title: Substituting Potassium Iodide for Methimazole as the Treatment for Graves' Disease During the First Trimester May Reduce the Incidence of Congenital Anomalies: A Retrospective Study at a Single Medical Institution in Japan.
abstract: BACKGROUND
  To control hyperthyroidism due to Graves' disease, antithyroid drugs should be administered. Several studies have shown that exposure to methimazole (MMI) during the first trimester of pregnancy increases the incidence of specific congenital anomalies that are collectively referred to as MMI embryopathy. Congenital anomalies associated with exposure to propylthiouracil (PTU) have also recently been reported.
  
  
  METHODS
  This study investigated whether substituting potassium iodide (KI) for MMI in the first trimester would result in a lower incidence of major congenital anomalies than continuing treatment with MMI alone. The cases of 283 women with Graves' disease (GD) were reviewed whose treatment was switched from MMI to KI in the first trimester (iodine group), as well as the cases of 1333 patients treated with MMI alone (MMI group) for comparison. Another major outcome of interest was the incidence of neonatal thyroid dysfunction. The subjects of the analysis of major congenital anomalies and neonatal thyroid dysfunction were live-born infants.
  
  
  RESULTS
  The incidence of major anomalies was 4/260 (1.53%) in the iodine group, which was significantly lower than the incidence of 47/1134 (4.14%) in the MMI group. Two neonates in the iodine group had anomalies consistent with MMI embryopathy (0.8%), as opposed to 18 neonates in the MMI group (1.6%). None of the neonates exposed to KI had thyroid dysfunction or goiter.
  
  
  CONCLUSIONS
  Substituting KI for MMI as a means of controlling hyperthyroidism in GD patients during the first trimester may reduce the incidence of congenital anomalies, at least in iodine-sufficient regions.
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Ai
authors.initials: A
authors.lastname: Yoshihara
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Jaeduk Yoshimura
authors.initials: JY
authors.lastname: Noh
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Natsuko
authors.initials: N
authors.lastname: Watanabe
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Koji
authors.initials: K
authors.lastname: Mukasa
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Hidemi
authors.initials: H
authors.lastname: Ohye
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Miho
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Masako
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Yo
authors.initials: Y
authors.lastname: Kunii
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Nami
authors.initials: N
authors.lastname: Suzuki
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kameda
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Kenji
authors.initials: K
authors.lastname: Iwaku
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Sakiko
authors.initials: S
authors.lastname: Kobayashi
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Kiminori
authors.initials: K
authors.lastname: Sugino
authors.affiliation: Department of Internal Medicine, Ito Hospital , Tokyo, Japan .
authors.forename: Koichi
authors.initials: K
authors.lastname: Ito
mesh_terms: D000014:Abnormalities, Drug-Induced / Q000453:epidemiology*; D000328:Adult; D013956:Antithyroid Agents / Q000009:adverse effects / Q000627:therapeutic use*; D057915:Drug Substitution; D005260:Female; D006111:Graves Disease / Q000097:blood / Q000188:drug therapy*; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008713:Methimazole / Q000009:adverse effects / Q000627:therapeutic use*; D011193:Potassium Iodide / Q000009:adverse effects / Q000627:therapeutic use*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000188:drug therapy*; D011261:Pregnancy Trimester, First; D012189:Retrospective Studies; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013956:Antithyroid Agents; D014284:Triiodothyronine; D011193:Potassium Iodide; D008713:Methimazole; D013972:Thyrotropin; D013974:Thyroxine