title: Endocrine intervention during irradiation does not prevent damage to the thyroid gland.
abstract: Radiation to the head-neck region may damage the thyroid gland, leading to hypothyroidism or thyroid carcinoma. Outcomes of radiation protection by lowering plasma thyroid-stimulating hormone (TSH) have thus far been ambiguous. Our aim was to evaluate the radioprotective effect of inhibiting the thyroid gland's activity during x-radiation. For this purpose, of 80 5-week old Wistar rats, 64 received cervical irradiation with 15 Gy (single dose). During irradiation, endocrine intervention was done, using thyroxine (T(4)), T(4) plus iodine, or iodine alone compared to placebo. During the endocrine interventions and follow-up, TSH and T(4) concentrations were measured periodically. Histologic examination of thyroid, pituitary gland, or the hypothalamus and any suspect lymph nodes, lungs, and liver was performed after 6 and 54 weeks. It was found that during the endocrine intervention, plasma levels of TSH were lower in rats given T(4) and higher in rats given iodine. After 6 and 54 weeks, no significant reduction in hypothyroidism or thyroid carcinoma was found between the different groups of rats given any endocrine intervention or no intervention. In conclusion, the administration of T(4), iodine or the combination during x-irradiation does not protect against radiation-induced thyroid damage.
authors.affiliation: Department of Pediatric Endocrinology, Emma Children's Hospital, Academic Medical Centre, 1100 DE Amsterdam, The Netherlands. h.m.vansanten@amc.uva.nl
authors.forename: H M
authors.initials: HM
authors.lastname: van Santen
authors.forename: J E
authors.initials: JE
authors.lastname: van Dijk
authors.forename: H
authors.initials: H
authors.lastname: Rodermond
authors.forename: F
authors.initials: F
authors.lastname: Vansenne
authors.forename: E
authors.initials: E
authors.lastname: Endert
authors.forename: J J M
authors.initials: JJ
authors.lastname: de Vijlder
authors.forename: J
authors.initials: J
authors.lastname: Haveman
authors.forename: T
authors.initials: T
authors.lastname: Vulsma
mesh_terms: D000818:Animals; D004338:Drug Combinations; D005500:Follow-Up Studies; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000517:prevention & control; D011835:Radiation Protection / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D012974:Sodium Iodide / Q000627:therapeutic use; D013961:Thyroid Gland / Q000473:pathology / Q000502:physiology / Q000528:radiation effects*; D013964:Thyroid Neoplasms / Q000517:prevention & control; D013972:Thyrotropin / Q000037:antagonists & inhibitors* / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use
chemical_list: D004338:Drug Combinations; D013972:Thyrotropin; D012974:Sodium Iodide; D013974:Thyroxine