The effect of radioactive iodine therapy on urine sterilization in patients with differentiated thyroid cancer

Abstract

Background: Urinary tract infection is the most common infection which necessitates antibiotics prescription. On the other hand, the appearance of antimicrobial resistance is one of the major health problems due to irrational antibiotic administration. Radio iodine therapy, using I-131 following thyroidectomy, is the standard treatment for the patients with differentiated thyroid cancer (DTC). After the consumption of radioactive iodine, it mainly excretes through the urinary system. This study is aimed to assess the effect of radioactive iodine (I-131) in the eradication of asymptomatic bacteriuria (ABU). Methods: Between September 2015 and May 2017, all the patients with DTC who were hospitalized to Nuclear Medicine Department for radio iodine ablation therapy were enrolled in the study. Urine analysis and culture were done for all the patients before iodine administration. If the result of the urine assessment was positive for the infection, urine culture repeated 1 week later and compare with pre-treatment results. Results: Of 182 patients, 10 cases had abnormal urine culture results. Five patients had CFU under 100,000, therefore was not considered as ABU; however, two of these patients had sterile urine after the treatment. Our only positive case had post treatment sterile urine. Conclusion: Considering radioactive iodine urine excretion, high radiation induced by radioactive iodine that passes through urinary tract may eradicate infection of genitourinary system