BACKGROUND: The utility of thyroglobulin (Tg) in the follow-up of differentiated thyroid cancer (DTC) patients has been well-documented. Although third-generation immunoassays have improved accuracy, limitations persist (interfering anti-Tg antibodies and measurement variability). Evolving treatment strategies require a reevaluation of Tg thresholds for optimal patient management.
OBJECTIVE: To assess the performance of serum Tg testing in two populations: patients receiving total thyroidectomy and radioiodine remnant ablation (RRA), or treated with thyroidectomy alone.
METHODS: Prospective observational study. Setting. Centers contributing to the Italian Thyroid Cancer Observatory (ITCO) database.
METHODS: We included 540 patients with 5 years of follow-up and negative anti-Tg antibodies.
METHODS: Serum Tg levels assessed at 1-year follow-up visit.
METHODS: Detection of structural disease within 5 years of follow-up.
RESULTS: After excluding 26 patients with structural disease detected at any time point, the median Tg did not differ between patients treated with or without radioiodine. Data-driven Tg thresholds were established based on the 97th percentile of Tg levels in disease-free individuals: 1.97 ng/mL for patients undergoing thyroidectomy alone (lower than proposed by the MSKCC protocol and ESMO Guidelines, yet demonstrating good predictive ability, with a negative predictive value (NPV) of 98%) and 0.84 ng/mL for patients receiving post-surgical RRA. High sensitivity and NPV supported the potential of these thresholds in excluding structural disease.
CONCLUSIONS: This real-world study provides evidence for the continued reliability of 1-year serum Tg levels. The data-driven Tg thresholds proposed offer valuable insights for clinical decision-making in patients undergoing total thyroidectomy with or without RRA.

OBJECTIVE: Collecting venous blood samples from patients post administration of high therapeutic activities results in radiation exposure to staff collecting the blood. This study investigated the use of finger-tip capillary-blood collection as an alternative to the venous-blood collection method recommended by the European Association of Nuclear Medicine (EANM) dosimetry protocol for quantifying 131I concentration in the critical organ after therapeutic dose of 131I.
METHODS: The study included differentiated thyroid cancer patients referred to a thyroid cancer centre at St James\'s Hospital, Ireland, for therapeutic and diagnostic oral administration of 131I. The 15 patients recruited for this study provided 30 venous and capillary paired-blood samples. The activity concentration of the blood samples was compared between the type of blood (venous vs capillary) and the geometry/volume of the blood (1.0 ml versus 0.03 ml). Other variables were also investigated including administered activities, dose to staff performing the sampling, duration of sampling and time since administration.
RESULTS: Blood samples were taken at 2.0-91.9 h post administration using 0.2 ± 0.0 GBq (n = 2) or 4.0 ± 0.1 GBq (n = 28) 131I activities. There was no significant difference found between different blood sampling types (-1.0 ± 4.3 %, p = 0.223), different blood volumes (-3.2 ± 10.0 %, p = 0.070), or between their combination. No significant correlation was found between the percentage differences and investigated parameters.
CONCLUSIONS: A high degree of accuracy was achieved with blood radioactivity quantified using capillary blood collection using the finger-prick method. Further validation of the method would be required prior to implementation, to investigate patient specific factors which may affect accuracy.

BACKGROUND: The high doses of radioiodine-131 (131I) and, subsequently, the high radioactive burden for dog and environment warrants optimization of 131I therapy in dogs with thyroid carcinoma (TC).
OBJECTIVE: To evaluate the effect of a revised protocol with recombinant human thyroid stimulating hormone (rhTSH) on tumor radioactive iodine uptake (RAIU) in dogs with TC.
METHODS: Nine client-owned dogs diagnosed with TC.
METHODS: A prospective cross-over study in which tumor RAIU was calculated and compared at 8 hours (8h-RAIU) and 24 hours (24h-RAIU) after injection of radioactive iodine-123 (123I), once with and once without rhTSH (ie, 250 μg, IM, 24 and 12 hours before 123I) in each dog. Simultaneously, serum total thyroxine (TT4) and TSH were measured at baseline (T0), and 6 (T6), 12 (T12), 24 (T24), and 48 hours (T48) after the first rhTSH administration.
RESULTS: Tumor RAIU was significantly higher at 24 hours with rhTSH compared to no rhTSH (mean difference = 8.85%, 95% CI of [1.56; 16.14]; P = .03), while this was non-significant at 8 hours (mean difference = 4.54%, 95% CI of [0.35; 8.73]; P = .05). A significant change of serum TT4 (median difference T24 - T0 = 35.86 nmol/L, interquartile range [IQR] = 15.74 nmol/L) and TSH (median difference T24 - T0 = 1.20 ng/mL, IQR = 1.55 ng/mL) concentrations occurred after administration of rhTSH (P < .001).
CONCLUSIONS: Recombinant human TSH could optimize 131I treatment in dogs with TC by increasing tumor RAIU and thus 131I treatment efficacy.

UNASSIGNED: The normal reference values for the thyroid uptake of radioactive iodine and Tc-99m pertechnetate in euthyroid patients vary by geographical location as well as the amount of iodine intake in the diet. The present study examines the normal reference values for thyroid uptake of Tc-99m pertechnetate in the North of Iran.
UNASSIGNED: The participants of this study were 64 patients (all over 20 years of age) who had referred to the Nuclear Medicine Center of the Shahid Beheshti Hospital for thyroid scan over the period between March 2018 and May 2020. It is worth mentioning that relying on laboratory test results, only patients with normal thyroid function were included in this cross-sectional study.
UNASSIGNED: The median, the 5th and 95th percentiles and thyroid uptake range of 99mTc-pertechnetate in euthyroid patients were 0.9, 0.6 to 1.8% and 0.54 - 1.80%, respectively.
UNASSIGNED: The percentage of uptake in the thyroid gland in each geographical area varies based on race and diet content, so it is necessary to determine the percentage of uptake in each specific region and even check it periodically.

The radioiodine scan is a non-invasive imaging modality that allows for the visualization of functional thyroid tissue, as well as the detection of thyroid cancer remnants and metastases. However, it is important to note that radioiodine uptake is not exclusive to thyroid tissue and can lead to false-positive results if unexpected uptake occurs in non-thyroidal tissue. Herein, we present a case of a patient diagnosed with thyroid carcinoma, whose radioiodine scan demonstrated increased uptake in the thorax, corresponding to a lung carcinoma.

UNASSIGNED: Molecular imaging of thyroid and parathyroid diseases has changed in recent years due to the introduction of new radiopharmaceuticals and new imaging techniques. Accordingly, we provided an clinicians-oriented overview of such techniques and their indications.
UNASSIGNED: A review of the literature was performed in the PubMed, Web of Science, and Scopus without time or language restrictions through the use of one or more fitting search criteria and terms as well as through screening of references in relevant selected papers. Literature up to and including December 2023 was included. Screening of titles/abstracts and removal of duplicates was performed and the full texts of the remaining potentially relevant articles were retrieved and reviewed.
UNASSIGNED: Thyroid and parathyroid scintigraphy remains integral in patients with thyrotoxicosis, thyroid nodules, differentiated thyroid cancer and, respectively, hyperparathyroidism. In the last years positron-emission tomography with different tracers emerged as a more accurate alternative in evaluating indeterminate thyroid nodules [18F-fluorodeoxyglucose (FDG)], differentiated thyroid cancer [124I-iodide, 18F-tetrafluoroborate, 18F-FDG] and hyperparathyroidism [18F-fluorocholine]. Other PET tracers are useful in evaluating relapsing/advanced forms of medullary thyroid cancer (18F-FDOPA) and selecting patients with advanced follicular and medullary thyroid cancers for theranostic treatments (68Ga/177Ga-somatostatin analogues).

OBJECTIVE: To investigate the clinical character of differentiated thyroid cancer (DTC) coexisting with Hashimoto\'s thyroiditis (HT) and provide state-of-art evidence for personalized radioactive iodine-131 therapy (RAIT) for patients coexisting with HT.
METHODS: From January 2000 to January 2023, PubMed, Embase, and Web of Science databases were searched for relevant original articles that published in English on the RAIT efficacy for DTC with HT. RevMan 5.4 and Stata 17.0 were used for data analysis.
RESULTS: Eleven studies involving 16 605 DTC patients (3321 with HT) were included. HT was more frequent in female (OR: 2.90, 95% confidence interval [CI]: 1.77-4.76, P < .00001). The size of tumour (MD: -0.20, 95% CI: -0.30 to -0.11), extrathyroidal extension rate (OR: 0.77, 95% CI: 0.67-0.90), and metastasis rate (OR: 0.18, 95% CI: 0.08-0.41) were less in HT, but tumour, node, metastasis (TNM) stage had no significant difference among HT and non-HT group. Disease-free survival (DFS) rate (OR: 1.96, 95% CI: 1.57-2.44, P < .00001), 5-year DFS (OR: 1.73, 95% CI: 1.04-2.89, P = .04), and 10-year DFS (OR: 1.56, 95% CI: 1.17-2.09, P = .003) were higher in HT group. The recurrent (OR: 0.62, 95% CI: 0.45-0.83, P = .002), RAIT dosage (MD = -38.71, 95% CI: -60.86 to -16.56, P = .0006), and treatment (MD: -0.13, 95% CI: -0.22 to -0.03, P = .008) were less in HT group.
CONCLUSIONS: DTC coexisting with HT was associated with less invasion. DFS of HT group was higher than non-HT group after RAIT. Low-dose treatment did not impair the efficacy of RAIT in DTC with HT.
CONCLUSIONS: Hashimoto\'s thyroiditis is a risk for DTC, but it minimalizes the progression of cancer and enhance the efficacy of RAIT, which should be considered in personalizing RAIT.

Thyroglobulin (Tg) is an iodinated glycoprotein, which is normally stored in the follicular colloid of the thyroid, being a substrate for thyroid hormone production. Since it is produced by well-differentiated thyroid cells, it is considered a reliable tumor marker for patients with differentiated thyroid carcinoma (DTC) during their follow-up after total thyroidectomy and radioiodine ablation. It is used to monitor residual disease and to detect recurrent disease. After total thyroid ablation, unstimulated highly sensitive Tg measurements are sufficiently accurate to avoid exogenous or endogenous thyrotropin (TSH) stimulation and provide accurate diagnostic and prognostic information in the great majority of DTC patients. Adopting sophisticated statistical analysis, i.e., decision tree models, the use of Tg before radioiodine theranostic administration was demonstrated to be useful in refining conventional, pathology-based risk stratification and providing personalized adjuvant or therapeutic radioiodine administrations. The follow-up of DTC patients aims to promptly identify patients with residual or recurrent disease following primary treatment. Our review paper covers the diagnostic, theranostic and prognostic value of thyroglobulin in DTC patients.

OBJECTIVE: Although I-131 is relatively safe, there is limited focus on probable eye-related side effects after radioactive iodine (RAI) therapy. Thus, we aimed to provide evidence for the adverse outcomes of I-131, exclusively in patients with thyroid cancer.
METHODS: A systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was designed to examine the ocular complications of RAI therapy. Databases including PubMed, Scopus, and Web of Science were searched until October 2023 with specific thyroid neoplasms, ophthalmology and iodine terms. After thorough screening and review, relevant data were extracted.
RESULTS: The database search yielded 3434 articles, which resulted in the final 28 eligible studies. These studies investigated ophthalmic symptoms following RAI therapy, classifying them as obstructive diseases (for example, nasolacrimal duct obstruction; median incidence rate: 6.8%), inflammatory symptoms (median incidence rate: 13%), and cataracts (median incidence rate: 2.5 and 5%). The most common time interval between RAI therapy and the onset of symptoms was within the first 12 months and then declined in the preceding years. A strong positive correlation was observed between higher I-131 doses of more than 100 to 150 mCi (3.7-5.55 GBq) and the risk of symptom development. Ages older than 45 also showed a significant association with nasolacrimal duct obstruction.
CONCLUSIONS: The risk of ophthalmic complications is associated with various factors, including the administration of high I-131 doses, age of more than 45 years, and time to event within the first 12 months. Considering these conditions may help enhance patient care and prevent adverse outcomes that may limit patients\' quality of life.

Radioiodine imaging in initial perioperative settings, after the total thyroidectomy, includes pre-treatment and post-treatment radioiodine imaging. While the benefit of post-treatment whole-body imaging (PT-WBI) is well established, the role of diagnostic whole-body imaging (dx WBI), prior to radioiodine (I-131) ablative or therapeutic doses, is controversial. Dx WBI has been abandoned in most nuclear medicine centers long ago. Planar low-dose dxWBI provides the volume of postoperative thyroid remnants, but it cannot detect occult metastatic foci in the neck. The modern integrated multimodality, i.e., SPECT/CT imaging, provides three dimensional images and accurate anatomic/metabolic data. This hybrid technology offers better spatial resolution but not better sensitivity. Dx WBI has low theranostic power because of the radioiodine indifference and low detection sensitivity for small-volume nodal disease in the neck. Since dx WBI cannot clarify the paratracheal cervical uptake, thyroid remnants may be easily misinterpreted as nodal disease, leading to a false N upstaging (from N0 stage to N1 stage) in DTC patients. Post-ablation I-131 imaging has a significant role in the initial staging of radioiodine-avid DTC and in the identification of non-radioiodine avid tumors. Additionally, SPECT/CT in the post-treatment setting provides more accurate initial TNM staging and better risk stratification of DTC patients. Post-treatment I-131 imaging is obligatory and must be performed in all DTC patients who receive radioiodine treatment.