radioiodine therapy

A dosimetry study was performed on 26 patients with an auto nomous thyroid nodule and suppressed serum thyroid-stimulat ing hormone, to determine the dose to extranodular tissue when the nodule receives 300 Gy for 131Itherapy. Methods: Param eters of radioiodine turnover to be used in the dosimetry formula were separately obtained for the nodule and the contralateral lobe, as a measurable example of the extranodular tissue, using 55 MBq 123Iand a computer-assisted gamma camera. The biologic half-life of 123Iwas then converted into the effective half-life of 131I, and the volumes of the nodule and the lobe were obtained by scintigraphy or sonography. Results: The mean dose to the contralateral lobe from uptake and irradiation by the nodule was calculated to be 32 Gy, and that to the ipsilateral lobe was estimated to be 34 Gy. Conclusion: During radioiodine therapy for autonomous thyroid nodules, the extranodular tissue receives a higher dose than is generally assumed, which ex plains...

The aim of the present study was to assess whether 131I therapy for differentiated thyroid carcinoma (DTC) can affect endocrine testicular function. Serum follicle-stimulating hormone (FSH) and testosterone (T) concentrations were measured in 103 patients periodically submitted for radioiodine therapy for residual or metastatic disease. Mean follow-up was 93.7 +/- 54 mo (range 10-243 mo). Mean FSH values in 131I-treated patients tested after their last treatment were 15.3 +/- 9.9 mU/ml, significantly higher than those of 19 untreated patients (6.5 +/- 3.1 mU/ml). Considering the mean +3 s.d. FSH of untreated subjects as the upper limit of normal range, 36.8% of the patients had an abnormal increase in serum FSH. Longitudinal analysis performed in 21 patients showed that the behavior of FSH in response to 131I therapy was not universal. Six patients had no change or a slight increase in serum FSH after 131I administration; eleven patients had a transient increase above normal values ...

The aim of this retrospective study was the evaluation of a TcTUs (global technetium-99m pertechnetate thyroid uptake under suppression)-based approach in 370 patients with thyroid autonomy (Plummer's disease) treated by radioiodine therapy (RIT) under standardised conditions. The analysis included 370 patients (309 females, 61 males; mean age 64+/-11.6 years) treated for thyroid autonomy [unifocal (UFA), 36.8%; multifocal (MFA), 55.7%; disseminated (DISA), 7.6%]. During RIT all patients were under thyroid suppression (TSH< 0.1 microU/ml) and without thionamide treatment. Of the 370 patients, 73% (n=271) were manifestly hyperthyroid and 27% (n=99) subclinically hyperthyroid. A dosimetric study included uptake measurements 24, 48, and 96 h p.i. For dose estimation the Marinelli algorithm was used. For retrospective definition of the target volume we used the equation: Autonomous volume = TcTUs x 5. The spectrum of doses given in our patients ranged from 81 to 1933 Gy. After 18 months of follow-up, RIT was successful (TSH>0.5 microqU/l and/or TcTUs<1.6%) in 310 patients (84%). Of these patients, 291 (94%) were euthyroid (with or without L-thyroxine) and 19 (6%) subclinically hypothyroid (TSH>4 microU/ml). A dose of 350-450 Gy to the autonomous tissue resulted in a success rate of 97% in the UFA group and 81% in the MFA/DISA group. Decrease in total thyroid volume and TcTUs did not differ significantly between successfully treated patients and patients with persistent autonomy. Multivariate analysis of all 370 patients identified four independent factors that negatively influenced the therapeutic success: high pretherapeutic thyroid volume (P=0.0001; odds ratio: 1.017), high pretherapeutic TcTUs values (P=0.0001; odds ratio: 1.378), multifocal/disseminated autonomy (P=0.0056; odds ratio: 3.245) and low target dose (P=0.017; odds ratio: 0.997). It is concluded that the high success rate in the treatment of UFA indicates the concept of TcTUs-based RIT to be valid, but that in the therapy of MFA/DISA the target dose has to be corrected if the total thyroid volume exceeds a critical threshold.

Background: Chromosomal damage, as assessed by clastogenic factors (CFs) and micronuclei (MN) appearance, after radioiodine therapy of Graves’ disease has been reported. Objective and Methods: Our objective was to evaluate the effect of Ginkgo biloba extract (EGb 761) supplementation on the time course (up to 120 d) of CFs and MN appearance in lymphocytes from patients with Graves’ disease after iodine-131 (131I) therapy. Patients were randomly assigned to EGb 761 or placebo, in a blinded manner. Results: In the placebo group, MN increased early (P < 0.001) after 131I, peaking at the 21st day (P = 0.0003) and declining thereafter. In EGb 761-treated patients, MN increased early (P < 0.05), while returning toward baseline value thereafter. Therefore, mean MN increment was significantly higher in the placebo group as compared with EGb 761-treated patients (P < 0.01). Moreover, an early (P < 0.0001) and sustained (up to 35 d; P < 0.001) MN increase induced by CFs was obs...

Objective: To assess ovarian function in young women treated with radioiodine. Methods: The study was conducted on 50 women with thyroid carcinoma aged less than 40 years (mean, 29.8 years), with regular menstrual cycles and normal FSH levels prior to radioiodine therapy. ...

We proposed an alternative to a monoexponential model of radioiodine kinetics to obtain a more accurate estimate of absorbed doses to postsurgical thyroid remnants. We suggested that part of the difference between the predicted and the actually absorbed therapeutic doses of (131)I, usually explained by radiation damage of thyroid cells, can be attributed to errors resulting from inadequate sampling of data and oversimplified modeling. A standard monoexponential model and alternative biphasic model (incorporating both radioiodine uptake and clearance) were used on 2 sets of patient data to fit time-activity measurements after administration of diagnostic and therapeutic activities of radioiodine. One set of data consisted of 633 records of routine measurements, and the second set consisted of 71 prospectively collected records with measurements performed more frequently and for a longer time. The time-activity curves derived from the 2 models were used to calculate residence times fo...

Technical aspects and results of the dosimetric assessments of postoperative radioiodine ablation in the framework of an international, prospective, controlled, randomized, comparative study of the effectiveness of ablation therapy with 3.7 GBq (131)I in differentiated thyroid cancer after stimulation with recombinant human TSH (rhTSH) or by thyroid hormone withdrawal (THW) are presented. Sixty-three patients were randomized after thyroidectomy to either the THW or the rhTSH group. Scintigraphic neck images were acquired starting 48 h after radioiodine administration to assess biokinetics in the thyroid remnant. The activity in blood samples was quantified and data from whole-body probe measurements and scintigraphic whole-body scans were combined to deduce retention curves in blood and whole body, respectively. The absorbed dose to the blood was calculated using a modified approach based on the formalism of the MIRD Committee of the Society of Nuclear Medicine. The effective half-t...