Course Of Subacute Thyroiditis Research Articles

The course of subacute thyroiditis from COVID-19 infection

The aim of this literature review is the analysis of the new data on subacute thyroiditis that emerged due to studying of potential effect SARS-CoV-2 has on disease’s manifestation and clinical course. The pandemic affected hundreds of millions of people, and thyroiditis as a consequence of viral infection has become more frequently observed in scientific research and case reports. Many academic works indicate that the virus directly impacts both the thyroid gland and the immune system, and some new pathogenic mechanisms were discovered during the course of the pandemic. Despite the fact that subacute thyroiditis is a self-limiting disease, its possible outcome is a permanent primary hypothyroidism with a need of a lifelong thyroid hormone replacement therapy. It also has a tendency to be relapsing. Certain characteristics has been found which show how modern de Quervain thyroiditis is different from the one several years ago. The scale of the pandemic made it evident for scientific community that there is a need for a rapid design of a vaccine as a specific preventive measure. Millions of people received COVID-19 vaccines and reports about subacute thyroiditis following the vaccination started to emerge, the systemic reviews on the issue were written, all this is also highlighted in this review article. Despite the fact that the World Health Organization declared an end to the pandemic in May 2023, the virus itself is likely to still be circulating in the population and it will continue to be one of the etiological factors behind de Quervain thyroiditis, also, coronaviral evolution did not come to an end.

FRI461 Two-years Course Of Subacute Thyroiditis After COVID-19 Vaccination: A Case Report

Abstract Disclosure: S. Yoshida: None. COVID-19 has been reported to cause subacute thyroiditis. Furthermore, the literature includes cases of COVID-19 vaccine-related subacute thyroiditis, but few reports describe the long-term course of vaccine-induced subacute thyroiditis. Herein, we report the case of a 47-year-old woman with no medical history who developed subacute thyroiditis after mRNA COVID-19 vaccination and was followed up for 2 years. Her fever persisted after the second dose of the COVID-19 vaccine, and she became aware of left anterior neck pain 8 days later. There were no infectious disease symptoms or signs in the patient’s history or at a recent physical examination. All thyroid autoantibodies were negative. On ultrasound, the thyroid gland was diffusely enlarged, and internal echogenicity was diffusely hypoechoic, coarse, and color Doppler blood flow signals were decreased without confinement to the pain area. She was diagnosed with subacute thyroiditis with tender thyroid swelling, thyrotoxicosis, and an inflammatory reaction. It was suspected that there was a causal link between the onset of subacute thyroiditis and COVID-19 mRNA vaccination because it developed immediately after vaccination and there were no other obvious causes. She was started on prednisolone, and her symptoms improved rapidly, leading to hypothyroidism 1 month later. The swelling of the thyroid gland improved rapidly, and it became atrophic several months after the onset of subacute thyroiditis. She never received any additional vaccinations. Two years after the onset, there was no recurrence of subacute thyroiditis, thyroid atrophy persisted, and the patient required levothyroxine supplementation (100 µg/day). Subacute thyroiditis generally has a good prognosis and rarely leads to permanent hypothyroidism. Subacute thyroiditis due to vaccination may follow a different course than that due to typical viral infection, and we need to examine its long-term prognosis. Presentation: Friday, June 16, 2023

FRI463 A Case Of Post COVID-19 Subacute Thyroiditis: A Thyroid Equivalent Of Long COVID?

Abstract Disclosure: N. Shiraliyeva: None. A. Rios Chen: None. E. Azimi-Nekoo: None. P. Kishore: None. Background: The thyroid can be affected by COVID-19 either directly through viral infection or indirectly through abnormal immune regulation (1). We report a case of subacute thyroiditis (SAT) induced by COVID-19 in which thyroid function (TFT) abnormalities lasted for over a year. Case Presentation: A 36 year old woman with a history of T2DM presented to the clinic with tachycardia, chills, tremors, and subjective fever. On exam, she had mild diffuse non-tender thyromegaly. History was significant for COVID-19 infection one month prior and she denied taking any supplement, including biotin. Laboratory data revealed TSH of 0.064 (0.270-4.2 uIU/mL), prior 0.3 in 2017, FT4 of 1.24 (0.75 – 2.0 ng/dL), TT3 129 (60 - 181.0 ng/dL ), negative TSI, TRAb, and TPO antibodies. Thyroid ultrasound demonstrated normal vascularity and no evidence of thyroid enlargement or nodules. Nuclear medicine uptake scan exhibited low thyroid uptake of 5.9 %. A diagnosis of COVID-19-related SAT (COVID-SAT) was made and she was treated with propranolol. She continued to have palpitations and TSH remained low for 15 months. TSH normalized at 17 months and repeat thyroid uptake scan demonstrated a normal uptake at 15.5%. Conclusion: SAT is a self-limited inflammatory thyroid disorder usually preceded by a viral upper respiratory tract infection. COVID-SAT has been described in multiple patients. Like typical SAT, COVID-SAT can present with neck pain, asthenia, fever and palpitations (1). COVID-19 infection can cause SAT either directly through ACE-2 mediated viral invasion of cells or indirectly through abnormal immune regulation leading to cytokine storm (1). Our literature search found 20 patients with COVID-SAT. The vast majority were middle-aged females with no history of thyroid issues. In most cases of COVID-SAT, TFT abnormalities lasted 4 to 8 weeks (1). Our patient is unique in that her TFT abnormalities lasted for over a year, which is different from the usual course of SAT or COVID-SAT. Prospective studies on patients with long COVID without associated thyroid disorders demonstrated that TFT and anti-thyroid antibodies did not play a significant role in long COVID (2). We speculate that the suppression of TSH and low thyroid uptake for >1 year, may represent a form of long COVID of the thyroid. More studies are needed to elucidate the mechanism of long term effects of COVID infection on the thyroid and thyroid function.

Impact of the COVID-19 pandemic on the incidence, seasonal distribution, and characteristics of subacute thyroiditis.

PurposeAn increasing number of cases of subacute thyroiditis (SAT) related to the coronavirus disease 2019 (COVID-19) and its vaccines continue to be published. The aim of this study was to investigate any change in the incidence and characteristics of SAT by comparing the pre-pandemic and pandemic periods.MethodsThis retrospective, single-center study included 432 newly-diagnosed SAT patients between January 2018 and December 2021. The annual frequency of SAT was calculated as the number of newly-diagnosed SAT cases divided by the total number of outpatients that year.ResultsThe frequencies of newly-diagnosed SAT were 0.136% in 2018, 0.127% in 2019, 0.157% in 2020, and 0.114% in 2021 (p = 0.19). While SAT patients were clustered in the autumn (35.1%) in 2018 and 2019, it was found that this cluster shifted to the winter (33.0%) in 2020 and 2021, in parallel with COVID-19 case peaks (p = 0.017). The patients were separated into two groups as pre-COVID-19 pandemic SAT (n = 272) and COVID-19 pandemic SAT (n = 160). The mean ages of the groups were similar. There were more male patients in the COVID-19 pandemic SAT group than in the pre-pandemic group (30.6% vs. 18.7%, p = 0.005). Frequencies of overt hyperthyroidism and median free-thyroxine levels were significantly higher in the COVID-19 pandemic SAT group (p = 0.029, p = 0.001). Treatment modalities, recurrence rates, and permanent hypothyroidism were similar in both groups.ConclusionWith the COVID-19 pandemic, although there was a change in seasonal variation of SAT and an increase in the number of male patients, there was no change in the incidence and clinical course of SAT.

Early Thyroid Volume Reduction in Subacute Thyroiditis Can be a Potential Indicator for Hypothyroidism.

BackgroundThyroid volume has been reported to decrease significantly after episodes of subacute thyroiditis (SAT); however, the relationship between thyroid volume and hypothyroidism remains unclear. This study assessed the association between thyroid volume changes and the hypothyroid phase in patients with SAT, a condition that can progress to persistent hypothyroidism.MethodsThis retrospective study evaluated 37 patients diagnosed with SAT at the Department of Endocrinology and Metabolism of Chonnam National University Hwasun Hospital (CNUHH) between 2016 and 2021. Since we could not determine the clinical characteristics of patients with SAT before their episodes, 120 healthy individuals who underwent thyroid ultrasonography during regular check-ups from 2019 to 2021 at CNUHH were selected for comparison. Subgroup analyses were performed on patients with SAT with and without the hypothyroid phase during their clinical course.ResultsThyroid volume was significantly greater in SAT patients at the first visit than in controls (p<0.05), and it decreased constantly throughout the follow-up period. Subgroup analysis showed that the initial thyroid volumes were similar in patients with SAT with and without the hypothyroid phase. However, SAT patients with the hypothyroid phase had significantly smaller thyroid volumes at the 1 month (p=0.025) and 3 month (p=0.006) follow-up visits. The reduction rate of the thyroid volume was significantly different within the first month (p=0.009).ConclusionA greater reduction in thyroid volume in SAT patients within 1 month of episode had a higher chance of developing a subsequent hypothyroid phase, which can lead to persistent hypothyroidism. Serial thyroid ultrasonography in patients with SAT, especially within the first month, may help in predicting the disease course of SAT.

Palpitations and Fatigue Post COVID: A Harbinger of Silent Thyroiditis!

Background: Subacute thyroiditis is a self-limiting condition brought about by an inflammatory reaction often linked to a recent viral infection. SARS-COV2 (COVID-19), an RNA coronavirus that started a global pandemic in December 2019 has been linked mostly to severe acute respiratory distress syndrome. However, there have been increasing reports of its effect on other organ systems. We present a case of a 32-year-old female recovering from COVID-19, only to develop silent thyroiditis afterwards. Clinical Case: A 32-year-old female with anxiety disorder but otherwise in excellent health was diagnosed with COVID-19 via nasal swab RT-PCR after experiencing low grade fever and cough. She quarantined at home and was on her way to recovery when, a few weeks later, she began to experience increasing bouts of chest pain with no relation to activity, intermittent headaches and lower extremity edema. This prompted her to visit the emergency department. Work-up done at that time was unremarkable and her symptoms were attributed mostly to anxiety. She was advised to follow-up as an outpatient with a cardiologist. One month later, due to the persistence of her fatigue, low exercise tolerance and tremors, she decided to seek consult with a cardiologist. An electrocardiogram done during that visit showed normal sinus rhythm with poor-R wave progression and early repolarization changes. Both the echocardiogram and 24-hour Holter monitoring, which were subsequently done, were unremarkable. Blood work-up, however, revealed a significantly low thyroid stimulating hormone (TSH) level of 0.17 mU/L, for which she was referred to an endocrinologist. A month later, she sought consult with an endocrinologist. Thyroid gland was non-tender on palpation. Repeat blood work-up showed an elevated TSH level (23.50 mU/L) with a low Free T4 (0.42 ng/dL) and an elevated thyroid peroxidase antibody (TPO-Ab) level (900 mU/mL), indicative of subacute thyroiditis, but without associated neck pain. Thyroid sonography done showed diffusely heterogeneous thyroid lobes with no evidence of a dominant mass or nodule. A decision was made to start her on low dose levothyroxine. Two months into treatment, she underwent repeat thyroid hormone levels. Normal TSH and normal free T4 were observed. However, TPO-Ab was still elevated. It was decided to continue her therapy for one more month before gradually tapering her levothyroxine dose. She was told to follow-up in a month for further monitoring. Conclusion: Subacute thyroiditis associated with COVID-19 infection has become a more common occurrence as more cases of COVID-19 are noted worldwide. Our patient followed the usual course of subacute thyroiditis, initially presenting with a thyrotoxicosis phase which typically lasts 4-10 weeks, then subsequently developing hypothyroidism, inadvertently needing thyroid hormone replacement. What made this case more intriguing was that she did not have severe anterior neck pain, the classic clinical presentation of subacute thyroiditis. While there is a very strong association between COVID-19 and respiratory failure, there is paucity of evidence linking COVID-19 to dysfunction of other body systems. This case of thyroiditis presenting post COVID-19 illness, buttresses the versatility of COVID-19. Physicians should keep this in mind when evaluating a COVID-19 survivor who continue to present with persistent tachycardia or palpitations with or without anterior neck pain even after a month or two from infection. Routine follow-up TSH assay on COVID-19 survivors may be a valuable consideration.

Application value of tissue dispersion quantitative analysis technique in different stages of SAT

Objective To investigate the application value of the ultrasonic elastic tissue dispersion quantitative analysis technique in different stages of subacute thyroiditis (SAT). Methods One hundred and forty-four SAT lesions detected from 81 patients were enrolled in the patient group. They were further divided into three subgroups, including acute group (group Ⅰ), medium group (group Ⅱ) and recovery group (group Ⅲ). Another 59 healthy volunteers were collected as control group. All the participants accepted conventional ultrasound and elastographic examinations. Eleven parameters were obtained by the tissue dispersion quantitative analysis software. These parameters were compared between groups and among subgroups by ANOVA. The correlation between all the parameters and the course of SAT were analyzed by Spearman and Multiple linear regression methods. Results Between groups and among subgroups, the complexity (COMP) and correlation (CORR) were not statistically different(all P>0.05). Differences of kurtosis (KURT) and angular secon moment (ASM) among the three subgroups were not significant (all P>0.05). Differences between groups and among subgroups were significantly different among the value of all the other seven indexes (all P<0.01). Moreover, they were all correlated with the clinical staging, with the highest coefficient in area ration of low-strain region (%AREA)(r=-0.881). Regression model was constructed and only %AREA was selected into the regression equation. ROC curves were constructed to estimate the clinic value of %AREA in staging patients of SAT, the areas under ROC curves were 0.986(group Ⅰ vs group Ⅱ-Ⅲ) and 0.988 (group Ⅰ-Ⅱ vs group Ⅲ) for %AREA, respectively. Conclusions The tissue dispersion quantitative analysis technique is helpful in estimating the stiffness of thyroid in patients with SAT. Key words: Ultrasonography; Thyroiditis, subacute; Tissue dispersion quantitative analysis technique

真性红细胞增多症患者干扰素治疗中合并亚急性甲状腺炎一例报告并文献复习

目的：报道真性红细胞增多症(PV)患者干扰素α(IFNα)治疗中合并亚急性甲状腺炎1例，初步探讨该类干扰素诱导的甲状腺炎(IIT)的临床特征，加深对IFNα不良反应的认识。方法：对本例患者的临床资料进行分析，并复习相关文献。结果：本例IIT的临床特征：1) 年轻女性，治疗前甲状腺自身抗体阴性，属于非自身免疫性IIT；2) 第一次亚甲炎发生于IFNα治疗2月时，第二次发生于IFNα治疗4月时；3) IIT的发生似乎与干扰素的剂型无关；4) IIT症状有轻有重，但是可控的，多数可以完成疗程；5) 中断后重新应用IFNα治疗时可再次发生甲状腺炎。结论：IFNα治疗中可出现甲状腺炎或甲状腺功能异常的不良反应。在血液系统疾病应用IFNα治疗时应严密监测甲状腺功能和甲状腺自身抗体。根据临床症状轻重决定是否停用IFNα，多数可继续使用，若停用后再次开始治疗时一定要严密监测甲状腺功能。 Object: A case of subacute thyroiditis associated with interferon therapy of polycythemia vera is reported. To explore the clinical features of interferon induced thyroiditis and to deepen the understanding of IFNα’s side effects. Methods: The clinical data of this patient were analyzed and related literatures were reviewed. Results: 1) The patient is a young woman.IIT manifested as non-autoimmune thyroiditis without TAb’s. 2) The first course of subacute thyroiditis was diagnosed in treatment 2 months and the second course was diagnosed in treatment 4 months. 3) It seems that there’s no association between different forms of interferon and IIT. 4) The symptoms of IIT were mild or severe, but they could be controlled. Most of them can complete the course of treatment. 5) Patients frequently developed recurrent thyroiditis when re-treating with IFNα. Conclusions: One of the side-effects of IFNα therapy is thyroiditis or thyroid dysfunction. IFNα therapy of hematological diseases should undergo routine thyroid screening. IFNα therapy should be treated based on the clinical presentation. IFNα therapy can be continued in most cases. Thyroid functions should be carefully monitored if treatment is resumed.

Subacute Thyroiditis Manifesting as a Thyroid Mass, Vocal Cord Paralysis, and Hypercalcemia

Objective To report a case of subacute thyroiditis manifesting as a thyroid mass, vocal cord paralysis, and hypercalcemia. Methods We describe the clinical, laboratory, and radiologic findings in a patient with an unusual clinical course of subacute thyroiditis. Results A 65-year-old woman presented with a hoarse voice and an enlarging tender mass in the right side of the neck. On admission, thyroid function was consistent with thyrotoxicosis from subacute thyroiditis. Laboratory studies showed a corrected serum calcium concentration of 11.4 mg/dL, intact parathyroid hormone of 125 pg/mL, 25-hydroxyvitamin D of 12 ng/mL, and creatinine of 1.8 mg/dL. Computed tomography of the neck without use of a contrast agent showed a heterogeneous mass in the right side of the neck in conjunction with deviation of the trachea from right to left but without invasion of the trachea. Thyroid ultrasonography disclosed a heterogeneous mass in the right thyroid lobe measuring 4.7 cm by 5.5 cm by 4.5 cm. Flexible laryngoscopy revealed right vocal cord paralysis. Treatment with a course of prednisone yielded normalization of the serum calcium level, improvement in her voice, and a decrease in size of the thyroid mass. Four months after initial presentation of the patient, thyroid hormone levels became normal, she was clinically euthyroid, and she had a full recovery of her voice. Her serum calcium concentration was normal (9.8 mg/dL) in association with a near-normal parathyroid hormone level of 90 pg/mL. The 25-hydroxyvitamin D and creatinine values were also normal. Repeated thyroid ultrasonography showed a smaller right thyroid lobe with a dominant nodule measuring 2.0 cm by 1.3 cm by 1.4 cm in the right upper pole. Conclusion This case illustrates that subacute thyroiditis can have the unusual initial manifestations of a thyroid mass, vocal cord paralysis, and hypercalcemia. In similar patients, a trial of corticosteroid therapy may be warranted in an effort to improve clinical symptoms and thus avoid unnecessary surgical treatment. (Endocr Pract. 2012;18:e17-e20)

Riedel's Thyroiditis in a Patient with Recurrent Subacute Thyroiditis: A Case Report and Review of the Literature

Riedel's thyroiditis is a rare form of chronic thyroiditis, characterised by a fibroinflammatory process that partially destroys the thyroid and often involves surrounding tissues. The relationship of Riedel's thyroiditis to other forms of thyroiditis is not clear. A case of Riedel's thyroiditis in a 51-year-old woman presenting with symptoms of subacute thyroiditis, is reported. She was diagnosed with subacute thyroiditis based on clinical manifestation and laboratory results. She was treated with glucocorticoids for six weeks, and then followed-up for 12 months. Three years later, she visited with tenderness and enlargement of thyroid mass, and laboratory and radiology findings suggested that she had a malignant thyroid tumor as well as subacute thyroiditis. After thyroidectomy, histopathologic findings showed that she had Riedel's thyroiditis in the presence of subacute thyroiditis. Until now, few cases of Riedel's thyroiditis in patients with a history of subacute thyroiditis have been reported in the literature. Although the etiology of Riedel's thyroiditis is unknown, it may develop in the course of subacute thyroiditis.

A Rare Case of Subacute Thyroiditis Causing Thyroid Storm

Thyroid storm is a rare but potentially fatal condition that is most frequently associated with Graves' disease. We present the case of a young woman who presented in thyroid storm, later diagnosed as being due to severe subacute thyroiditis. We discuss the diagnostic approach to thyroid storm, the initial management, and eventual treatment and course of subacute thyroiditis. This case illustrates the necessity to include subacute thyroiditis in the differential diagnosis of severe thyrotoxicosis and thyroid storm.

Subacute thyroiditis as seen initially in ENT department--a report of 30 cases.

To assess the pharyngeal presentations and the diagnostic value of thyroid SPECT and thyroid fine needle aspiratory biopsy (FNAB) in subacute thyroiditis (SAT) as seen initially in ENT department, 30 patients, during the course of SAT, were examined for pharyngeal symptoms and tested for serum T3, T4 level. The thyroid SPECT imaging or thyroid FNAB were performed. Our results showed that, of the 30 patients, 21 had sore throat of various degrees, and 9 had abnormal sensation of throat. Six were diagnosed as having SAT by only SPECT, in the remaining 24, the final diagnoses was established by SPECT combined with FNAB. Two of them were finally diagnosed as having SAT by trial treatment with oral prednisone. It is concluded that sore throat and abnormal sensation of pharynx are the important presentations of SAT, and thyroid SPECT imaging and thyroid FNAB are valuable in diagnosing SAT.

Clinical characteristics of subacute thyroiditis classified according to human leukocyte antigen typing.

We investigated human leukocyte antigen (HLA) class I and class II antigens in 56 Japanese patients with subacute thyroiditis (SAT) who visited our out-patient clinic between 1988 and 1990. We found SAT to be associated with not only HLA-B35 (40 patients; P < 0.000001; relative risk, 18.02), but also with HLA-B67 antigens (9 patients; P < 0.00001; relative risk, 11.20). No heterozygotes of HLA-B35 or HLA-B67 were found in any of the 56 patients with SAT. Either HLA-B35 or HLA-B67 antigen is found in 87% of patients with SAT. When season of onset and clinical course of SAT were compared in the 49 patients with HLA-B35-positive SAT (B35-SAT) and HLA-B67-positive SAT (B67-SAT), we were able to identify certain characteristics: 1) B67-SAT often followed the course from transient thyrotoxicosis to a hypothyroid phase to a euthyroid phase [6 of 9 B67-SAT (67%) vs. 10 of 40 B35-SAT (25%); P < 0.05]; and 2) B67-SAT occurred mostly during the summer or autumn and at a higher rate than did B35-SAR [8 of 9 B67-SAT (89%) vs. 17 of 40 B35-SAT (43%)], whereas B35-SAT occurred throughout the year. We conclude that there are at least two types of SAT that can be classified by association with either HLA-B35 or HLA-B67 antigens.

Humoral autoimmune manifestation in subacute thyroiditis.

To study the autoimmune manifestations in subacute thyroiditis (SAT), the patterns of thyroid antibodies, thyroglobulin and circulating immune complexes were investigated in 10 patients during the course of the disease. Eight patients were thyrotoxic at diagnosis, and became euthyroid during recovery with a median observation of 8 months (4-30 months). Thyroid stimulating immunoglobulins were measured as TSH binding inhibiting immunoglobulins (TBII) and as thyroid stimulating antibodies (TSAb). TBII were present in all patients at least once during the observation period and remained detectable in six patients after recovery. TSAb were detected in three patients without relation to the hyperthyroid state. Thyroglobulin antibodies (TgAb) were present in four patients and persisted in three, while microsomal antibodies (MAb) were negative. Thyroglobulin (Tg) in the TgAb negative patients (n = 6) was high at diagnosis (median 229 micrograms/l, range 55-375) and fell rapidly during the course of SAT. Circulating immune complexes (CIC), which were found in all patients, reached maximal levels shortly after the onset of the disease and persisted after recovery. No correlation could be demonstrated between the different thyroid antibodies, and there was no clear relation between the levels of CIC and presence of the autoantibodies. However, the changes in CIC paralleled the changes in TBII, and it is suggested that immune complex formation is a major feature of the regulatory mechanisms controlling the immune responses in SAT.

Transitory subclinical and permanent hypothyroidism in the course of subacute thyroiditis (de Quervain).

Sixty-two patients affected with subacute thyroiditis (SAT) were followed for a mean period of 14 months (range 1-40), by monitoring thyroid hormone levels in basal condition, pituitary TSH reserve, antithyroglobulin (TgAb) and antimicrosomal antibodies ( MsAb ), in order to study the natural course of the disease and to characterize its intermediate phase. In the first phase the mean serum iodothyronine levels were within normal limits, nevertheless elevated T3 and T4 levels were detected in 34 (54%) and 20 (32%) patients, respectively. The next phase was characterized by normal serum iodothyronine levels; TRH stimulation test, however, showed a significant increase of pituitary TSH reserve in 35 (56%) patients. All parameters reverted gradually towards normal in all but 3 patients, who showed overt permanent hypothyroidism. TgAb and MsAb were positive in the early stage in 15 (24%) and 40 (64%) patients, respectively, disappearing at the end of the follow-up period in all but one patient; this particular patient belonged to the group of 3 patients affected with permanent hypothyroidism. Our data indicate that the onset of SAT is characterized by transient hyperthyroidism and that transient subclinical hypothyroidism characterizes the next phase. TRH stimulation test is required for the diagnosis of the latter and for the identification of the few who develop permanent hypothyroidism.

The conversion of thyroxine to triiodothyronine (T3) or to reverse T3 in patients with thyroid dysfunction

In order to clarify the conversion of thyroxine (T4) to triiodothyronine (T3) or to reverse T3 (rT3), serum concentrations of T4, T3, rT3, thyrotropin (TSH), thyroxine-binding globulin (TBG) and values of T3 uptake (T3 U) were measured in 61 hyperthyroid and 31 hypothyroid patients, 8 patients with subacute thyroiditis, and 40 normal subjects. Then, free T4 index (FT4I), T3/T4, rT3/T4, and rT3/T3 ratio were calculated. The rT3/T3 ratio was high in the hyperthyroid patients and low in the hypothyroid patients compared with that in the normal subjects. The ratio was positively related to serum T4, T3, rT3 levels, and FT4I in the patients and normal subjects. The regression equation was represented by rT3/T3 = 0.015[T4] + 0.083. No influences of serum TBG and age on the rT3/T3 ratio were observed. Our results indicated that thyroid hormones themselves could regulate the conversion of T4 to T3 or rT3 by activating 5-monodeiodinase in hyperthyroidism and by activating 5'-monodeiodinase and suppressing 5-monodeiodinase in hypothyroidism. Serum rT3 level was a more sensitive parameter than serum T4 or T3 for evaluating thyroid dysfunction. During the treatment with methimazole (MMI) or L-thyroxine and the natural course of subacute thyroiditis, serum T4 levels and rT3/T3 ratios changed parallel to the regression line. However, once adverse effects of MMI occurred, those changed out of the line. From these results, we concluded that the relationship between serum T4 level and rT3/T3 ratio should be examined for adequate information concerning the peripheral conversion of thyroid hormones under various thyroid diseases.

Evolution of thyroid 127I stores measured by X-ray fluorescence in subacute thyroiditis.

Evaluation of the thyroid iodine content by x-ray fluorescence was performed in 13 patients throughout the course of subacute thyroiditis. In the initial hyperthyroid phase of the disease, the iodine stores of the thyroid were not completely depleted. The iodine content (6.5 +/- 3 mg) was about 2.5 times lower than normal values when thyroiditis had developed in a normal thyroid (10 patients); in 3 patients with goiter, it was elevated (29.6 +/- 6.7 mg) but was still within the normal range of euthyroid goitrous patients. After clinical remission, the iodine content of the gland increased only in two patients (+105% and +43% over the initial value, respectively). For the other patients, the iodine content decreased (from -5% to -100% of the initial value). Restoration of iodine stores occurred subsequently and appeared to be a slow and progressive phenomenon; in six patient, the iodine content was still below normal values 12 months after clinical remission (6.6 +/- 1.6 mg). These data suggest that the course of subacute thyroiditis might be longer than would appear from the clinical data, the hormonal assays, or the radioactive thyroid uptake data.

Subacute thyroiditis in a lateral thyroid gland: Evaluation of the pituitary-thyroid axis during the acute destructive and the recovery phases

Subacute thyroiditis in a lateral, ectopic thyroid has been previously unreported. A 4 10/12-YEAR-OLD GIRL HAD AN ENLARGING MASS IN THE LEFT UPPER ANTERIOR NECK. Initially, the serum concentration of T4 was normal, T3 was elevated, and TSH was undetectable without response to TRH. RAI uptake was 1%. The data were consistent with subacute thyroiditis. Twelve weeks later the serum concentration of T4 was low and TSH was elevated; thyroid replacement therapy was given for 20 weeks. When this was discontinued, there was an initial increase and then a decrease in the TSH values accompanied by an increase in serum concentrations of T3 and T4 to normal during eight weeks. One must consider a lateral ectopic thyroid gland in the differential diagnosis of masses in the neck. Physicians must be aware that temporary hypothyroidism occurs during the course of subacute thyroiditis.

Serum thyrotropin and thyroid hormones in the course of subacute thyroiditis.

ABSTRACT Three cases of subacute thyroiditis were observed throughout the course of the illness, in which serial measurements of protein-bound iodine (PBI), thyroxine (T4), triiodothyronine (T3), thyrotropin (TSH) and 24-hr thyroidal 131I uptake (131I uptake) were done. Suppressed TSH and 131I uptake were observed coincident with the elevation of PBI (or T4) and T3 during the acute phase. 131I uptake was hypernormal during the recovery phase, which was proceeded by the augmented secretion of TSH. In one subject, thyrotropin-releasing hormone (TRH) failed to produce TSH and T3 responses during acute phase. The elevations of TSH and T3 were observed with TRH during the recovery phase.

Thyroid function in subacute thyroiditis.

The status of thyroid function during the course of subacute thyroiditis has been assessed in 56 cases, 21 of which received no specific therapy to modify the natural course of the disease. In 11 very severe cases the initial extensive inflammatory necrosis presumably led to flooding of the body with thyroid hormone, thus producing symptoms of hyperthyroidism with a high level of serum protein-bound iodine (PBI), an increased basal metabolic rate and a profound depression of thyroidal I131 uptake to virtually zero. Following the acute phase the patient passed through a euthyroid interval into a phase characterized by symptoms of hypothyroidism with a low level of serum PBI. During the later part of this phase the ability of the gland to concentrate iodine began to increase. During the recovery phase, the thyroidal I131 uptake rose to levels above normal in a rebound phenomenon, whereas the serum PBI gradually rose to levels that did not exceed the normal range. In 15 moderately severe cases, the acute pha...