Overall, the rhTSH primed (131)I therapy protocol was found to be feasible and a good alternative to the thyroid hormone withdrawal protocol in patients with metastatic DTC. The lesional dosimetry findings need to be further examined in subsequent studies. The rhTSH primed pretreatment scan at 24 h after diagnostic dose is suboptimal to determine whether a metastatic lesion concentrates (131)I and the posttreatment scan is important for the correct impression.

The objective of the study was to make a quantitative comparison of 24-h thyroid uptake calculated by γ camera-based and thyroid uptake probe-based methods after administration of a diagnostic 131 I capsule in patients with benign thyroid disorders. Methods: The study group comprised 66 patients, of whom 26 were male (28-67 y old) and 40 female (20-65 y old). These patients had benign thyroid disorders (primarily hyperthyroidism [thyrotoxicosis]), most of whom had been referred for evaluation before radioiodine treatment. 131 I (25 μCi [925 MBq]) was administered, and 24-h thyroid uptake was calculated using a probe-based method and a camera-based method with a medium-energy parallel-hole collimator. The paired t test was used to check the variation in values obtained by these 2 methodologies. Result: Of the 66 patients included in this study, 45 had clinical thyrotoxicosis and 21 had nonthyrotoxic multinodular goiter. In the group with thyrotoxicosis, neck uptake ranged from 40.13% to 97.1% by the probe-based method and 36.89% to 95.9% by the camera-based method. In the group with clinically nonthyrotoxic goiter, neck uptake ranged from 1.4% to 38.4% by the probe-based method and 0.6% to 34.8% by the camera-based method. Paired t testing was performed on both groups of patients, and P values were less than 0.05, showing good agreement within the 2 groups of data. Conclusion: The camera-based method is a good substitute for the probe-based method; though not producing identical results, the former could be used to derive useful quantitative information on thyroid function.

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The results of this study, carried out in different groups of patients with hyperthyroidism, suggested that a short course of lithium is safe and could be beneficial for hyperthyroid patients considered for RAI therapy as it increased the RAI retention in thyroid, and thus had the potential to increase the effect of RAI therapy. Alternatively, it is proposed that lithium priming could help reduce the dose of RAI administered without compromising on therapeutic efficacy, with possible potential implications for cost reduction, radiation safety precautions, and lowered radiation dose to nontarget organs.