Influence of hydrochlorothiazide on urinary excretion of radioiodine in patients with differentiated thyroid cancer

Abstract

© 2015, Editura Academiei Romane. All rights reserved. Objective. After total thyroidectomy, radioiodine (131I) treatment is a usual treatment in patients with differentiated thyroid cancer (DTC). Since most of ingested131I is excreted by the kidneys, one of the procedures for enhancement of131I excretion from the body is the use of diuretics. The aim of study was to investigate the effect of hydrochlorothiazide (HCTZ) administration on the excretion of131I in the urine in patients with DTC treated with131I. Design. Study included 90 patients with DTC, normal renal function and low131I uptake in the thyroid gland region. Patients were divided into two groups: the group taking HCTZ and the control group. All patients underwent whole-body measurements of the radioactivity of131I in the urine and in blood samples. Results. Blood radioactivity was significantly higher in the HCTZ group as compared to the control group (16380.89 vs. 11731.61cpm/mL/GBq; P=0.007). The residual radioactivity in the body and the exposed dose were higher in patients taking HCTZ (71.61 vs. 60.70MBq/GBq and 7.05% vs. 6.14%) but this difference was not significant. During the first 36h from131I administration the patients taking HCTZ excreted a higher percentage of the131I than the controls (65.45±12.12% vs. 62.21±11.25%, P=0.032). During the second part of the hospitalization (36-72h) the urinary excretion as reversed, so after 72h patients taking HCT excreted less131I than controls, however, this difference was not significant (P=0.084; 76.54±10.16% vs. 83.81±13.46%). Conclusions. HCTZ given as additional treatment decreases urinary excretion of131I as and should not be administered in patients under131I treatment for DTC.