Radioiodine therapy in hyperthyroid disease: poorer outcome in patients with high 24 hours radioiodine uptake.
OBJECTIVE
To evaluate the importance of 24 h radioiodine uptake (24 h RIU) for the outcome of radioiodine treatment of hyperthyroidism.


METHODS
Retrospective analysis of 72 patients who underwent radioiodine treatment for toxic goiter at our outpatient clinic [29 diffuse goiters (DG), 30 toxic multinodular goiters (TMG) and 13 toxic adenomas (TA)]. Thyroid status was determined by TSH, fT3 and fT4 levels, and outcome was rendered successful when hyperthyroidism was absent. Relation between low 24 h RIU (below median) or high 24 h RIU (above or equal to median) and outcome was evaluated.


RESULTS
Of patients with DG and low 24 h RIU, 15% remained hyperthyroid, as opposed to 56% of patients with DG and high 24 h RIU (P<0.05). Of patients with TMG and low 24 h RIU, none remained hyperthyroid, as opposed to 44% of patients with TMG and high 24 h RIU (P<0.01). Of patients with TA and low 24 h RIU, none remained hyperthyroid, as opposed to 43% of patients with TA and high 24 h RIU (NS, P = 0.19).


CONCLUSIONS
In patients with hyperthyroid disease treated with radioiodine the outcome is poorer for patients with high 24 h RIU compared with low 24 h RIU measured prior to treatment when the radioiodine dose is calculated on the basis of 24 h RIU.
Kristoffersen
Ulrik Sloth
US
Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
Hesse
Birger
B
Rasmussen
Ase Krogh
AK
Kjaer
Andreas
A
D004307:Dose-Response Relationship, Radiation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000532:radiotherapy*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013960:Thyroid Function Tests; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood
D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine