Thyroid Radioactive Iodine Uptake Research Articles

Painless thyroiditis mimicking relapse of hyperthyroidism during or after potassium iodide or thionamide therapy for Graves' disease resulting in remission.

The diagnosis of painless thyroiditis (PT) during antithyroid drug (ATD) treatment of Graves' disease (GD) is difficult. We evaluated the thyroidal radioactive iodine uptake (RAIU) in 100 patients with relapsed thyrotoxicosis during or after careful ATD treatment. The RAIU was <5%/5 h in 35 patients (35%) (Group A - PT), 5%-15%/5 h in 6 patients (6%) (Group B - indefinite) and >15%/5 h in 59 patients (59%) (Group C - relapsed GD [rGD]). TSH receptor antibody (TBII) was positive in 4 (11.4%), 3 (50.0%) and 39 (only 66.1%) patients in Groups A, B and C, respectively. In Group A, the serum fT4 level spontaneously normalized after 35 (26-56) days, sometimes followed by transient hypothyroidism, confirming the diagnosis of PT. Nineteen (54.3%) had been treated with potassium iodide, and PT frequently occurred ironically when the ATD dosage was reduced. PT repeatedly occurred in nine patients. All went into remission smoothly or developed hypothyroidism, except one patient with strongly positive TBII who developed rGD after the resolution of PT (PT on GD). In 10 (50%) of 20 patients with negative TBII despite rGD in Group C, TBII became positive afterwards. In conclusion, it is important to recognize that PT can occur in the clinical course of GD, resulting in frequent remission despite relapse of PT. The thyroid function reflects the balance between the stimulating TBII activity and the responsiveness of the thyroid tissue (sometimes unresponsive and other times autostimulated). The RAIU is still a valuable tool in cases of ambiguous thyrotoxicosis.

PSAT335 Histopathological changes of the thyroid may be subtle yet important in Amiodarone induced thyrotoxicosis (AIT).

Abstract Background Amiodarone is an effective antiarrhythmic for several cardiac arrhythmias. Due to its high iodine content and long half-life with direct toxic effects on the thyroid gland, it is known to cause a spectrum of thyroid dysfunction. AIT type 1, a form of iodine-induced hyperthyroidism, and AIT type 2, a drug induced destructive thyroiditis, pose a diagnostic and therapeutic challenge. Since the physical and psychological consequences of long-term therapy with either condition are too large to ignore, it is crucial to differentiate between the two types. Histopathologic findings in AIT includes disrupted follicles filled with desquamated vacuolated epithelial cells, foamy macrophages, scattered lymphocytes, involution changes and fibrosis. However, these changes may be subtle in patients who have been treated with long term high dose steroids, but helpful in establishing either AIT 1 or 2. Case A 56-year-old man with a history of cardiomyopathy with an ejection fraction of 30% and atrial flutter treated previously with six months of amiodarone, presented for a routine appointment found to be in atrial flutter with rapid ventricular rate. The patient was off amiodarone therapy for ∼ 6 months prior to current presentation. The patient was referred to the ER where initial vital signs were remarkable for heart rate in the 140s. Exam was remarkable for mild tremor of the outstretched bilateral hands. Labs were remarkable for TSH of 0.01 ulU/ml (0.27-4.20), Free T4 of 2.2 ng/dl (0.93-1.70), Free T3 of 5.9 pg/ml(2.3-4.2). Thyroid ultrasonography revealed a heterogeneously enlarged thyroid gland with no increased vascularity, and 2.4 cm isthmus nodule of a TI-RAD-3. Thyroid stimulating immunoglobulins (TSI) of 96 (&amp;lt;140%), and thyroid peroxidase (TPO) of 2IU/ml (&amp;lt;9). Thyroid radioactive iodine uptake (RAIU) revealed a severely decreased uptake in the setting of amiodarone use. Mixed AIT was suspected and patient was placed on titrated dose of Methimazole (MMI) and Prednisone. Approximately three weeks later, patient was discharged on MMI 40 mg TID and Prednisone 60 mg daily. He had a close outpatient follow up with further titration of prednisone to 80 mg daily. Due to prolonged nature of disease, he was subsequently referred for total thyroidectomy. Histological examination revealed subtle changes including desquamated follicular epithelial cells and intrafollicular foamy macrophages. The thyroid architecture was maintained and no inflammatory infiltrates of fibrosis were noted. These findings are consistent with AIT type 2. Conclusion AIT is a challenging diagnosis, and in medically refractory cases, total thyroidectomy is a curative option. The pathological findings in a patients treated with prolonged steroids may dampen inflammation of AIT2, and therefore careful histologic examination and monitoring of inflammatory markers may help to consolidate diagnosis. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Predictive factors for the efficacy of 131I therapy with formulated dosage calculation on Graves' disease.

To analyse predictive factors to ensure the efficacy of iodine-131 (131I) therapy on Graves' disease (GD). Graves' disease patients from three tertiary medical centers were enrolled. Serological data, thyroid mass estimation, thyroid radioactive iodine uptake, thyroid texture and thyroid murmurs (bruits) were recorded. Iodine-131 treatment was performed by applying a formulated calculation method. After one year of follow-up, GD patients with euthyroidism and hypothyroidism were classified as the cured group, and the other thyroid function status refers to the uncured group. These analyses were performed by using SPSS17.0 software. A P value of less than 0.05 was considered statistically significant. A total of 970 GD patients, of which 540 patients (55.7%) belonged to the cured group, and 430 patients (44.3%) belonged to the uncured group, participated in the current analyses. Multivariate logistic regression analysis was performed. Moreover, estimated thyroid mass, thyroid murmurs (bruits), prescribed 131I dosage, FT3 and FT4 have independent prognostic value for 131I efficacy, and their odds ratios are 1.368, 2.283, 1.326, 1.467 and 1.419, respectively. Graves' disease patients who are undergoing 131I therapy using the formulated dosage calculation could be influenced by thyroid mass, thyroid murmurs, 131I dosage and thyroid function.

Factitious Hyperthyroidism - A Diagnostic Challenge: Case Report

Thyrotoxicosis factitia is not very uncommon but most often underestimated in the developing world. There are considerable chance of it being underdiagnosed or missed in our routine clinical practice which can have deleterious effects on patients and leads to significant patient morbidity apart from putting burden on health-care resources. It’s a condition which arises from the long term ingestion of thyroid hormones most often in those individuals who have psychological issues, for cosmetic reasons or accidental ingestion of high quantity of thyroid hormones, which has been especially seen in medical personnel who have easy access to thyroid hormones. Most of the times the patients deny the fact that they are taking thyroid hormones despite being aware of it. Hereby our team report a case of thyrotoxicosis factitia masquerading as refractory thyrotoxicosis in a young female patient diagnosed to have uncontrolled hyperthyroidism for more than five years on high dose methimazole despite the fact that her thyroid radioactive iodine uptake repeated twice showed very low uptake and was in favor of thyroiditis. A high index of clinical suspicion led to a detailed history and review of her file which eventually led us to the diagnosis of factitial hyperthyroidism.

Clinical Profile of Patients with Hyperthyroidism in Zagazig University Hospitals

Hyperthyroidism is a condition that occurs due to over production of thyroid hormones by the thyroid gland . It can be categorized according to thyroid hormone levels into overt and subclinical hyperthyroidism. Also could be classified into, normal (or high) and low thyroid radioactive iodine uptake according to radioiodine uptake. So, the aim of this study was to evaluate the difference in the clinical profile between hyperthyroid patients and its relation to thyroid scan imaging. Also to avoid prescribing antithyroid medications to patients with thyroiditis, this could lead to hypothyroidism . Materials and methods: This is a prospective cohort study for patients with hyperthyroidism. Patients have been enrolled from Endocrinology Outpatient Clinic at Zagazig University Hospitals in the period from December 2018 to October 2020. Results: patients were divided into two major groups, overt hyperthyroidism (group 1) and subclinical hyperthyroidism (group 2). All patients of group (1) had abnormal thyroid gland examination but, only 50 % of group (2) patients had showed abnormal gland examination (p= <0.001). 83 .3% of patients of group (1) had high thyroid uptake and 62.5 % of patients of group (2) had high thyroid uptake (p=0.108). There was highly statistical significance between the two groups as regard F. T4( P = <0.001) and F .T3 (p = < 0.001 ) , but no difference in TSH( p =0.223) . Conclusion: The thyroid scan had cross linkage with abnormal thyroid function ,

The effect of per os vs subcutaneous 123 iodine administration on percentage thyroidal radioactive iodine uptake in normal cats.

BackgroundHistorical and recent literature disagree on whether a higher PO 131I dosage, compared to IV or SC routes, is required for successful resolution of spontaneous hyperthyroidism in cats, necessitating investigation into the effect of PO and injectable radioactive iodine administration on % thyroidal radioactive iodine uptake (RAIU).Hypothesis/ObjectivesTo investigate the effect of PO and SC routes of 123I administration on paired % thyroidal RAIU in euthyroid cats. Specifically, a 1.5‐fold difference (50% relative change) was hypothesized, which in absolute terms can be expressed as a 3.25% increase in the mean %RAIU of 7.04% after PO 123I administration to 10.56% after SC dosing.AnimalsSeven healthy euthyroid teaching‐research colony cats.MethodsA randomized, radiologist‐blinded crossover study comparing %RAIU after PO and SC 123I administration.ResultsPercentage thyroidal RAIU values (mean ± SD; 95% confidence interval) after PO (4.81% ± 1.63%; 3.30%‐6.23%) and SC (5.26% ± 2.43%; 3.01%‐7.51%) 123I administration were associated with a median within‐pair absolute difference of 0.2% (range: min, 0.1%‐max, 4.9%). Statistical significance was not achieved (P = .45). Six of 7 cats had a within‐pair absolute difference of 0.1% to 0.9% (relative change of 4%‐20%), but a single outlier cat had a within‐pair absolute difference of 4.9% (relative change of 108%).Conclusions and Clinical ImportanceThis study did not detect an effect of 123I administration route on paired % thyroidal RAIU in euthyroid cats. However, a type 2 statistical error due to small sample size is possible.

Identification of Two Different Phenotypes of Patients with Amiodarone-Induced Thyrotoxicosis and Positive Thyrotropin Receptor Antibody Tests.

Introduction: Serum thyrotropin (TSH) receptor antibodies (TRAbs) are occasionally found in patients with amiodarone-induced thyrotoxicosis (AIT), and usually point to a diagnosis of type 1 AIT (AIT1) due to Graves' disease (GD). However, the TRAb role and function in AIT have not been clarified. Methods: A retrospective cohort study of 309 AIT patients followed at a single academic center over a 30-year period. AIT TRAb-positive patients (n = 21, 7% of all cases) constituted the study group; control groups consisted of type 2 AIT (AIT2) TRAb-negative patients (n = 233), and 100 non-AIT patients with GD. Clinical and biochemical data at diagnosis and during the course of disease were compared. Histological samples of patients who had total thyroidectomy were reviewed. Stored serum samples were used for a functional assay of TRAb class G immunoglobulins (IgGs) in Chinese hamster ovary (CHO) cells stably transfected with complementary DNA encoding for the TSH receptor. Results: TRAb-positive patients were grouped according to color flow Doppler sonography, radioactive iodine thyroid uptake, and duration of amiodarone therapy before thyrotoxicosis in type 1 (n = 9, 43%; TRAb1) or type 2 (n = 12, 57%; TRAb2) AIT. TRAb1 patients had clinical and biochemical features indistinguishable from GD controls, and were responsive to methimazole. Conversely, TRAb2 patients had clinical features similar to AIT2 controls, and were responsive to glucocorticoids, but not to methimazole. The CHO cell functional assay demonstrated that TRAb1 IgGs had a stimulatory effect on cyclic AMP production, which was absent in TRAb2 IgGs. Pathology in TRAb1 showed hyperplastic thyroid follicles and mild lymphocyte infiltration, reflecting thyroid stimulation. On the contrary, TRAb2 samples revealed follicle destruction, macrophage infiltration, and sometimes fibrosis, consistent with a destructive process. Conclusions: Almost 60% of TRAb-positive AIT patients had a destructive thyroiditis. TRAb-positive tests in AIT patients do thus not necessarily imply a diagnosis of GD and AIT1, and should be evaluated in the clinical and biochemical setting of each AIT patient and confirmed by measuring thyroid-stimulating immunoglobulins.

Evaluation on the Diagnostic Value of Nuclear Medicine and Ultrasound Examination in Subacute Thyroiditis

This study was to investigate and analyze the diagnostic value of nuclear medicine and ultrasound examination in subacute thyroiditis. Three hundred cases with subacute thyroiditis were selected as the research group, while another 300 cases with health examination were enrolled as the control group, both ranging from August 2013 to October 2016. Patients in the research group underwent the detection with erythrocyte sedimentation rate, serum free triiodothyronine, serum free thyroxine, high sensitive thyroid stimulating hormone, thyroid radioactive iodine uptake in 6 h and radionuclide thyroid scan. Patients in both research group and control group took the ultrasound examination. The results of ultrasound examination showed that the thyroid width and thickness in the research group were both significantly larger than those in the control group, revealing statistical significances (p<0.05). The positive rate by nuclear medicine was significantly higher than that by ultrasound examination, revealing p<0.05. Diagnostic positive rate with the combination of nuclear medicine and ultrasound examination was much ideal, that was 100 %. Nuclear medicine and ultrasound examination in subacute thyroiditis could achieve good diagnostic results and provide the accuracy rate of the diagnosis, thus further providing valuable basis for clinical treatment.

Efficacy and safety of Xiaochaihu decoction for subacute thyroiditis: A protocol of systematic review and meta-analysis.

Background:Subacute thyroiditis (SAT) is a transient and self-limiting inflammatory thyroid disease. There is no clear evidence for specific etiology, but it is generally thought to occur after viral infection. Characteristics of SAT include severe pain of the anterior neck, enlarged firm thyroid, disordered thyroid function, elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), typical ultrasound findings (hypoechoic areas) and low thyroid uptake of radioactive iodine or technetium-99 m because of the destructive etiology of the hyperthyroidism. Evidences showed Xiaochaihu decoction (XCHD) has a significant effect on improving the symptoms of SAT patients. The purpose of this study is to assess the safety and effectiveness of XCHD for patients with SAT.Methods and analysis:The literature that has been identified via searching 6 Chinese electronic databases and eight English electronic databases from inception to September 21, 2020 will be included in the study. Research selection, data extraction as well as research quality assessment will be completed by 2 experienced researchers independently. The primary outcome is remission rate. Data analysis will be conducted by the RevMan 5 software, and GRADE will help to assess the level of evidence. The heterogeneity of data will be investigated by a heterogeneity x2 test, as well as the Higgins I2 test. A subgroup analyses and sensitivity analysis will be conducted to explore the sources of heterogeneity.Results:The results of this study will be published in a peer-reviewed journal.Conclusion:This study will draw a conclusion about whether XCHD is safe and effective in treating SAT on the basis of evidence-based medicine. This conclusion will provide areliable scientific evidence for the alternative treatment for the management of SAT.OSF registration number:https://osf.io/8hbue.

Automated MicroSPECT/MicroCT Image Analysis of the Mouse Thyroid Gland.

The ability of thyroid follicular cells to take up iodine enables the use of radioactive iodine (RAI) for imaging and targeted killing of RAI-avid thyroid cancer following thyroidectomy. To facilitate identifying novel strategies to improve 131I therapeutic efficacy for patients with RAI refractory disease, it is desired to optimize image acquisition and analysis for preclinical mouse models of thyroid cancer. A customized mouse cradle was designed and used for microSPECT/CT image acquisition at 1 hour (t1) and 24 hours (t24) post injection of 123I, which mainly reflect RAI influx/efflux equilibrium and RAI retention in the thyroid, respectively. FVB/N mice with normal thyroid glands and TgBRAFV600E mice with thyroid tumors were imaged. In-house CTViewer software was developed to streamline image analysis with new capabilities, along with display of 3D voxel-based 123I gamma photon intensity in MATLAB. The customized mouse cradle facilitates consistent tissue configuration among image acquisitions such that rigid body registration can be applied to align serial images of the same mouse via the in-house CTViewer software. CTViewer is designed specifically to streamline SPECT/CT image analysis with functions tailored to quantify thyroid radioiodine uptake. Automatic segmentation of thyroid volumes of interest (VOI) from adjacent salivary glands in t1 images is enabled by superimposing the thyroid VOI from the t24 image onto the corresponding aligned t1 image. The extent of heterogeneity in 123I accumulation within thyroid VOIs can be visualized by 3D display of voxel-based 123I gamma photon intensity. MicroSPECT/CT image acquisition and analysis for thyroidal RAI uptake is greatly improved by the cradle and the CTViewer software, respectively. Furthermore, the approach of superimposing thyroid VOIs from t24 images to select thyroid VOIs on corresponding aligned t1 images can be applied to studies in which the target tissue has differential radiotracer retention from surrounding tissues.

Influence of iodine supply on the radiation-induced DNA-fragmentation

The protective effect of stable iodide against radiation on thyroid cells was investigated. One physiological effect of stable iodine is well-rooted: stable iodine leads to a reduced thyroid uptake of radioactive iodine. This work wants to focus on an intrinsic effect of stable iodine by which DNA-damage in cells is prevented.To investigate this intrinsic effect thyroid cells (FRTL-5) were externally irradiated by use of a linear accelerator (LINAC) applying energy doses of 0.01 Gy–400 Gy and by incubation with various activity concentrations of 131I (0.1–50 MBq/ml for 24 h). We added stable iodine (NaI) to the cells prior to external irradiation and investigated the effect of the concentration of stable iodine (1, 5, 15 μg/ml). In order to clarify whether thyroid cells have a distinctive and iodine-dependent reaction to ionizing radiation, keratinocytes (HaCaT) without NIS were exposed in the same way. As indicators for the cellular reaction, the extent of DNA fragmentation was determined (Roche, Mannheim, Germany).Both cell types showed distinct ability for apoptosis as proven with camptothecin. The addition of “cold” iodine from 1 to 15 μg/ml without irradiation (“negative control”) did not change the response in both cell types. Plausibly, the radio-sensitivity of both cell types did increase markedly with increasing radiation dose but the radiation effect is diminished if iodine is added to the thyroid cells beforehand. The DNA-damage in thyroid cells after addition of cold iodine is reduced by a factor of 2–3. The skin cells did not show an significant change of radio-sensitivity depending on the presence of cold iodine. Elementary iodine possibly acts as a radical scavenger and thus markedly reduces the secondary radiation damage caused by the formation of cytotoxic radicals. This intrinsic radioprotective effect of iodine is seen only in cells with NIS.

Derivation of the critical effect size/benchmark response for the dose-response analysis of the uptake of radioactive iodine in the human thyroid.

Potential adverse effects of chemical substances on thyroid function are usually examined by measuring serum levels of thyroid-related hormones. Instead, recent risk assessments for thyroid-active chemicals have focussed on iodine uptake inhibition, an upstream event that by itself is not necessarily adverse. Establishing the extent of uptake inhibition that can be considered de minimis, the chosen benchmark response (BMR), is therefore critical. The BMR values selected by two international advisory bodies were 5% and 50%, a difference that had correspondingly large impacts on the estimated risks and health-based guidance values that were established. Potential treatment-related inhibition of thyroidal iodine uptake is usually determined by comparing thyroidal uptake of radioactive iodine (RAIU) during treatment with a single pre-treatment RAIU value. In the present study it is demonstrated that the physiological intra-individual variation in iodine uptake is much larger than 5%. Consequently, in-treatment RAIU values, expressed as a percentage of the pre-treatment value, have an inherent variation, that needs to be considered when conducting dose-response analyses. Based on statistical and biological considerations, a BMR of 20% is proposed for benchmark dose analysis of human thyroidal iodine uptake data, to take the inherent variation in relative RAIU data into account. Implications for the tolerated daily intakes for perchlorate and chlorate, recently established by the European Food Safety Authority (EFSA), are discussed.

Single, very low dose (0.03 mg) of recombinant human thyrotropin (rhTSH) effectively increases radioiodine uptake in the I-131 treatment of large nontoxic multinodular goiter.

Radioiodine therapy (RIT) in patients with large nontoxic multinodular goiter (MNG) recently becomes more common method in comparison to surgery (especially in elderly patients and with contraindications because of severe chronic diseases other systems). Repeatedly low thyroid radioactive iodine uptake (RAIU) decreases effectiveness of RIT or makes it impossible. The recombinant human thyrotropin can increase RAIU and improve the results of RIT. was to assess the influence of a single very low dose (0.03 mg) of rhTSH on RAIU and thyroid function in euthyroid (MNG-EU) and subclinical hyperthyroid (MNG-SC) patients with a large multinodular goiter. 40 patients (14 male, 26 female, age 57-80 yr) with large non-toxic MNG over 80 grams and with baseline RAIU < 40% were included into the double-blind randomized study and divided into two groups: rhTSH-group and control group. First group received the single intramuscular injection of 0.03 mg rhTSH and the second received placebo. The RAIU were measured 24 and 48 hours after the rhTSH and then all the patients were administered therapeutic doses of I-131. TSH and free thyroxine levels were measured at 1st and 2nd day after the injection of rhTSH and later, at 4 and 8 weeks after the RIT. The mean RAIU increased significantly from 30.44 ± 7.4% to 77.22 ± 8.7% (p < 0.001). There were no statistically significant differences in RAIU between euthyroid (MNG-EU) and subclinically hyperthyroid (MNG-SC) patients. The peak of serum TSH was noticed 24 hours after rhTSH injection and in MNG-EU patients it has remained within normal range, similarly as fT4. In the MNG-SC group the administration of rhTSH resulted in a significant increase in the TSH values after 24 hours, whose mean level slightly exceeded the upper limit of the normal range with normalization at 48 hours. 8 weeks after the RIT, the TSH and fT4 levels did not exceed the normal range and did not differ in a statistically significant way. Even the single very low dose of rhTSH increases the values of RAIU in significant way, in euthyroid and subclinically hyperthyroid patients. The administration of rhTSH is well-tolerated. Neoadjuvant administration of a low dose (0.03 mg) of rhTSH before I-131 seems to be an optimal method of management which may increase the effectiveness of RIT and decrease the exposure of the patients to absorbed doses of ionizing radiation.

Differentiation between Graves' disease and painless thyroiditis by diffusion-weighted imaging, thyroid iodine uptake, thyroid scintigraphy and serum parameters.

The aim of the present study was to assess the apparent diffusion coefficient (ADC) in diffusion-weighted imaging (DWI), thyroid radioactive iodine uptake (RAIU), thyroid scintigraphy and thyrotropin receptor antibody (TRAb) levels in the differential diagnosis between Graves' disease (GD) and painless thyroiditis (PT). A total of 102 patients with GD and 37 patients with PT were enrolled in the study. DWI was obtained with a 3.0-T magnetic resonance scanner, and ADC values were calculated. RAIU and thyroid scintigraphy were performed. Tissue samples were obtained from patients with GD (6 cases) following thyroidectomy, and from patients with PT (2 cases) following biopsy. Receiver operating characteristic (ROC) curves were drawn, optimal cut-off values were selected, and the sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were assessed. It was found that the ADC, TRAb and RAIU were significantly higher in GD than in PT (P<0.05). ROC curves showed areas under the curves for RAIU, ADC and TRAb that were >0.900. RAIU was the reference method. Sensitivity, specificity, accuracy, PPV and NPV were 96.078, 91.892, 95.000, 97.059 and 89.474% for ADC, and 88.235, 75.676, 84.892, 90.909 and 70.000% for TRAb, after the optimal thresholds of 1.837×10-3 mm2/sec and 1.350 IU/ml were determined respectively. Histopathology showed that tissue cellularity in PT was much higher than in GD due to massive lymphocytic infiltration. The results of the present study indicate that RAIU, ADC and TRAb are of diagnostic value for differentiating between GD and PT. DWI has great potential for thyroid pathophysiological imaging because it reflects differences in tissue cellularity between GD and PT.

Influence of (99m)Tc-pertechnetate thyroid imaging on radioactive iodine uptake.

To observe the influence of (99m)Tc-pertechnetate on radioactive iodine uptake (RAIU) in patients with Graves' disease (GD) hyperthyroidism after thyroid scintigraphy. Totally 40 patients in whom thyrotoxicosis was diagnosed at Peking Union Medical College Hospital from 2013 March to May were recruited, and RAIU were performed in all patients. Gamma-count rates at 1 h,25 h,49 h,73 h and 169 h were examined respectively after intravenous injection of 185 MBq (5mCi)of (99m)Tc-pertechnetate. The counts of (99m)Tc and (131)I as well as effective half-life of (99m)Tc (Teff (99m)Tc) were calculated respectively according to the half-life formula. The ratio of (99m)Tc to background counts (1200) was calculated as a reference value to evaluate biokinetics of (99m)Tc.The relationship between the effective half-life of (99m)Tc(Teff (99m)Tc) and the level of free triiodothyronine (FT3), free thyroxine (FT4), and effective half-life of (131)I (Teff (131)I)were also evaluated. After intravenous injection of (99m)Tc-pertechnetate, (99m)Tc counts at 1h, 25h, 49h, 73h and 169h was (440.16±247.35)×10(4), (11.37±10.67)×10(4), (0.13±0.36)×10(4), (-0.1±0.19)×10(4), respectively, and the ratio of (99m)Tc to background at 1h, 25 h, and 49 h was 3668, 94.75, and 1.08, respectively. The Teff (99m)Tc was (4.41±0.49)h. Inverse correlations were noted between the effective half-life of Teff (131)I and level of FT3 (r=-0.503, P=0.003) and FT4 (r=-0.516, P=0.002), while no significant correlation was found between the Teff (99m)Tc and FT3, FT4 as well as the Teff (131)I. Teff (99m)Tc is 4.41h, (99m)Tc-pertechnetate thyroid imaging does not influence RAIU three days after injection of (99m)Tc-pertechnetate. Teff (99m)Tc shows no correlation with the thyroid hormone level and RAIU of Graves's hyperthyroidism.

May dental extraction trigger subacute thyroiditis?

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Two Cases-Report of Mild Graves?Disease Following Subacute Thyroiditis: More Evidence of the Role of Thyroglobulin in The Pathogenesis of Autoimmune Thyroid Disease?

Two middle aged Caucasian women with no previous history of thyroid or any other disease developed typical subacute thyroiditis (SAT) with minimal thyroidal radioactive iodine uptake. A few months after restoration of euthyroidism and discontinuation of corticosteroid therapy, they developed mild hyperthyroidism due to Graves’ disease (GD), as judged by the increased diffuse thyroidal radioactive iodine uptake. Both of them were genetically predisposed to the above diseases since they had the certain HLA haplotypes for SAT and GD. Also they developed anti- thyroglobulin antibodies during the period of GD. We hypothesize that genetic background and the increased load of Tg or other autoantigens released from the distracted damaged thyroid gland due to SAT triggered the development of GD a few months later.

A dual hyperthyroidism

In December, 2008, an 18-year-old woman, presented with weight loss, palpitations, dyspnoea, heat sensitivity, and excessive sweating. On examination, her pulse rate was 140 bpm and regular, and her blood pressure 130/60 mm Hg. Her weight was 48 kg and height 158 cm. She was anxious and hyperkinetic, with a thyroid stare and lid lag. She had a fi ne tremor of her hands. Her thyroid was diff usely enlarged (WHO goitre grading 2–3) and had an audible bruit. Thyroid hormone concentrations were high (free tri-iodothyronine 16·0 pmol/L, normal 3·1–7·4; free thyroxine 59·2 pmol/L, normal 10·3–21·9) and thyrotropin was suppressed (0·003 mIU/L, normal 0·45–4·5). Test for thyroid receptor antibody was strongly positive at 34 U/L (normal <1). A technetium scan revealed diff use thyromegaly with homogeneously intense uptake. 24 h thyroidal radioactive iodine uptake was 78%, and a diagnosis of Graves’ hyperthyroidism was made. Methimazole (10 mg three times daily) and propranolol (20 mg three times daily), were prescribed. After ten weeks, treatment with 16 mCi of radioactive iodine-131 was undertaken. Unexpectedly, 6 months later, a 3 cm fi rm nodule was palpable in the region of thyroid right lobe; the left lobe was barely palpable. Thyroid hormone concentrations were still high (free tri-iodothryronine 7·6 pmol/L; free thyroxine 21·9 pmol/L) and thyrotropin was low (0·02 mIU/L). Sonography showed a slightly enlarged thyroid with a solitary nodule in the right lobe. Scintigraphy showed that the nodule was hyperfunctioning (hot node) with no isotope uptake in the rest of

Endogenous Thyroid-Stimulating Hormone and Radioactive Iodine Uptake in Normal Subjects

In 105 normal volunteers, 52 male and 53 female, mean age 45 (range, 20-68), serum thyroid-stimulating hormone (TSH) (1.46 ± 0.7; range, 0.43-3.87 microUI/mL) and 24-hour thyroid radioactive iodine uptake (RAIU) (16.15% ± 4.78% range, 6.45%-30.08%) were measured. Additionally, TSH was 1.18 ± 0.5 microUI/mL for 20 to 29 year-olds and 1.59 ± 0.9 microUI/mL for 60 to 68 year old (P = 0.037). RAIU was 18.30 ± 4.5 for 20 to 29-year-olds and 14.92 ± 3.1 for 60 to 68 year-olds (P = 0.009). TSH trends positively and RAIU at 24 hours correlates negatively with aging of the pituitary axis.

Thyroid status of female rhesus monkeys and preliminary information on impact of perchlorate administration

Thyroid status was assessed in adult female rhesus monkey breeders at the California National Primate Research Center at the beginning of the breeding season. The 95% confidence intervals for thyrotropin (TSH), thyroxine (T(4)) and triiodothyronine (T(3)) (n = 66-80) were similar to those previously reported in smaller samples of macaque monkeys. Based on human criteria, 10 of 80 monkeys (12%) were hypothyroid (TSH > 2.0 µIU/mL). Because hypothyroxinaemia can be a risk factor in pregnancy, T(4) status was compared with past breeding history, breeding outcome for that season and general health records in a subset of 42 breeders. Age, weight and parity did not differ between monkeys in the lowest T(4) quartile as compared with those in the upper three quartiles. However, T(4) concentrations were significantly associated with the number of missed menstrual cycles during the previous breeding season. In additional work, three healthy lactating rhesus monkeys were given three different doses of environmental contaminant and thyroid iodine uptake inhibitor, ammonium perchlorate (0.006, 0.34, 12.8 mg/kg/day, respectively) in food for two weeks. Thyroid status variables (TSH, T(4), T(3), thyroid radioactive iodine uptake) were then measured. In the monkey receiving the highest perchlorate dose, iodine uptake was suppressed relative to baseline. The study shows the availability of tools to study thyroid status in rhesus monkeys, the variability of thyroid status in the breeder colony and the potential ability of environmental factors to influence thyroid status.