title: Development of subclinical hyperthyroidism due to Graves' disease in a hypothyroid woman who had undergone hemithyroidectomy for adenomatous goiter and radiotherapy for nasopharyngeal cancer.
abstract: A variety of thyroid disorders develop following external radiation to head and neck cancers. Hypothyroidism is the most common clinical consequence of the radiotherapy and lifelong thyroid hormone replacement is required in many cases. Patients who received both hemithyroidectomy and the external radiation to the neck are at especially high risk for permanent hypothyroidism. Here we report an unusual case with radiation-induced hypothyroidism who had undergone hemithyroidectomy for adenomatous goiter 8 years before the radiotherapy for nasopharyngeal cancer and subclinical hyperthyroidism due to Graves' disease developed during thyroxine replacement therapy. Thus subclinical hyperthyroidism due to Graves' disease can develop in patients with radiation-induced hypothyroidism even if they have undergone hemithyroidectomy for thyroid nodules. Therefore careful and periodic evaluation of thyroid function is required even on adequate thyroxine replacement therapy.
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Kouki
authors.initials: K
authors.lastname: Mori
authors.forename: Saeko
authors.initials: S
authors.lastname: Hoshikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ozaki
authors.forename: Sadayoshi
authors.initials: S
authors.lastname: Ito
authors.forename: Katsumi
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D000328:Adult; D002277:Carcinoma / Q000532:radiotherapy*; D005260:Female; D006044:Goiter, Nodular / Q000601:surgery*; D006111:Graves Disease / Q000150:complications / Q000188:drug therapy* / Q000601:surgery; D020249:Hormone Replacement Therapy / Q000009:adverse effects; D006801:Humans; D006980:Hyperthyroidism / Q000209:etiology* / Q000473:pathology; D007037:Hypothyroidism / Q000188:drug therapy / Q000209:etiology*; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries; D013965:Thyroidectomy / Q000009:adverse effects*; D013974:Thyroxine / Q000009:adverse effects / Q000627:therapeutic use
chemical_list: D013974:Thyroxine