title: Effect of the presence of remnant thyroid tissue on the serum thyroid hormone balance in thyroidectomized patients.
abstract: OBJECTIVE
  We and others recently reported that in total thyroidectomy (TT), serum triiodothyronine (T3) levels during levothyroxine (L-T4) therapy were low compared to the preoperative levels, suggesting that the presence of the thyroid tissue affects the balances of serum thyroid hormone levels. However, the effects of remnant thyroid tissue on these balances in thyroidectomized patients have not been established.
  
  
  METHODS
  We retrospectively studied 253 euthyroid patients with papillary thyroid carcinoma who underwent a TT or hemithyroidectomy (HT). We divided the cases into the TT+supplemental L-T4 (+L-T4) group (n=103); the HT+L-T4 group (n=56); and the HT-alone group (n=94). We compared the postoperative serum levels of free T4 (FT4) and free T3 (FT3) and the FT3/FT4 ratio in individual patients with those of controls matched by serum TSH levels.
  
  
  RESULTS
  The TT+L-T4 group had significantly higher FT4 (P<0.001), lower FT3 (P<0.01) and lower FT3/FT4 (P<0.001) levels compared to the controls. The HT+L-T4 group had FT4, FT3 and FT3/FT4 levels equivalent to those of the controls. The HT-alone group had significantly lower FT4 (P<0.01), equivalent FT3 (P=0.083), and significantly higher FT3/FT4 (P<0.001) ratios than the controls.
  
  
  CONCLUSIONS
  The presence of the remnant thyroid tissue was associated with different thyroid hormone balances in thyroidectomized patients, suggesting that T3 production by remnant thyroid tissue has a substantial effect on the maintenance of postoperative serum T3 levels.
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan ito02@kuma-h.or.jp.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ito
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Miyauchi
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Shino
authors.initials: S
authors.lastname: Kang
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Mako
authors.initials: M
authors.lastname: Hisakado
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Waka
authors.initials: W
authors.lastname: Yoshioka
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Akane
authors.initials: A
authors.lastname: Ide
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Kudo
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Eijun
authors.initials: E
authors.lastname: Nishihara
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Kihara
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miya
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Fukata
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Center for Excellence in Thyroid CareKuma Hospital, 8-2-35, Shimoyamate-Dori, Chuo-Ku, Kobe-City, Hyogo 650-0011, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Amino
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000601:surgery*; D002291:Carcinoma, Papillary; D015331:Cohort Studies; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000378:metabolism / Q000601:surgery*; D013964:Thyroid Neoplasms / Q000601:surgery*; D013965:Thyroidectomy / Q000009:adverse effects / Q000379:methods*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood* / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine