of atds ( methimazole , 2.5 mg daily ) longer than 6 months after the normalization of tsh is recommended for a higher remission rate . however , a meta - analysis showed that the maintenance of atds longer than 18 months did not improve the remission rate in adults . atds are discontinued after the normalization of both serum tsh and trab by 60% to 70% of kta members . about 30% of respondents answered that they use atds for a fixed duration , most frequently for 12 to 24 months . in case of the recurrence after atd treatment , 46.9% ( 60/128 ) of kta members chose atds again for the treatment of graves disease ; while radioactive iodine and thyroidectomy were chosen by 48.4% ( 62/128 ) and 4.7% ( 6/128 ) of kta members , respectively . in korea , atds are the most preferred modality for retreatment as well as initial treatment , and the treatment duration of atds is longer compared with other countries . this therapy is well tolerated with rare complications , except for those related to ophthalmopathy . the kta report recommends that the use of methimazole or  blockades before and after i treatment may be considered in patients with severe thyrotoxicosis . the ata / aace guidelines remark that if given as pretreatment , methimazole should be discontinued 3 to 5 days before the administration of radioactive iodine , restarted 3 to 7 days later , and generally tapered over 4 to 6 weeks as thyroid function normalizes . in the kta survey , atds were used before and after i treatment by 56% and 43% of kta members , respectively . although the ata / aace guidelines do not recommend a special diet before i therapy , excessive iodine intake should be avoided for at least 7 days before treatment . because daily intake of iodine is more than 500 g in korea , the need for a special diet before i treatment should be validated in future studies . administering a fixed i activity or calculating the activity based on the size of the thyroid and its ability to trap iodine showed no difference in controlling hyperthyroidism by rendering the patient hypothyroid . the kta report recommends sufficient radiation ( 10 to 15 mci ) in a single dose . a pregnancy test should be obtained within 48 hours prior to treatment in any female with childbearing potential . after radioactive iodine therapy for graves disease , a follow - up thyroid function test should be performed within the first 1 to 2 months . if the patient remains thyrotoxic , biochemical monitoring should be continued at 4 to 6 week intervals . the kta report recommends retreatment with i when hyperthyroidism persists after 6 months following i therapy , or if there is minimal response 3 months after therapy . the kta report recommends near - total or total thyroidectomy as the procedure of choice . the optimal preparation for thyroidectomy , the monitoring and treatment strategy for the possible complications , and postoperative management , including t4 replacement , although atds have been employed for six decades   and are very effective in controlling hyperthyroidism , these medications do not cure graves disease . their major effect is to reduce thyroid hormone synthesis and maintain a euthyroid state while awaiting spontaneous remission . the kta report recommends methimazole or carbimazole for patients who choose atd therapy for graves disease , except during the first trimester of pregnancy , in the treatment of thyroid storm , and in patients with minor reactions to methimazole or carbimazole who refuse radioactive iodine therapy or surgery . in practice , methimazole was chosen as an initial atd by 85.5% ( 112/131 ) of kta members . prophylthiouracil ( ptu ) and carbimazole were chosen by 9.9% ( 13/131 ) and 4.3% ( 6/131 ) of kta members , respectively . the kta report advises higher doses of atds at the start of medication ( methimazole , 10 to 20 mg daily ; ptu , 50 to 150 mg three times daily ) to restore euthyroidism , and the titration to a maintenance level ( methimazole , 5 to 10 mg daily ; ptu , 50 mg two or three times daily ) . the kta report strongly emphasizes notifying all patients of the side effects of atds and proper management for the side effects , including agranulocytosis and hepatotoxicity . if serum tsh , free t4 , and t3 levels have been maintained within normal ranges for 1 year after discontinuation of atd therapy , remission can be considered . the remission rate is approximately 20% to 30% after 12 to 18 months of medication , whereas a long - term european study showed a 50% to 60% remission rate after 5 to 6 years of atd treatment . in japan , maintenance of a minimal dose of atds ( methimazole , 2.5 mg daily ) longer than 6 months after the normalization of tsh is recommended for a higher remission rate . however , a meta - analysis showed that the maintenance of atds longer than 18 months did not improve the remission rate in adults . atds are discontinued after the normalization of both serum tsh and trab by 60% to 70% of kta members . about 30% of respondents answered that they use atds for a fixed duration , most frequently for 12 to 24 months . in case of the recurrence after atd treatment , 46.9% ( 60/128 ) of kta members chose atds again for the treatment of graves disease ; while radioactive iodine and thyroidectomy were chosen by 48.4% ( 62/128 ) and 4.7% ( 6/128 ) of kta members , respectively . in korea , atds are the most preferred modality for retreatment as well as initial treatment , and the treatment duration of atds is longer compared with other countries . this therapy is well tolerated with rare complications , except for those related to ophthalmopathy . the kta report recommends that the use of methimazole or  blockades before and after i treatment may be considered in patients with severe thyrotoxicosis . the ata / aace guidelines remark that if given as pretreatment , methimazole should be discontinued 3 to 5 days before the administration of radioactive iodine , restarted 3 to 7 days later , and generally tapered over 4 to 6 weeks as thyroid function normalizes . in the kta survey , atds were used before and after i treatment by 56% and 43% of kta members , respectively . although the ata / aace guidelines do not recommend a special diet before i therapy , excessive iodine intake should be avoided for at least 7 days before treatment . because daily intake of iodine is more than 500 g in korea , the need for a special diet before i treatment should be validated in future studies . administering a fixed i activity or calculating the activity based on the size of the thyroid and its ability to trap iodine showed no difference in controlling hyperthyroidism by rendering the patient hypothyroid . the kta report recommends sufficient radiation ( 10 to 15 mci ) in a single dose . a pregnancy test should be obtained within 48 hours prior to treatment in any female with childbearing potential . after radioactive iodine therapy for graves disease , a follow - up thyroid function test should be performed within the first 1 to 2 months . if the patient remains thyrotoxic , biochemical monitoring should be continued at 4 to 6 week intervals . the kta report recommends retreatment with i when hyperthyroidism persists after 6 months following i therapy , or if there is minimal response 3 months after therapy . the kta report recommends near - total or total thyroidectomy as the procedure of choice . the optimal preparation for thyroidectomy , the monitoring and treatment strategy for the possible complications , and postoperative management , including t4 replacement , are described in the kta report . the kta consensus report was based on the ata / aace guidelines , and therefore , the recommendations are similar . however , the kta consensus report was also based on a survey of kta members and is therefore more suitable for clinical practice in korea . in addition , the recommendations in the kta consensus report are limited to the treatment of graves disease , because other causes of hyperthyroidism are relatively rare and the treatment of those diseases does not differ according to geographical area . considering the differences in the clinical practice patterns in the diagnosis and treatment of hyperthyroidism in korea compared with other countries , further studies investigating the characteristics and optimal treatment of hyperthyroidism in korean patients and the consequential revision of the kta report are needed .
hyperthyroidism is one of the causes of thyrotoxicosis and the most common cause of hyperthyroidism in korea is graves disease . 
 the diagnosis and treatment of graves disease are different according to geographical area . 
 recently , the american thyroid association and the american association of clinical endocrinologists suggested new management guidelines for hyperthyroidism . 
 however , these guidelines are different from clinical practice in korea and are difficult to apply . 
 therefore , the korean thyroid association ( kta ) conducted a survey of kta members regarding the diagnosis and treatment of hyperthyroidism , and reported the consensus on the management of hyperthyroidism . in this review 
 , we summarized the kta report on the contemporary practice patterns in the diagnosis and management of hyperthyroidism , and compared this report with guidelines from other countries .