RADIOBIOLOGY 

The Quarterly Journal of Nuclear Medicine 2000 December;44(4):333-9

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Health effects of therapeutic use of 131I in hy-perthyroidism

Pauwels E. K. J., Smit J. W. A. *, Slats A., Bourguignon M. **, Overbeek F.

From the Division of Nuclear Medicine Department of Radiology and *Department of Endocrinology Leiden University Medical Centre, Leiden, The Netherlands **Office de Protection contre le Rayonnements Ionisant Le Vésinet, France

Since 1942, ther­a­py ­with radio­io­dine (Na131I) has ­gained a ­major ­role in the treat­ment of ­benign thy­roid dis­or­ders, not­ably hyper­thyr­oi­dism ­caused by Graves’ dis­ease or tox­ic mul­ti­nod­u­lar goi­ter. The ­very ­large ­series of ­patients treat­ed so far ­offer the oppor­tu­nity for an assess­ment of ­both ­benign and malig­nant ­side ­effects. Hyperthyroidism is some­times ­observed ­after radio­io­dine ther­a­py due to radi­a­tion ­induced thy­roid hor­mone or by an immu­no­log­i­cal mech­a­nism. Despite the numer­ous ­attempts to ­design dos­age sched­ules aim­ing at euthyr­oi­dism, hypo­thy­roid­ism ­occurs in the major­ity of ­patients through­out ­life. Transient hypo­thy­roid­ism may be ­observed with­in the ­first ­year ­after ther­a­py and is ­caused by an immu­no­log­i­cal mech­a­nism. Radioiodine ther­a­py in Graves’ dis­ease may ­induce or wors­en ophthal­mop­a­thy, ­which can be pre­vent­ed by ster­oids effec­tive­ly. Hypoparathyroidism and hyper­pa­rath­yr­oi­dism ­have ­been report­ed ­after radio­io­dine ther­a­py but prob­ably do not ­exceed the nor­mal inci­dence. Sialitis is com­mon­ly ­observed but most­ly in ­patients treat­ed ­with radio­io­dine for thy­roid can­cer. There are no indi­ca­tions for induc­tion of genetic abnor­mal­ities ­after radio­io­dine ther­a­py ­although no def­i­nite con­clu­sion can be ­reached. Much atten­tion has ­been ­paid to malig­nant dis­ease. In ­very ­large ­series, no ­effects of radio­io­dine ther­a­py on sur­vi­val ­have ­been ­observed. Some stud­ies ­report an ­increased rel­a­tive ­risk for cer­tain ­types of can­cer (not­ably thy­roid can­cer, stom­ach can­cer, blad­der and kid­ney can­cer or hemat­o­log­i­cal malig­nan­cies). However, ­these obser­va­tions ­were not con­firmed by oth­er ­large stud­ies, so ­that no def­i­nite con­clu­sion ­with ­respect to ­risk for cer­tain ­types of malig­nant dis­ease can be ­drawn. However, radio­io­dine ther­a­py for ­benign thy­roid dis­or­ders has gen­er­al­ly ­been con­sid­ered ­safe and with­out ­major ­side ­effects, hypo­thy­roid­ism ­being the ­most fre­quent one.