ORIGINAL ARTICLES   

Panminerva Medica 2000 December;42(4):241-5

Copyright © 2009 EDIZIONI MINERVA MEDICA

lingua: Inglese

One-year follow-up of Graves’ disease treatment by four different protocols of radioiodine administration

Calegaro J. U. M., De Freitas Gomes E., Bae S. H., Ulyssea R., Casulari L. A.

From the Unit of Nuclear Medicine Hospital de Base do Distrito Federal *Unit of Endocrinology, Brasilia University Hospital and Unit of Neurosurgery, Hospital de Base do Distrito Federal Brasília - DF, Brazil

Background. Studies ­have ­been per­formed in ­order to ­assess a treat­ment ­with 131I ­able to ­induce a con­sis­tent improve­ment in Graves’ hyper­thyr­oi­dism.
Methods. Experimental ­design: For ­this pur­pose, ­four dif­fer­ent pro­to­cols ­based on ­four dif­fer­ent dos­es of radio­io­dine ­have ­been test­ed in Graves’ dis­ease ­patients. Patients nev­er sub­mit­ted pre­vi­ous­ly to anti­thy­roid ­drug treat­ment ­were giv­en 1 mCi/ 10 gm of the esti­mat­ed thy­roid ­weight (­group I; n=50). Group II (n=48) includ­ed ­patients not pre­vi­ous­ly treat­ed ­with anti­thy­roid ­drugs and who ­were giv­en dos­es of ­iodine ­based on a for­mu­la tak­ing ­into ­account the ­rate of thy­roid ­iodine ­uptake, i.e. 131I ­dose = µCi/gm of the esti­mat­ed thy­roid ­weight × 100/24 hrs 131I ­uptake (%). Patients pre­vi­ous­ly sub­mit­ted to anti­thy­roid ­drug ther­a­py ­were treat­ed ­with radio­io­dine ­whose ­dose was cal­cu­lat­ed accord­ing to the for­mu­la report­ed ­above, but the ­dose was ­increased in ­order to over­come the pos­sible resis­tance of ­this ­kind of ­patients to the ­effect of 131I. One ­group (group III; n=24) ­received the cal­cu­lat­ed ­dose ­plus 1 µCi/gm of the esti­mat­ed thy­roid ­weight. Finally, ­group IV (n=27) ­received the cal­cu­lat­ed ­dose plus 0.25 µCi/gm of the esti­mat­ed thy­roid ­weight.
Results. The anal­y­sis of the ­patients one ­year lat­er dem­on­strat­ed ­that ­groups I and II pre­sent­ed the high­er per­cent of euthyr­oid ­patients (60% and 58%, respec­tive­ly) fol­lowed by ­group IV (37%) and ­group III (29.2%). The per­cent of ­patients ­still exhib­it­ing hyper­thyr­oi­dism was 28% in ­group I, 26% in ­group IV, 12.5% in ­group III and 8.3% in ­group II. The high­est num­ber of hypo­thy­roid ­patients was ­present in ­group III (58.3%) fol­lowed by ­group IV (37 %), ­group II (33.3%) and ­group I (12 %).
Conclusions. The ­data ­here pre­sent­ed sug­gest ­that pro­to­cols I and II ­based on rel­a­tive­ly low dos­es of radio­io­dine are rath­er effec­tive in reduc­ing Graves’ hyper­thyr­oi­dism in ­patients not sub­mit­ted pre­vi­ous­ly to anti­thy­roid ­drug ther­a­py. The ­most sat­is­fac­to­ry ther­a­py ­seems ­that uti­lized in pro­to­col II, ­that in ­front of a ­fair ­amount of euthyr­oid ­patients (58.3%) ­presents a ­very low num­ber of sub­jects ­still hyper­thyr­oid (8.3%). However, the num­ber of ­patients who ­became hypo­thy­roid (33.3%) as a con­se­quence of the ther­a­py was too ­high. Hopefully, a bet­ter ­design of the pro­to­col ­will ­reduce ­this fig­ure. The ­high inci­dence of hyper­thyr­oi­dism ­observed in ­groups III and IV sub­mit­ted to a ther­a­py ­with 131I dos­es con­sis­tent­ly high­er ­than ­those uti­lized in ­groups I and II ­seems to con­firm the hypoth­e­sis ­that hyper­thyr­oid sub­jects sub­mit­ted to a ther­a­py ­with anti­thy­roid ­drugs ­become rath­er resist­ant to a radio­io­dine treat­ment.