Optimizing 131I uptake after rhTSH stimulation in patients with nontoxic multinodular goiter: evidence from a prospective, randomized, double-blind study.
Prestimulation with recombinant human thyroid-stimulating hormone (rhTSH) augments radioiodine (131)I therapy for benign nontoxic multinodular goiter. The purpose of this study was to determine the optimal time interval between rhTSH and (131)I administration to enhance thyroid radioactive iodine uptake (RAIU).


METHODS
Patients were randomized, in a 2-factorial design, to receive either a 0.1-mg dose of rhTSH (n = 60) or placebo (n = 30) and to a time interval of 24, 48, or 72 h before (131)I administration. The rhTSH- or placebo-stimulated RAIU study was performed at 4 wk after a baseline RAIU assessment in a tertiary referral center at a university hospital. A total of 90 patients (78 women; median age, 52 y; range, 22-83 y) referred to (131)I therapy for symptomatic nontoxic goiter (median goiter volume, 63 mL; range, 25-464 mL) were included in the study. Change in thyroid RAIU was determined at 24 and 96 h after (131)I tracer administration.


RESULTS
In the placebo subgroups, RAIU did not change significantly from baseline. The mean (+/-SE) 24-h RAIU increased from 33.8% +/- 2.3% to 66.0% +/- 1.8% (111.2% increase) with a 24-h interval, from 36.8% +/- 2.1% to 64.6% +/- 2.7% (83.3% increase) with a 48-h interval, and from 33.0% +/- 2.7% to 49.6% +/- 2.5% (62.4% increase) with a 72-h interval. All within-group changes were highly significant (P < 0.001). The effect was negatively correlated with initial RAIU (r = -0.703, P < 0.001). The increase in 24- and 96-h RAIU was significantly higher in the rhTSH/24-h group than it was in the rhTSH/72-h group (P = 0.023 and 0.012, respectively) and insignificantly higher than in the rhTSH/48-h group (P = 0.37 and 0.26, respectively).


CONCLUSIONS
The effect of rhTSH on thyroid RAIU is most pronounced when administered 24 h before (131)I administration and declines with longer time intervals. Whether there is a similar time dependency for goiter reduction after rhTSH-stimulated (131)I-therapy remains to be clarified.
Fast
Søren
S
Department of Endocrinology and Metabolism, Odense University Hospital, Odense, Denmark. Soeren.Fast@ouh.regionsyddanmark.dk
Nielsen
Viveque Egsgaard
VE
Grupe
Peter
P
Bonnema
Steen Joop
SJ
Hegedüs
Laszlo
L
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D019317:Evidence-Based Medicine; D005260:Female; D006042:Goiter / Q000378:metabolism* / Q000532:radiotherapy*; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics* / Q000627:therapeutic use*; D008297:Male; D008657:Metabolic Clearance Rate / Q000187:drug effects; D008875:Middle Aged; D011446:Prospective Studies; D011994:Recombinant Proteins / Q000008:administration & dosage; D016037:Single-Blind Method; D013972:Thyrotropin / Q000008:administration & dosage* / Q000235:genetics; D016896:Treatment Outcome; D055815:Young Adult
D007457:Iodine Radioisotopes; D011994:Recombinant Proteins; D013972:Thyrotropin