title: Biochemical Markers Reflecting Thyroid Function in Athyreotic Patients on Levothyroxine Monotherapy.
abstract: Some investigators reported that among athyreotic patients on levothyroxine (LT4) monotherapy following total thyroidectomy, the patients with normal serum thyrotropin (TSH) levels had mildly low serum free triiodothyronine (fT3) levels, whereas the patients with mildly suppressed serum TSH levels had normal serum fT3 levels, and the patients with strongly suppressed serum TSH had elevated serum fT3 levels. The objective of the present study was to clarify which of these three patient groups is closer to their preoperative euthyroid condition.
  
  
  
  A total of 133 consecutive euthyroid patients with papillary thyroid carcinoma who underwent a total thyroidectomy were prospectively studied. The patients' serum levels of lipoproteins, sex hormone-binding globulin, and bone metabolic markers measured preoperatively were compared with the levels measured at postoperative LT4 therapy 12 months after the thyroidectomy.
  
  
  
  The postoperative serum sex hormone-binding globulin (p < 0.001) and bone alkaline phosphatase (p < 0.01) levels were significantly increased in the patients with strongly suppressed TSH levels (≤0.03 μIU/mL). The postoperative serum low-density lipoprotein cholesterol levels were significantly increased (p < 0.05), and the serum tartrate-resistant acid phosphatase-5b levels were significantly decreased (p < 0.05) in the patients with normal TSH (0.3 < TSH ≤5 μIU/mL). In the patients with mildly suppressed TSH (0.03 < TSH ≤0.3 μIU/mL) and fT3 levels equivalent to their preoperative levels, all metabolic markers remained equivalent to their preoperative levels.
  
  
  
  The serum biochemical markers of thyroid function in patients on LT4 following total thyroidectomy suggest that the patients with mildly suppressed TSH levels were closest to euthyroid, whereas those with normal TSH levels were mildly hypothyroid and those with strongly suppressed TSH levels were mildly hyperthyroid. These data may provide novel information on the management of patients following total thyroidectomy for thyroid cancer or benign thyroid disease.
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Ito
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Akira
authors.initials: A
authors.lastname: Miyauchi
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Mako
authors.initials: M
authors.lastname: Hisakado
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Waka
authors.initials: W
authors.lastname: Yoshioka
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Akane
authors.initials: A
authors.lastname: Ide
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Takumi
authors.initials: T
authors.lastname: Kudo
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Eijun
authors.initials: E
authors.lastname: Nishihara
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Minoru
authors.initials: M
authors.lastname: Kihara
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Akihiro
authors.initials: A
authors.lastname: Miya
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Shuji
authors.initials: S
authors.lastname: Fukata
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Mitsushige
authors.initials: M
authors.lastname: Nishikawa
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Nakamura
authors.affiliation: Center for Excellence in Thyroid Care , Kuma Hospital, Kobe, Japan .
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Amino
mesh_terms: D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D002291:Carcinoma, Papillary / Q000601:surgery*; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy / Q000209:etiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D000077273:Thyroid Cancer, Papillary; D013960:Thyroid Function Tests; D013964:Thyroid Neoplasms / Q000601:surgery*; D013965:Thyroidectomy / Q000009:adverse effects; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D012738:Sex Hormone-Binding Globulin; D014284:Triiodothyronine; D013972:Thyrotropin; C548267:ALPL protein, human; D000469:Alkaline Phosphatase; D013974:Thyroxine
keywords: athyreotic patients; levothyroxine; thyroidectomy; thyrotropin; triiodothyronine