Incidence of Radioiodine-induced Gastritis and the Dosage of I-131 Ablation for Differentiated Thyroid Cancer: Results of a Multi-year Analysis

257 Objectives One of the potential side effects of radioactive iodine ablation with I-131 (RAI) in differential thyroid cancer (DTC) is radiation gastritis, which is caused by irradiation of the gastric mucosa from I-131. Our aim was to determine if the incidence of radioiodine-induced gastritis (RIG) depends upon the dosage of I-131 dispensed to the patient. Methods From 2005 to 2014, all patients undergoing RAI for DTC were questioned regarding gastritis-related symptoms (nausea, vomiting, etc.) upon their visit for the post-ablation I-131 whole-body scan one week after the RAI. Excluded from this study were patients with known gastric and gastroesophageal disorders, such as peptic ulcer disease, gastroesophageal reflux, and diabetic gastroparesis. We also excluded patients with prior gastric surgery. The remaining patients were classified into 3 groups according to the I-131 dosage; 100mCi (N=257), 150mCi (N=196) and 200mCI (N=105). Results Of the 257 patients receiving 100mCi of I-131, 178 (68.26%) complained of gastritis symptoms, compared to 139 of the 196 patients (70.92%) receiving 150mCi, and 77 of the 105 patients who received 200mCi (73.33%) of I-131. There was no association between the incidence of RIG and the dosage of I-131 dispensed, according to chi-square analysis (0.421), and a p value of 0.81. Conclusions Over a 10-year interval involving a total of 558 patients undergoing RAI for DTC, there was no proportional relationship between the dosage of I-131 administered and the incidence of RIG, contrary to what one might expect. A patient receiving 200mCi is no more likely to develop RIG as one receiving 100mCi.