title: Cutoff value of thyroid uptake of (99m)Tc-pertechnetate to discriminate between Graves' disease and painless thyroiditis: a single center retrospective study.
abstract: Thyroid uptake of (99m)Tc-pertechnetate is a useful way to determine the cause of thyrotoxicosis. In daily clinical practice, (99m)Tc-pertechnetate uptake is used to discriminate between Graves' disease and painless thyroiditis when clinical information is not enough to make the distinction. However, since the optimal cutoff value of (99m)Tc-pertechnetate uptake has not yet been elucidated, our aim was to determine this value. We recruited patients with thyrotoxicosis in whom (99m)Tc-pertechnetate uptake was measured in clinical settings between 2009 and 2013. Three experienced endocrinologists (who were blinded to the value of (99m)Tc-pertechnetate uptake and initial treatment) diagnosed the cause of thyrotoxicosis based on thyrotropin, free triiodothyronine, free thyroxine, and thyrotropin receptor antibody levels, and by ultrasound findings and using images of thyroid uptake of (99m)Tc-pertechnetate without the actual values. Ninety-four patients diagnosed as having Graves' disease or painless thyroiditis were finally included. According to the diagnosis, the optimal cutoff value of (99m)Tc-pertechnetate uptake was determined by receiver operating characteristics analysis. A cutoff value of 1.0% provided optimal sensitivity and specificity of 96.6% and 97.1%, respectively. Then, its validity was confirmed in 78 patients with confirmed Graves' disease or painless thyroiditis diagnosed at another institute. Applying this cutoff value to the patients with thyrotoxicosis revealed positive and negative predictive values for Graves' disease of 100% and 88.9%, respectively. In conclusion, a cutoff value for (99m)Tc-pertechnetate uptake of 1.0% was useful to discriminate between Graves' disease and painless thyroiditis.
authors.affiliation: Department of Metabolism & Endocrinology, Juntendo University Graduate School of Medicine, Tokyo, Japan.
authors.forename: Toyoyoshi
authors.initials: T
authors.lastname: Uchida
authors.forename: Ruriko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Kasai
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Onose
authors.forename: Koji
authors.initials: K
authors.lastname: Komiya
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Goto
authors.forename: Kageumi
authors.initials: K
authors.lastname: Takeno
authors.forename: Shinya
authors.initials: S
authors.lastname: Ishii
authors.forename: Junko
authors.initials: J
authors.lastname: Sato
authors.forename: Akira
authors.initials: A
authors.lastname: Honda
authors.forename: Yui
authors.initials: Y
authors.lastname: Kawano
authors.forename: Miwa
authors.initials: M
authors.lastname: Himuro
authors.forename: Emiko
authors.initials: E
authors.lastname: Yamada
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yamada
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Watada
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006111:Graves Disease / Q000175:diagnosis* / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013670:Sodium Pertechnetate Tc 99m / Q000493:pharmacokinetics*; D013960:Thyroid Function Tests / Q000592:standards*; D013961:Thyroid Gland / Q000378:metabolism*; D013966:Thyroiditis / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D013670:Sodium Pertechnetate Tc 99m