title: Inappropriate Suppression of Thyrotropin Concentrations in Young Patients with Thyroid Nodules Including Thyroid Cancer: The Fukushima Health Management Survey.
abstract: Serum thyroid hormone concentration is regulated through the hypothalamic-pituitary-thyroid axis. This study aimed to clarify the relationships between thyroid hormone regulation and ultrasonographic findings in subjects with thyroid nodules detected during thyroid ultrasound examination for the Fukushima Health Management Survey.
  
  
  
  As of October 31, 2014, a total of 296,253 subjects, who had been living in Fukushima Prefecture at the time of the Fukushima nuclear power plant accident and were aged ≤18 years on March 11, 2011, participated in two concurrent screening programs. In the primary screening, thyroid nodules were detected in 2241 subjects. A secondary confirmatory thyroid ultrasound examination and blood sampling for thyroid function tests were performed on 2004 subjects. The subjects were reassessed and classified into disease-free subjects (Group 1), subjects with cysts only (Group 2), subjects with nodules (Group 3), and subjects with malignancy or suspected malignancy (Group 4). Serum concentrations of free triiodothyronine (fT3), free thyroxine (fT4), thyrotropin (TSH), thyroglobulin, and the fT3/fT4 ratio were classified according to the diagnoses.
  
  
  
  Inverse relationships between age and log TSH values (Spearman's correlation r = -0.311, p = 0.015), serum fT3 concentration (r = -0.688, p < 0.001), and the fT3/fT4 ratio (r = -0.520, p < 0.001) were observed in Group 1. When analysis of covariance with Bonferroni post hoc comparisons was used in the four groups, the log TSH values were significantly lower in both Group 3 and Group 4 compared with Group 1 and Group 2 after correcting for age (p < 0.001; Group 1 vs. Group 3, p = 0.016; Group 1 vs. Group 4, p = 0.022; Group 2 vs. Group 3, p = 0.001; Group 2 vs. Group 4, p = 0.008). However, no significant differences were observed between the four groups regarding levels of fT3, fT4, fT3/fT4 ratio, and thyroglobulin (p = 0.304, 0.340, 0.208, and 0.583, respectively).
  
  
  
  TSH suppression can be present in response to illness, including thyroid nodules, in young subjects. Low TSH levels may be associated with the finding of papillary thyroid cancer as well as with thyroid nodules in children and adolescents.
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Satoru
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: 2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Izumi
authors.initials: I
authors.lastname: Nakamura
authors.affiliation: 2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Satoshi
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: 2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Chiyo
authors.initials: C
authors.lastname: Ohkouchi
authors.affiliation: 2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Mizunuma
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|3 Department of Radiation Health Management, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Sanae
authors.initials: S
authors.lastname: Midorikawa
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Fukushima
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|4 Department of Laboratory Medicine, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ito
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|4 Department of Laboratory Medicine, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shimura
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|5 Department of Epidemiology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ohira
authors.affiliation: 6 Department of Otolaryngology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsuzuka
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|3 Department of Radiation Health Management, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Akira
authors.initials: A
authors.lastname: Ohtsuru
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .
authors.forename: Masafumi
authors.initials: M
authors.lastname: Abe
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yamashita
authors.affiliation: 1 Radiation Medical Science Center for the Fukushima Health Management Survey, Fukushima Medical University , Fukushima, Japan .|2 Department of Thyroid and Endocrinology, School of Medicine, Fukushima Medical University , Fukushima, Japan .
authors.forename: Shinichi
authors.initials: S
authors.lastname: Suzuki
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002648:Child; D002675:Child, Preschool; D006801:Humans; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000000981:diagnostic imaging; D016606:Thyroid Nodule / Q000097:blood* / Q000000981:diagnostic imaging; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014463:Ultrasonography; D055815:Young Adult
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine