Remission After Potassium Iodide Therapy in Patients With Graves' Hyperthyroidism Exhibiting Thionamide-Associated Side Effects

• Published in: The journal of clinical endocrinology and metabolism Vol. 99; no. 11; pp. 3995 - 4002
• Main Authors: Okamura, Ken, Sato, Kaori, Fujikawa, Megumi, Bandai, Sachiko, Ikenoue, Hiroshi, Kitazono, Takanari
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.11.2014; Copyright by The Endocrine Society
• Subjects: Adolescent; Adult; Aged; Antithyroid Agents - adverse effects; Antithyroid Agents - therapeutic use; Biological and medical sciences; Drug Administration Schedule; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Graves Disease - drug therapy; Humans; Male; Medical sciences; Methimazole - adverse effects; Methimazole - therapeutic use; Middle Aged; Non tumoral diseases. Target tissue resistance. Benign neoplasms; Potassium Iodide - therapeutic use; Propylthiouracil - adverse effects; Propylthiouracil - therapeutic use; Remission Induction - methods; Retreatment; Thyroid. Thyroid axis (diseases); Treatment Outcome; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Young Adult; Endocrinopathy; Human; Obesity; Nutrition; Hyperthyroidism; Thyroid diseases; Nutrition disorder; Patient; Metabolic diseases; Treatment; Secondary effect; Remission; Potassium iodide; Endocrinology; Nutritional status
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2013-4466

Context: Thionamides have various side effects. Objective: The effectiveness of potassium iodide (KI) was evaluated in hyperthyroid patients who experienced side effects to thionamides. Design and Setting: An observational study was conducted at an academic medical center. Patients: Among 1388 patients with Graves' hyperthyroidism treated with thionamides, 204 (14.7%) exhibited side effects, and 44 were treated with KI and followed for 17.6 (median; range, 8.6–28.4) years. Main Outcome Measures: The primary endpoint was the initial response to KI, and the secondary endpoint was the long-term prognosis. Results: The conditions of 29 (65.9%) of the 44 patients were well controlled with KI alone (10–400 mg/d) (A group), and 17 (38.6%) patients went into remission after 7.4 (1.9–23.0) years. The conditions of 15 (34.1%) patients were not controlled with KI alone (B group), even at a high dose (100–750 mg/d), but seven patients (15.9%) were controlled with a combination of KI and low-dose thionamides, resulting in remission after 7.2 (2.8–10.8) years. The initial parameters did not predict the response to KI or long-term prognosis. However, remission occurred in 70.8% of the patients treated with less than 200 mg of KI, compared with 35.0% of the patients who required 200 mg or more of KI (P < .05). Conclusions: Among hyperthyroid patients with thionamide-associated side effects, KI therapy was effective in two-thirds of cases, and about 40% of the patients experienced remission after KI therapy alone. The chance of remission was small among the patients refractory to KI.