title: Hypothyroidism after radiotherapy of head and neck cancer.
abstract: OBJECTIVE
  Hypothyroidism is not commonly considered as a complication of radiotherapy to the head and neck region. The purpose of this retrospective study was to determine the frequency of thyroid dysfunction in patients after radiotherapy, to compare thyroid hormone levels in irradiated patients with Control group and to predict development of thyroid hypofunction in time.
  
  
  METHODS
  Thyroid function was measured by means of thyroid stimulating hormone (TSH), free thyroxine (FT4) and free triiodthyronine (FT3) in 43 patients who had nonthyroid head-neck carcinomas treated by radiotherapy or radiotherapy in combination with other modalities. These data were compared with hormone levels of 40 Control group patients treated solely by surgery.
  
  
  RESULTS
  Hypothyroidism was found in 35% of irradiated patients. In comparison with Control group there were significant differences between TSH and FT4 levels, difference between FT3 levels was insignificant. A correlation between hormone levels and follow-up was detected.
  
  
  CONCLUSIONS
  Our results indicate that hypothyroidism is a frequent late side effect of radiotherapy to head and neck. Lifelong monitoring of thyroid function appears to be justified when radiotherapy is a part of treatment protocol.
authors.affiliation: Department of Maxillofacial Surgery (Head: Dr. Daniel Hrušák, Ph.D.), Charles University Hospital Pilsen, Alej Svobody 80, 304 60 Plzen, Czech Republic.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Bernát
authors.affiliation: Department of Maxillofacial Surgery (Head: Dr. Daniel Hrušák, Ph.D.), Charles University Hospital Pilsen, Alej Svobody 80, 304 60 Plzen, Czech Republic. Electronic address: hrusakd@fnplzen.cz.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hrušák
mesh_terms: D000368:Aged; D002277:Carcinoma / Q000532:radiotherapy / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000601:surgery; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology*; D007573:Jaw Neoplasms / Q000532:radiotherapy / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000532:radiotherapy / Q000601:surgery; D037981:Neck Dissection; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy; D009367:Neoplasm Staging; D018714:Radiotherapy, Adjuvant; D012189:Retrospective Studies; D013972:Thyrotropin / Q000032:analysis; D013974:Thyroxine / Q000032:analysis; D014284:Triiodothyronine / Q000032:analysis
chemical_list: D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine
keywords: Head and neck cancer; Hypothyroidism; Radiotherapy