The prevalence of positive thyroid autoantibodies in patients with subacute thyroiditis: a systematic review and meta-analysis.

PURPOSE: Subacute thyroiditis (SAT) is a transient inflammatory disorder of the thyroid gland with a possible viral etiology. We conducted this study to estimate the pooled prevalence of thyroid autoantibodies in SAT patients. This question arose due to the varying reports on the positivity rates of thyroid autoantibodies among SAT patients. METHODS: We searched PubMed, Embase, Scopus, and Web of Science from their inception until March 25th, 2023. Observational studies reporting the positivity rate of thyroid autoantibodies for more than ten patients were included. We used the Joanna Briggs Institute's (JBI) critical appraisal checklist to assess the quality of the included studies. Pooled prevalence estimates with 95% confidence intervals were calculated using the random effects model. Subgroup analyses were performed to find sources of heterogeneity. RESULTS: Out of 1373 identified records, 32 studies involving 2348 SAT patients were included in our study. Thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) were positive in 22.8% and 12.2% of patients, respectively. The Study design, mean erythrocyte sedimentation rate and mean thyroid-stimulating hormone of patients were identified as sources of heterogeneity. As our secondary objectives, we found a recurrence rate of 14.7% and permanent hypothyroidism in 11.6% of patients. CONCLUSION: The results of our study revealed a low TPOAb positivity rate in SAT patients, consistent with its non-autoimmune etiology. The TgAb positivity rate in SAT patients was higher than that of the general population, possibly explained by the transient release of thyroglobulin into the bloodstream during the thyrotoxic phase, leading to subsequent TgAb production. Furthermore, our findings demonstrate a notable recurrence rate and permanent hypothyroidism among SAT patients, highlighting the importance of ongoing follow-up care.

Characteristics of patients with subacute thyroiditis.

INTRODUCTION: The diagnosis and management of subacute thyroiditis (SAT) may be challenging, and more evidence on patient and disease characteristics is warranted. METHODS: This was a retrospective cohort study of all patients in the North Denmark Region with a SAT diagnosis in the Danish National Patient Registry, 2016-2018. The medical records and biochemical results prior to the diagnosis and during a two-year follow-up period were reviewed. RESULTS: A total of 71 patients with a SAT diagnosis were identified, and the diagnosis was verified in 44 (62.0%) cases with an incidence rate of 2.4/100,000/year. Patients with verified SAT were predominantly females (72.7%) with a median age of 50.7 years. Biochemical results showed thyrotoxicosis at the initial examination in 69.8% and elevated C-reactive protein in 86.5% of patients. Longitudinal biochemical assessment showed a biphasic response (median thyroid-stimulating hormone, initially: 0.02 mIU/l, at three months: 4.7 mIU/l and 2.4 mIU/l after two years). Treatment with non-steroidal anti-inflammatory drugs, beta-blockers and/or prednisolone was initiated in 23 of the 38 patients (60.5%) evaluated, and ten of 33 patients (30.3%) with follow-up data received thyroid hormone replacement therapy. CONCLUSION: In the North Denmark Region, a hospital diagnosis of SAT was verified in less than two thirds of cases. Further large studies are warranted to extend the findings concerning the treatment and outcome of SAT. FUNDING: None. TRIAL REGISTRATION: Not relevant.

Beyond Acute COVID-19: Investigating the Incidence of Subacute Thyroiditis in Long COVID-19 in Korea.

BACKGRUOUND: The correlation between acute coronavirus disease 2019 (COVID-19) and subacute thyroiditis (SAT) has not been clearly investigated in "long COVID" patients. We aimed to investigate the incidence of SAT during convalescence and after the acute phase of COVID-19, comparing with that of the general population. METHODS: Data from a total of 422,779 COVID-19 patients and a control group of 2,113,895 individuals were analyzed. The index date was defined as the date 3 months after confirmation of COVID-19. The incidence rate (IR) of SAT and hazard ratios (HRs) were calculated per 100,000 persons. Subgroup analysis included analysis of HRs 90-179 and 180 days post-COVID-19 diagnosis; and additional analysis was conducted according to hospitalization status, sex, and age group. RESULTS: The IR of SAT was 17.28 per 100,000 persons (95% confidence interval [CI], 12.56 to 23.20) in the COVID-19 group and 8.63 (95% CI, 6.37 to 11.45) in the control group. The HR of COVID-19 patients was 1.76 (95% CI, 1.01 to 3.06; P=0.045). The HR of SAT was 1.39 (95% CI, 0.82 to 2.34; P=0.220) up to 6 months after the index date and 2.30 (95% CI, 1.60 to 3.30; P<0.001) beyond 6 months. The HR for SAT among COVID-19 patients was 2.00 (95% CI, 1.41 to 2.83) in hospitalized patients and 1.76 (95% CI, 1.01 to 3.06) in non-hospitalized patients compared to the control group. The IR of SAT was 27.09 (95% CI, 20.04 to 35.82) for females and 6.47 (95% CI, 3.34 to 11.30) for males. In the 19 to 64 age group, the IR of SAT was 18.19 (95% CI, 13.70 to 23.67), while the IR was 9.18 (95% CI, 7.72 to 10.84) in the 65 to 69 age group. CONCLUSION: SAT could be a potential long-term complication of COVID-19. Long-term surveillance for thyroid dysfunction is needed especially in hospitalized, female and young-aged subjects.

Subacute THYROiditis Related to SARS-CoV-2 VAccine and Covid-19 (THYROVAC Study): A Multicenter Nationwide Study.

CONTEXT: The aims of the study are to compare characteristics of subacute thyroiditis (SAT) related to different etiologies, and to identify predictors of recurrence of SAT and incident hypothyroidism. METHODS: This nationwide, multicenter, retrospective cohort study included 53 endocrinology centers in Turkey. The study participants were divided into either COVID-19-related SAT (Cov-SAT), SARS-CoV-2 vaccine-related SAT (Vac-SAT), or control SAT (Cont-SAT) groups. RESULTS: Of the 811 patients, 258 (31.8%) were included in the Vac-SAT group, 98 (12.1%) in the Cov-SAT group, and 455 (56.1%) in the Cont-SAT group. No difference was found between the groups with regard to laboratory and imaging findings. SAT etiology was not an independent predictor of recurrence or hypothyroidism. In the entire cohort, steroid therapy requirement and younger age were statistically significant predictors for SAT recurrence. C-reactive protein measured during SAT onset, female sex, absence of antithyroid peroxidase (TPO) positivity, and absence of steroid therapy were statistically significant predictors of incident (early) hypothyroidism, irrespective of SAT etiology. On the other hand, probable predictors of established hypothyroidism differed from that of incident hypothyroidism. CONCLUSION: Since there is no difference in terms of follow-up parameters and outcomes, COVID-19- and SARS-CoV-2 vaccine-related SAT can be treated and followed up like classic SATs. Recurrence was determined by younger age and steroid therapy requirement. Steroid therapy independently predicts incident hypothyroidism that may sometimes be transient in overall SAT and is also associated with a lower risk of established hypothyroidism.

Subacute thyroiditis following COVID-19: A systematic review.

Background: Subacute thyroiditis (SAT) is a self-limiting thyroid inflammatory disease occurring specifically after upper respiratory tract infections. Since COVID-19 is a respiratory disease leading to multi-organ involvements, we aimed to systematically review the literature regarding SAT secondary to COVID-19. Methods: We searched Scopus, PubMed/MEDLINE, Cochrane, Web of Science, ProQuest, and LitCovid databases using the terms "subacute thyroiditis" and "COVID-19" and their synonyms from inception to November 3, 2022. We included the original articles of the patients with SAT secondary to COVID-19. Studies reporting SAT secondary to COVID-19 vaccination or SAT symptoms' manifestation before the COVID-19 infection were not included. Results: Totally, 820 articles were retained. Having removed the duplicates, 250 articles remained, out of which 43 articles (40 case reports and three case series) with a total of 100 patients, were eventually selected. The patients aged 18-85 years (Mean: 42.70, SD: 11.85) and 68 (68%) were women. The time from the onset of COVID-19 to the onset of SAT symptoms varied from zero to 168 days (Mean: 28.31, SD: 36.92). The most common symptoms of SAT were neck pain in 69 patients (69%), fever in 54 (54%), fatigue and weakness in 34 (34%), and persistent palpitations in 31 (31%). The most common ultrasonographic findings were hypoechoic regions in 73 (79%), enlarged thyroid in 46 (50%), and changes in thyroid vascularity in 14 (15%). Thirty-one patients (31%) were hospitalized, and 68 (68%) were treated as outpatients. Corticosteroids were the preferred treatment in both the inpatient and outpatient settings (25 inpatients (81%) and 44 outpatients (65%)). Other preferred treatments were nonsteroidal anti-inflammatory drugs (nine inpatients (29%) and 17 outpatients (25%)) and beta-blockers (four inpatients (13%) and seven outpatients (10%)). After a mean duration of 61.59 days (SD: 67.07), 21 patients (23%) developed hypothyroidism and thus, levothyroxine-based treatment was used in six of these patients and the rest of these patients did not receive levothyroxine. Conclusion: SAT secondary to COVID-19 seems to manifest almost similarly to the conventional SAT. However, except for the case reports and case series, lack of studies has limited the quality of the data at hand.

Emerging trends and hot spots in subacute thyroiditis research from 2001 to 2022: A bibliometric analysis.

Background: Subacute thyroiditis (SAT) is the most prevalent self-limiting thyroid disease that causes pain, accounting for about 5% of all clinical thyroid disorders. Numerous clinically noteworthy results have been published in this area over the last 20 years. However, no article has comprehensively assessed the relevant literature yet. We conducted a bibliometric analysis of SAT to provide light on the dynamic nature of scientific advancement and aid researchers in gaining a global perspective while examining research core themes and hotspots. Methods: SAT-related articles and reviews from 2001 to 2022 were retrieved from the Science Citation Index-Expanded of Web of Science Core Collection (WoSCC). We analyzed current research trends and hotspots in this area using CiteSpace and Vosviewer. Results: A total of 568 studies associated with SAT research were published in 282 academic journals by 2,473 authors in 900 institutions from 61 countries/regions. The United States was a crucial link in inter-country/region collaboration and was the most frequently involved country in international cooperation. The University of Missouri System was the top organization, and Braley-Mullen H. was the most productive researcher. Thyroid published the most papers, with 36 publications. The most co-cited article was "Clinical features and outcome of subacute thyroiditis in an incidence cohort: Olmsted County, Minnesota, study" (by Fatourechi V., 2003). The clustered network and timeline view of keywords showed that the prevalence, diagnosis, and treatment of SAT were the research core themes during the past 20 years. Analysis of keyword bursts indicated that the clinical characteristic and the influence of COVID-19 on SAT appeared to be the current research hotspots. Conclusion: This bibliometric analysis conducted a thorough review of the SAT research. The clinical characteristics and the genetic background of SAT under the influence of COVID-19 are current research hotspots. However, there is still a need for further study and global collaboration. Our findings can aid researchers in understanding the current status of SAT research and immediately pinpoint new directions for further investigation.

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

PURPOSE: An 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. METHODS: This 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. RESULTS: The 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. CONCLUSION: With 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.

Evaluation of the diagnostic features and clinical course of COVID-19 vaccine-associated subacute thyroiditis.

OBJECTIVE: This study aimed to identify cases of coronavirus disease 2019 (COVID-19) vaccine-associated subacute thyroiditis (SAT) during the active vaccination period of the pandemic, analyze the characteristics of these cases, and compare them with cases of non-vaccine associated SAT diagnosed in the same period. METHODS: A total of 55 patients diagnosed with SAT in our outpatient clinic between February and October, 2021, were included in this retrospective single-center study. RESULTS: Of the study population, 16 (29.1%) were diagnosed with COVID-19 vaccine-associated SAT (10 with CoronaVac® and six with Pfizer-BioNTech® vaccine), with a median time to onset of symptoms after vaccination of 6.5 (range, 2-20) days. There was no statistically significant difference between the vaccine-associated (VA) and non-vaccine associated (NVA) groups in terms of age, gender, time to diagnosis, thyroid volumes, thyroid function tests, and acute phase reactants. Seven (43.8%) and 25 (64.1%) patients were treated with methylprednisolone in the VA group and NVA group, respectively (p = 0.16). Follow-up data of 45 patients (16/16 for VA and 29/39 for NVA) were available. The mean follow-up of these patients was 47.4 ± 19.4 days, and the follow-up periods of the VA group and NVA group were comparable (p = 0.24). There was no difference between the two groups in terms of the frequency of euthyroidism at the follow-up visit (12/16 vs.14/29, p = 0.08). CONCLUSION: With the increase in COVID-19 vaccination rates during the current pandemic, VA SAT cases are seen more frequently. The present study demonstrated that these cases have similar diagnostic features and clinical course to that of classic forms of SAT. In addition, most patients with VA SAT had a mild clinical course that improved with non-steroidal anti-inflammatory drugs.

Thyroid dysfunction following vaccination with COVID-19 vaccines: a basic review of the preliminary evidence.

PURPOSE: The safety and efficacy of the several types of COVID-19 vaccines, including mRNA-based, viral vector-based, and inactivated vaccines, have been approved by WHO. The vaccines can confer protection against severe SARS-CoV-2 infection through induction of the anti-spike protein neutralizing antibodies. However, SARS-CoV-2 vaccines have been associated with very rare complications, such as thyroid disorders. This review was conducted to highlight main features of thyroid abnormalities following COVID-19 vaccination. METHODS: A comprehensive search within electronic databases was performed to collect reports of thyroid disorders after vaccination with COVID-19 vaccines. RESULTS: Among 83 reported cases including in this review, the most cases of thyroid abnormalities were observed after vaccination with mRNA-based vaccines (68.7%), followed by viral vector vaccines (15.7%) and 14.5% cases following inactivated vaccines. Subacute thyroiditis (SAT) was the most common COVID-19 vaccination-related thyroid disease, accounting for 60.2% of all cases, followed by Graves' disease (GD) with 25.3%. Moreover, some cases with focal painful thyroiditis (3.6%), silent thyroiditis (3.6%), concurrent GD and SAT (2.4%), thyroid eye disease (1.2%), overt hypothyroidism (1.2%), atypical subacute thyroiditis (1.2%), and painless thyroiditis with TPP (1.2%) were also reported. Overall, in 58.0% of SAT cases and in 61.9% of GD cases, the onset of the symptoms occurred following the first vaccine dose with a median of 10.0 days (ranged: 3-21 days) and 10.0 days (ranged: 1-60 days) after vaccination, respectively. Moreover, 40.0% of SAT patients and 38.1% of GD patients developed the symptoms after the second dose with a median of 10.5 days (ranged: 0.5-37 days) and 14.0 days (ranged: 2-35 days) after vaccination, respectively. CONCLUSION: Fortunately, almost all cases with COVID-19 vaccination-associated thyroid dysfunctions had a favorable outcome following therapy. The benefits of COVID-19 vaccinations in terms of terminating the pandemic and/or reducing mortality rates can exceed any risk of infrequent complications such as a transient thyroid malfunction.

Subacute thyroiditis during the COVID-19 pandemic: a prospective study.

PURPOSE: Subacute thyroiditis(SAT) is a destructive thyroiditis associated with viral infections. Several SAT cases associated with SARS-CoV-2 infection/vaccination were recently reported. We aimed to evaluate prospectively all cases applied to our tertiary center and their relationship with SARS-CoV-2 during 16 months of the pandemic. Cases during similar pre-pandemic period were recorded for numeric comparison. METHODS: Prospective study took place between March 2020 and July 2021. SAT was diagnosed by classical criteria. Swabs for SARS-CoV-2 and a wide respiratory viral panel (RV-PCR) were taken. Previous COVID-19 was assessed by SARS-CoV-2 IgM&IgG levels. Study group was divided into three as: CoV-SAT, patients who had or still have COVID-19, Vac-SAT, patients diagnosed within three months after SARS-CoV-2 vaccination and NonCoV-SAT, those not associated with COVID-19 or vaccination. RESULTS: Out of 64 patients, 18.8% (n = 12) was classified as CoV-SAT, 9.3% (n = 6) as Vac-SAT and 71.9% as (n = 46) NonCoV-SAT. SARS-CoV-2 RT-PCR tests on the diagnosis of SAT were negative in all, but two patients tested positive five days later, in second testing, performed upon clinical necessity. CoV-SAT and NonCoV-SAT groups were similar in terms of clinical, laboratory, and treatment characteristics. However, symptoms were milder and treatment was easier in Vac-SAT group (p = 0.006). CONCLUSIONS: Total number of SAT cases during the pandemic period was comparable to pre-pandemic period. However, a considerable rate of SARS-CoV-2 exposure in SAT patients was established. COVID-19 presented with SAT, as the first manifestation in three cases. Vaccine-related cases developed in a shorter time period, clinical presentation was milder, and only a few required corticosteroids.

Risk factors, treatment and outcomes of subacute thyroiditis secondary to COVID-19: a systematic review.

BACKGROUND: COVID-19 is known to cause an acute respiratory illness, although clinical manifestations outside of the respiratory tract may occur. Early reports have identified SARS-CoV-2 as a cause of subacute thyroiditis (SAT). METHODS: A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE, Web of Science and PubMed databases were queried in February 2021 for studies from December 2019 to February 2021. MeSH search terms 'COVID-19', 'SARS-CoV-2' and 'coronavirus' along with search terms 'thyroiditis', 'thyrotoxicosis' and 'thyroid' were used. Descriptive statistics for continuous variables and proportions for categorical variables were calculated. RESULTS: Fifteen publications reporting on 17 individual cases of COVID-19-induced SAT were identified. Age ranged from 18 to 69 years. The majority (14 of 17; 82%) of cases were female. The delay between onset of respiratory symptoms and diagnosis of SAT ranged from 5 to 49 days (mean, 26.5). Systemic inflammatory response syndrome related to viral infection was uncommonly reported at the time of SAT diagnosis. Thyroid ultrasonography frequently reported an enlarged hypoechoic thyroid with decreased vascularity and heterogenous echotexture. Elevated C-reactive protein (CRP) was common at the time of SAT diagnosis, with results ranging from 4.5 to 176 mg/L (mean, 41 mg/L). Antithyroid antibodies were frequently negative. SAT-specific treatment included corticosteroids for 12 of 17 (70.5%) patients. Most returned to normal thyroid status. CONCLUSION: COVID-19-associated SAT may be difficult to identify in a timely manner due to potential absence of classic symptoms, as well as cross-over of common clinical features between COVID-19 and thyrotoxicosis.

Incidence of De Quervain's thyroiditis during the COVID-19 pandemic in an area heavily affected by Sars-CoV-2 infection.

PURPOSE: To evaluate the possible association between Covid-19 infection and subacute thyroiditis. METHODS: We reviewed the medical and imaging records of patients referred to our Department's outpatient setting dedicated to 'thyroid emergency' (records with a 'bollino verde'-green sticker, classifed as urgent) from April 2020 to October 2020. This outpatient clinic is devoted to patients requiring evaluation for severe hypothyroidism, thyrotoxicosis and neck discomfort or pain. All patients with a newly-diagnosed subacute thyroiditis were selected. The data of all patients receiving a diagnosis of subacute thyroiditis was collected retrospectively, taking into account the same period of time (April-October) and starting from 2016. RESULTS: During the COVID-19 outbreak in our region (April 2020 to October 2020) 396 patients attended the outpatient emergency clinic. Among them, 10 (2.5%) patients received a diagnosis of subacute thyroiditis. In a single patient, a 44-year-old man, a COVID-19 pulmonary infection had been diagnosed 7 weeks before the diagnosis of subacute thyroiditis. All of the remaining patients were and remain COVID-19 free as confirmed by telephone interview. The percentage of patients who received a diagnosis of subacute thyroiditis in the same period starting from 2016 was very similar (2.9%, 2.9%, 2.6% and 3.0% in 2016, 2017, 2018 and 2019, respectively). CONCLUSIONS: Our data do not show an increase in the incidence of subacute thyroiditis in the Brescia area, a region with the highest prevalence of COVID-19 in Italy during the period of the pandemic outbreak.

New aspects in the pathogenesis and management of subacute thyroiditis.

Subacute thyroiditis (SAT) is a thyroid inflammatory disease, whose pathogenesis and determinants of the clinical course were unclear for many decades. The last few years have brought many clinically significant new data on the epidemiology, pathogenesis and management of SAT. Several human leukocyte antigen (HLA) alleles were demonstrated not only to increase the risk of SAT, but also to correlate with SAT clinical course and determine the risk of recurrence. The world-wide epidemic of the coronavirus disease 19 (COVID-19) has provided new observations that the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) can be a potent SAT-triggering factor, and that the clinical course of SAT in patients affected by COVID-19 is different from a typical one. Additionally, many new trends in the clinical course are emerging. In the last years, painless course of SAT is more and more often described, constituting a special challenge in patients hospitalized due to COVID-19. Despite an excellent availability of diagnostic methods, several difficulties in SAT differential diagnosis can be currently encountered and the proper diagnosis and treatment is frequently delayed. False positive diagnoses of SAT in patients with malignancies of poor prognosis constitute a life-threatening problem. Taking into account all the new aspects of SAT pathogenesis and of its clinical course, the new - modified - SAT diagnosis criteria have been proposed.

Risk Factors for Subacute Thyroiditis Recurrence: A Systematic Review and Meta-Analysis of Cohort Studies.

Background: Subacute thyroiditis (SAT) is a self-limited inflammatory thyroid disease with recurring episodes. However, the results regarding the recurrence rate and risk factors for SAT are inconsistent. This meta-analysis aimed to summarize the evidence of the recurrence rate and the risk factors for SAT. Methods: The present study involved the performance of a systematic literature search of all English studies published in PubMed, Embase, Web of Science, and The Cochrane Library from inception to August 20, 2021. Cohort studies that reported the SAT recurrence rate and risk factors for recurrence were included. Two independent investigators extracted relevant information. Fixed- and random-effects models were used to pool effect sizes based on study heterogeneity. Results: Eighteen cohort studies were identified. The pooled findings showed that the recurrence rate was 12.0% (95% CI: 8.2%, 17.1%). The risk of recurrence in the glucocorticoids group was higher than that in the NSAIDs group (RR = 1.84, 95% CI: 1.04, 3.24). However, there was no significant difference in age or sex between the recurrence group and the non-recurrence group. Findings from one or two cohort studies also indicated that the copresence of HLA-B*18:01 and -B*35, the number of days required to taper prednisolone (PSL) to 5 mg/day, the duration of disease before treatment less than 30 days, the sialic acid level, or the TSH level at the termination of treatment and further extension of the hypoechoic area and increase in thyroid volume were related to the recurrence of SAT. Conclusion: Recurrence was common in SAT patients. The present study indicated that glucocorticoid treatment was associated with a higher recurrence rate of SAT than NSAIDs treatment. The clinical implications of this association should be interpreted with caution, and further clinical trials on the long-term effects of different treatment strategies are needed.

Eosinophil/Monocyte Ratio Combined With Serum Thyroid Hormone for Distinguishing Graves' Disease and Subacute Thyroiditis.

Background: Thyrotoxicosis is commonly classified into several entities according to different etiologies. Identifying the causes of thyroid dysfunction is critical for the subsequent selection of treatment. The free triiodothyronine to free thyroxine ratio (fT3/fT4) is widely used but is still a controversial diagnostic measurement. Methods: A total of 290 patients including 141 healthy control subjects, 86 patients with untreated Graves' disease (GD,) and 63 patients with subacute thyroiditis (SAT) were enrolled in the study. The main aim was to evaluate the diagnostic value of different indexes from serum testing including fT3, fT4, eosinophils (Eo) and monocytes (Mo). The diagnostic performance of multiple indexes was evaluated separately using receiver operating characteristic curve analysis. Results: Sensitivities and specificities of fT4/fT3, Mo/Eo ratios and Mo/Eo ratio + fT4/fT3 for diagnosing GD were 80.23 and 88.89, 82.56 and 60.32, and 74.4 and 87.3 with cut-off values of ≤ 2.841, ≤ 8.813 and >0.644, respectively. An equation of combined indicators including Mo, Eo, fT3, and fT4 data was developed to calculate a probability value and among all indexes studied the indicator combination formula gave the best diagnostic value, reaching sensitivity and specificity of 89.53 and 90.48%, respectively, with an optimum cut-off value at 0.561 for GD diagnosis. Conclusion: Compared to regular indexes (fT4/fT3 and Mo/Eo), a newly developed indicator combination formula provided a higher prediction probability and may serve as a simple, cost-effective tool for differentiating GD from SAT patients, especially in undeveloped regions of China.

The Detection of Serum IgMs to Thyroglobulin in Subacute Thyroiditis Suggests a Protective Role of IgMs in Thyroid Autoimmunity.

CONTEXT: The role of serum immunoglobulin (Ig)Ms in autoimmune thyroid diseases is uncertain. OBJECTIVE: We looked for IgMs to thyroglobulin (Tg) in patients with subacute thyroiditis (SAT), which is characterized by high serum Tg levels, the possible de novo appearance of IgGs to Tg (TgAb-IgGs), and no autoimmune sequelae. MAIN OUTCOME MEASURES: TgAb-IgMs and TgAb-IgGs were detected by binding to Tg using the enzyme-linked immunosorbent assay (ELISA). The upper reference limit of TgAb-IgMs and TgAb-IgGs was established in 40 normal subjects. We looked for TgAb-IgMs in 16 patients with SAT, 11 with Hashimoto's thyroiditis (HT), and 8 with Graves' disease (GD) who were all positive for TgAb-IgGs. IgM binding to bovine serum albumin (BSA), keyhole limpet hemocyanin (KLH), and glucagon in ELISA was measured. Inhibition of TgAb-IgMs binding to coated Tg was evaluated by preincubating serum samples or IgG-depleted samples with soluble Tg. RESULTS: TgAb-IgMs were positive in 10/16 patients with SAT, 2/11 with HT, and 1/8 with GD. TgAb-IgMs were higher in SAT (0.95; 0.42-1.13) (median; 25th-75th percentiles) than in HT (0.47; 0.45-0.51) and GD patients (0.35; 0.33-0.40) (P < .005 for both). IgM binding of SAT sera to BSA, KLH, and glucagon was significantly lower than Tg. Preincubation with soluble Tg reduced the binding of IgMs to coated Tg by 18.2% for serum samples and by 35.0% and 42.1% for 2 IgG-depleted samples. TgAb-IgM levels were inversely, although nonsignificantly, correlated with Tg concentrations. CONCLUSIONS: Tg leak associated with thyroid injury induces the production of specific TgAb-IgMs, which, in turn, increases the clearance of Tg and might prevent the establishment of a persistent thyroid autoimmune response.

The Importance of Vitamin D Level in Subacute Thyroiditis Disease and the Effect of Vitamin D on Disease Prognosis.

OBJECTIVE: Subacute thyroiditis (SAT) is an inflammatory thyroid disease that manifests with severe pain. The presence of the vitamin D receptor in immune system cells shows that vitamin D deficiency can trigger inflammatory diseases. The aim of the present study was to determine the prevalence of vitamin D deficiency in SAT patients, and the relationship between vitamin D level and permanent hypothyroidism and recurrence rate. METHODS: In this retrospective study, 25-hydroxyvitamin D (25[OH]D) levels of 170 SAT patients and 86 control subjects were compared. RESULTS: The 25(OH)D levels were significantly lower in the SAT patients, and there was no seasonal difference. A negative correlation was determined between the erythrocyte sedimentation rate and 25(OH)D, but no significant relationship was found between vitamin D level and prognosis. CONCLUSION: As a result of this study, it was shown that vitamin D levels in subacute thyroiditis patients were significantly lower than in the healthy control group. Although there is no relationship between vitamin D level and disease prognosis, vitamin D deficiency may increase the rate of respiratory tract infections (especially, influenza, coxsackievirus, measles, adenovirus, retroviruses) and eventually SAT development.

Long-term Outcome of Subacute Thyroiditis.

BACKGROUND: Subacute thyroiditis (SAT) is a rare inflammatory disease that presents diagnostic challenges. The underlying pathophysiology and prediction of outcomes are elusive. We investigated the long-term follow-up of SAT for up to 30 years and determined predictors for later hypothyroidism. METHODS: SAT outcome data from 127 patients (age: 47.6 ± 11.0 yrs. , BMI: 24.7±4.8 kg/m²) were analyzed retrospectively. Patients with pre-existing and known causes of hypothyroidism unrelated to SAT were excluded. We also excluded patients without an accelerated erythrocyte sedimentation rate. SAT outcome parameters included anterior neck pain or tenderness of the thyroid, inflammation markers, hypoechoic areas in thyroid ultrasound, hyperthyroidism, fine-needle aspiration, and thyroid scan. Pre-treatment TSH-levels, gender, age, ultrasound findings, anti-thyroid antibodies and markers of inflammation were considered as possible predictors of SAT outcome. RESULTS: More than 26.8% of SAT patients developed permanent hypothyroidism within 3 years of treatment. The patient groups later developing hypothyroidism did not differ in age, BMI, pre-treatment TSH levels or initial dosage of prednisolone treatment. However, high cumulative doses of prednisolone were associated with a higher prevalence of hypothyroidism. Also, women were more likely to develop hypothyroidism (OR: 3.18 (95% CI: 1.14-8.65); p=0.0176). CONCLUSIONS: Our study suggests that one-quarter of patients with SAT develop hypothyroidism in the long-term. Hypothyroidism was predicted by high cumulative doses of prednisolone treatment and female gender. The reported lower prevalence of hypothyroidism in other countries may represent the faster establishment of diagnosis, different treatment protocols, or lower susceptibility to loss of thyroid function. Swift establishment of the diagnosis and rapid tapering of steroids may result in a higher proportion of patients with euthyroidism.