title: A systematic review of the gonadal effects of therapeutic radioactive iodine in male thyroid cancer survivors.
abstract: BACKGROUND
  For patients with well-differentiated thyroid carcinoma (WDTC), the gonadal effects of radioactive iodine (RAI) therapy is an important consideration.
  
  
  OBJECTIVE
  We systematically reviewed the controlled studies examining the gonadal effects of RAI therapy in male WDTC survivors. We searched in nine electronic databases. All abstracts and papers were independently reviewed by two reviewers.
  
  
  RESULTS
  After reviewing 334 abstracts and 59 full-text papers, seven papers were included. In longitudinal studies examining the effect of single primary RAI dose activities of <or= 150 mCi, serum FSH and LH rose between months 2 and 6, with normalization by 18 months; serum testosterone did not significantly decrease. In one study, 18 months after RAI, the rates of elevated serum FSH were: 27% for 351-594 mCi and 81% for > 594 mCi. Cumulative RAI dose correlated with FSH measurements at long-term follow-up. In one study, approximately one in eight men experienced oligospermia 1 year after RAI therapy. Rates of infertility, pregnancy loss and offspring congenital malformation were not elevated, but studies were limited by small size and self-reported outcomes.
  
  
  CONCLUSIONS
  Abnormalities in testicular function are common within several months of a single therapeutic dose of RAI for WDTC. Biochemical abnormalities usually resolve within 18 months after administration of a single activity of < 150 mCi of RAI. The risk of persistent gonadal dysfunction is increased after repeated or high cumulative RAI activities. Controlled, prospective studies, with long-term follow-up, examining male gonadal and offspring effects of RAI therapy are needed.
authors.affiliation: Division of Endocrinology, Department of Medicine, University Health Network Toronto, Ontario, Canada. sawkaam@yahoo.com
authors.forename: Anna M
authors.initials: AM
authors.lastname: Sawka
authors.forename: Jane
authors.initials: J
authors.lastname: Lea
authors.forename: Bandar
authors.initials: B
authors.lastname: Alshehri
authors.forename: Sharon
authors.initials: S
authors.lastname: Straus
authors.forename: Richard W
authors.initials: RW
authors.lastname: Tsang
authors.forename: James D
authors.initials: JD
authors.lastname: Brierley
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
authors.forename: Lorne
authors.initials: L
authors.lastname: Rotstein
authors.forename: Amiram
authors.initials: A
authors.lastname: Gafni
authors.forename: Shereen
authors.initials: S
authors.lastname: Ezzat
authors.forename: David P
authors.initials: DP
authors.lastname: Goldstein
mesh_terms: D006801:Humans; D008297:Male; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000528:radiation effects; D007457:Iodine Radioisotopes / Q000494:pharmacology / Q000627:therapeutic use; D007986:Luteinizing Hormone / Q000097:blood / Q000528:radiation effects; D010902:Pituitary Gland / Q000528:radiation effects; D011829:Radiation Dosage; D013091:Spermatogenesis / Q000528:radiation effects; D013737:Testis / Q000503:physiopathology / Q000528:radiation effects; D013739:Testosterone / Q000097:blood / Q000528:radiation effects; D013964:Thyroid Neoplasms / Q000532:radiotherapy; D016896:Treatment Outcome
chemical_list: D005640:Follicle Stimulating Hormone; D007457:Iodine Radioisotopes; D007986:Luteinizing Hormone; D013739:Testosterone