title: [Hypothyroidism after radiotherapy to the neck].
abstract: OBJECTIVE
  The purpose of this study was to investigate the incidence and possible predictors of hypothyroidism after radiotherapy to the neck, focusing on radiation dose-volume factors.
  
  
  METHODS
  Thyroid function was measured in 169 patients treated with radiation ports including the thyroid, between 1989 and 2000. Hypothyroidism was determined with an endpoint of elevated serum thyroid stimulating hormone(TSH) levels > 10.0 microU/ml. In 60 patients, radiation dose-volume factors were calculated; e.g., total volume of the thyroid, mean radiation dose to the thyroid, and %-volume of the thyroid which received radiation doses of no less than 10-70 Gy(V10-V70). The evaluated risk factors for hypothyroidism included these dose-volume factors, sex, age, primary disease, combined chemotherapy, and follow-up period.
  
  
  RESULTS
  Hypothyroidism was detected in 33 (19.5%) of the 169 patients. None of them had clinical symptoms of hypothyroidism. V10, V20, and V30 seemed to be possible predictors of hypothyroidism and had a significant impact on the peak level of serum TSH.
  
  
  CONCLUSIONS
  Radiation dose-volume factors of the thyroid seemed to correlate with the incidence of hypothyroidism, and V10, V20, and V30 had a significant impact on the peak level of serum TSH.
authors.affiliation: Division of Radiology, Kobe University Graduate School of Medicine.
authors.forename: Eisaku
authors.initials: E
authors.lastname: Yoden
authors.forename: Toshinori
authors.initials: T
authors.lastname: Soejima
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Maruta
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Demizu
authors.forename: Hideki
authors.initials: H
authors.lastname: Nishimura
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ejima
authors.forename: Ryohei
authors.initials: R
authors.lastname: Sasaki
authors.forename: Kazunari
authors.initials: K
authors.lastname: Yamada
authors.forename: Kazuro
authors.initials: K
authors.lastname: Sugimura
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000528:radiation effects*; D011878:Radiotherapy / Q000009:adverse effects