[Guideline for Radioiodine Therapy for Benign Thyroid Diseases (6/2022 - AWMF No. 031-003)]

This version of the guideline for radioiodine therapy of benign thyroid disorders is an update of the version, which was published by the German Society of Nuclear Medicine (Deutsche Gesellschaft für Nuklearmedizin, DGN) in co-ordination with the German Society of Endocrinology (Deutsche Gesellschaft für Endokrinologie, DGE, Sektion Schilddrüse) and the German Society of General- and Visceral-Surgery (Deutsche Gesellschaft für Allgemein- und Viszeralchirurgie, DGAV) in 2015. This guideline was harmonized with the recommendations of the European Association of Nuclear Medicine (EANM). According to the German "Directive on Radiation Protection in Medicine" the physician specialised in nuclear medicine ("Fachkunde in der Therapie mit offenen radioaktiven Stoffen") is responsible for the justification to treat with radioiodine. Therefore, relevant medical indications for radioiodine therapy and alternative therapeutic options are discussed within the guideline. This procedure guideline is developed in the consensus of an expert group. This fulfils the level S1 (first step) within the German classification of Clinical Practice Guidelines.

The influence of thionamides on intra-thyroidal uptake of 131I during radioiodine-131 treatment of Graves' disease

Graves' disease is one of the most common causes of hyperthyroidism. Guideline recommendations advocate the intake of thionamides for at least 1 year. If hyperthyroidism persists, subsequent radioiodine-131 treatment (RIT) is a therapeutic option. Thionamides are known to influence intra-thyroidal bio-kinetics of iodine and should therefore be discontinued at least 3 days prior to RIT if possible. However, the required therapeutic activity has to be calculated individually by pre-therapeutic measurement of the uptake prior to RIT [radioiodine-131 uptake test (RIUT)] in Germany according to national guidelines. Therefore, the aim of this study was to quantify the influence of thionamides on intra-therapeutic uptake. A cohort of 829 patients with Graves' disease undergoing RIUT and RIT was analysed. Patients were subdivided into three groups. Group A: patients with carbimazole medication (n = 312), group B: patients with methimazole medication (n = 252) and group C: patients without thionamides (n = 265). Group A and B were further subdivided depending on the reduction of dosage of thionamides. In order to analyse the influence of thionamides, the variance of the determined individual extrapolated maximum intra-thyroidal uptake (EMU) between RIUT and RIT within the single groups and within the subgroups was statistically evaluated. When administering an equal dose of thionamides or no thionamides in RIUT and RIT (groups A1, B1 and C) no significant differences were detected when comparing EMU in RIT to EMU in RIUT (p > 0.05). In the subgroups A2-A4 (reduced dosage of carbimazole prior to RIT) EMU was significantly increased in RIT compared to RIUT [21% for a reduction of 0 to < 10 mg/d (A2), 39% for a reduction of 10-15 mg/d (A3) and 80% for a reduction of > 15 mg/d (A4)]. In the subgroups B2-B4 (reduced dosage of methimazole prior to RIT) EMU was as well significantly increased in RIT compared to RIUT [26% for a reduction of 0 to < 10 mg/d (B2), 36% for a reduction of 10-15 mg/d (B3) and 59% for a reduction of > 15 mg/d (B4)]. A significant dose-dependent increase of EMU in RIT compared to EMU in RIUT in patients discontinuing or reducing thionamides was detected. Therefore, thionamides should be discontinued at least 2 days prior to RIUT in order to achieve the designated target dose more precisely and to minimize radiation exposure of organs at risk.

The EANM guideline on radioiodine therapy of benign thyroid disease

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed.

The Side Effects of Therapeutic Radioiodine-131 on the Structure of Enamel and Dentin in Permanent Human Teeth

Simple Summary

Our research suggest radioiodine-131 used for differentiated thyroid carcinomas has an impact on the oral health of patients. We found that alteration of dental hard tissues starts after 6 h post-radioiodine administration. These findings highlight the importance of the multidisciplinary team management in the quality of life of the oncological patient.

Abstract

Radioiodine-131 (I-131) is an essential therapy for patients with differentiated thyroid carcinomas (DTC). Generally, I-131 is safe and well tolerated, but patients may present early or late complications in the oral and maxillofacial areas. Thus, the aim of this study was to evaluate in-vitro, the alteration of enamel and dentin after I-131 exposure using histopathological assessment, scanning electron microscopy (SEM) and atomic force microscopy (AFM). For I-131 irradiation, an in-vitro protocol was used that simulates the procedure for irradiation therapy performed for patients with DTCs. A total of 42 teeth were divided into seven groups (n = 6) and irradiated as follows: control, irradiation groups (3, 6, 12, 36, 48 h, 8 days). Histological changes were observed at 48 h (enamel surface with multifocal and irregular areas) and at 8 days (enamel surface with multiple, very deep, delimited cavities). SEM imaging revealed the enamel destruction progresses along with the treatment time increasing. The alterations are extended into the enamel depth and the dislocated hydroxyapatite debris is overwhelming. The enamel-dentine interface shows small gaps after 6 h and a very well developed valley after 12 h; the interface microstructure resulted after 8 days is deeply altered. The AFM imaging shows that I-131 affects the protein bond between hydroxyapatite nano-crystals causing loss of cohesion, which leads to significant increasing of nano-particles diameter after 6 h. In conclusion, both enamel and dentin appear to be altered between 12 and 48 h and after 8 days of treatment are extended in depth.

Radioiodine therapy of Graves' disease

Graves' disease (GD), the most common cause of hyperthyroidism, is an autoimmune disease directly caused by circulating autoantibodies that bind and activate the TSH receptor, inducing metabolic activation of the thyroid gland; this may be associated with important cardiac (atrial fibrillation) and ocular (ophthalmopathy) complications. Treating GD with real curative intent implies the full elimination of the functioning thyroid parenchyma using surgery or radioactive iodine therapy (RAI). RAI has been used in humans with hyperthyroidism since 1941, thanks to the pioneering work of a physician (Dr. Saul Hertz) and a physicist (Dr. Arthur Roberts). The rationale of RAI is based on the effect of radiation of ¹³¹I on target cells leading to DNA damage, both directly, through breakage of molecular bonds, and indirectly through the formation of free radicals. In particular, irradiation causes a broad spectrum of cellular damage due to the production of reactive oxygen species and lipid peroxidation of the plasma membrane. Thus, RAI-related cellular death takes place through both apoptosis and necrosis. The aim of this review was to summarize indications, efficacy, safety profile, and dosimetric aspects of RAI treatment in patients affected by GD.

[Thyroid medicine for ENT physicians]

Diseases of the thyroid gland are frequent incidental findings during ultrasound examination of the neck. They affect nearly one third of the normal population. Treatment is not always indicated; however, laboratory diagnostic measures must be initiated to specify the disease. The primary indications for consulting a thyroid specialist are thyroid nodules, goiters, autonomy of the thyroid gland, autoimmune diseases, Graves' disease, and Hashimoto thyroiditis. The aim of this review is to provide an overview of the most important thyroid diseases and their treatment options.

Sodium-iodide symporter positive cells after intracellular uptake of 99mTc versus α-emitter 211At

Purpose: We evaluated the DNA damaging potential of Auger electrons emitted in the decay of 99mTc compared to α-particles of 211At. Material and methods: The impact of 99mTc and 211At was monitored in a NIS-expressing rat thyroid cell model PC Cl3 with varying, yet defined intra- and extracellular radionuclide distribution (using ± perchlorate). The radiotoxicity of 99mTc and 211At was studied by the comet assay under neutral and alkaline conditions and colony formation. Results: In the presence of perchlorate, the radioactivity yielding 37 % cellular survival, A37, was estimated to be (0.27 ± 0.02) MBq/ml and (450 ± 30) MBq/ml for 211At and 99mTc, respectively. In absence of perchlorate, cellular radiotracer uptake was similar for both radionuclides (2.2 %, 2.7 %), yet the A37 was reduced by 82% for the α-emitter and by 95 % for 99mTc. Cellular dose increased by a factor of 5 (211At) and 38 (99mTc). Comet assays revealed an increased DNA damage after intracellular uptake of both radiotracers. Conclusions: The data indicate damage to the cell to occur from absorbed dose without recognizable contribution from intracellular heterogeneity of radionuclide distribution. Comet assay under alkaline and neutral conditions did not reveal any shift to more complex DNA damage after radionuclide uptake. Cellular uptake of 99mTc and 211At increased cellular dose and reduced clonogenic survival.

131I activity quantification of gamma camera planar images

A procedure to estimate the activity in target tissues in patients during the therapeutic administration of ¹³¹I radiopharmaceutical treatment for thyroid conditions (hyperthyroidism and differentiated thyroid cancer) using a gamma camera (GC) with a high energy (HE) collimator, is proposed. Planar images are acquired for lesions of different sizes r, and at different distances d, in two HE GC systems. Defining a region of interest (ROI) on the image of size r, total counts n _g are measured. Sensitivity S (cps MBq^-1) in each acquisition is estimated as the product of the geometric G and the intrinsic efficiency η ₀. The mean fluence of 364 keV photons arriving at the ROI per disintegration G, is calculated with the MCNPX code, simulating the entire GC and the HE collimator. Intrinsic efficiency η ₀ is estimated from a calibration measurement of a plane reference source of ¹³¹I in air. Values of G and S for two GC systems-Philips Skylight and Siemens e-cam-are calculated. The total range of possible sensitivity values in thyroidal imaging in the e-cam and skylight GC measure from 7 cps MBq^-1 to 35 cps MBq^-1, and from 6 cps MBq^-1 to 29 cps MBq^-1, respectively. These sensitivity values have been verified with the SIMIND code, with good agreement between them. The results have been validated with experimental measurements in air, and in a medium with scatter and attenuation. The counts in the ROI can be produced by direct, scatter and penetration photons. The fluence value for direct photons is constant for any r and d values, but scatter and penetration photons show different values related to specific r and d values, resulting in the large sensitivity differences found. The sensitivity in thyroidal GC planar imaging is strongly dependent on uptake size, and distance from the GC. An individual value for the acquisition sensitivity of each lesion can significantly alleviate the level of uncertainty in the measurement of thyroid uptake activity for each patient.

[Radioiodine therapy for benign thyroid diseases (version 5). German Guideline]

The version 5 of the guideline for radioiodine therapy of benign thyroid disorders is an update of the version 4, which was published by the German Society of Nuclear Medicine (Deutsche Gesellschaft für Nuklearmedizin, DGN) in co-ordination with the German Society of Endocrinology (Deutsche Gesellschaft für Endokrinologie, DGE, Sektion Schilddrüse) and the German Society of General- and Visceral-Surgery (Deutsche Gesellschaft für Allgemein- und Viszeralchirurgie, DGAV) in 2007. This guideline was harmonized with the recommendations of the European Association of Nuclear Medicine (EANM). According to the German "Directive on Radiation Protection in Medicine" the physician specialised in nuclear medicine ("Fachkunde in der Therapie mit offenen radioaktiven Stoffen") is responsible for the justfication to treat with radioiodine. Therefore, relevant medical indications for radioiodine therapy and alternative therapeutic options are discussed within the guideline. This procedure guideline is developed in the consensus of a representative expert group. This fulfils the level S1 (first step) within the German classification of Clinical Practice Guidelines.

Severe hyperthyroidism: aetiology, clinical features and treatment outcome

BACKGROUND

Severe hyperthyroidism (SH) is a serious medical disorder that can compromise life. There have not been systematic studies in which SH has been evaluated in detail. Here, our aims were: (1) to analyse both clinical and analytical features and outcome in patients with SH and (2) to compare these data with those found in more usual forms of hyperthyroidism. Patients and methods All patients diagnosed of SH (free thyroxine, FT4 > 100 pmol/l, NR: 11-23) seen in our endocrinology clinic in the last 15 years were studied and compared with a sample of patients with mild (mH; FT4, 23-50 pmol/l) and moderate (MH; FT4, 51-100 pmol/l) hyperthyroidism. Aetiology, clinical analytical and imaging data at diagnosis, therapeutic response and outcome were registered. Results A total of 107 patients with overt hyperthyroidism (81 females, mean age +/- SD 46.9 +/- 16.1 years) were evaluated. We studied a historic group with SH (n = 21; 14 females, 40.9 +/- 17.2 years) and, as a comparator group, we analyszed the data of 86 hyperthyroid patients (67 females, 48.4 +/- 15.5.6 years, NS) comparable in age and gender. The comparator group was classified in MH (n = 37, 26 females, 47.2 +/- 16.6 years) and mH (n = 49, 41 females, 49.4 +/- 14.8 years). In comparison with mH group, SH patients were significantly (P < 0.05) younger and showed a greater proportion of first episode of thyroid hyperfunction (P < 0.05). Graves' disease was the main aetiology in the three groups, but patients with SH showed the highest titre of TSH-receptor antibodies (TRAb) (P < 0.001). Heart rate and size of goitre were higher in SH group than in mH and MH groups (P < 0.01). Atrial fibrillation was more frequently reported in SH group than in MH and mH groups (15.8%vs. 5.4% and 0%, respectively, P < 0.05).

RESULTS

from logistic regression analysis showed that younger age [OR 0.958 (95% CI, 0.923-0.995), P = 0.026], presence of asthenia [OR 4.35 (1.48-12.78), P = 0.008] and higher heart rate [OR 1.03 (1.01-1.06), P = 0.013] were independent clinical variables associated to SH. SH patients showed similar biochemical parameters in comparison with mH group, except for increased serum aspartate aminotransferase (AST) (P < 0.01) and calcium (P < 0.05) levels, and decreased serum cholesterol (P < 0.05) and albumin (P < 0.05) concentrations. Logistic regression analysis showed that only AST [OR 1.07 (1.02-1.11), P = 0.005] was an independent biochemical variable associated to SH. No differences in the type of therapy, cure rate and time in achieving cure were found in SH subjects in relation to patients with milder forms of hyperthyroidism. FT4 was the only independent predictor of cure [OR 0.98 (CI 95%, 0.97-0.99), P < 0.05].

CONCLUSIONS

Graves' disease is the most common aetiology in patients with SH. This type of hyperthyroidism is usually de novo and is accompanied by more clinical signs, symptoms, and analytical derangements, as well as higher titres of TRAb at diagnosis than milder forms of hyperthyroidism. The present data are not able to show differences in treatment modality, time to achieve cure, and remission rate among patients with mild, moderate and severe hyperthyroidism.