The role of severity and duration of inflammation and hematological parameters on the outcome of subacute thyroiditis.

Background: The role of severity and duration of inflammatory findings on the development of persistent hypothyroidism and anemia has not been clarified in subacute thyroiditis (SAT). Methods: Demographic data and laboratory parameters of patients with SAT were analyzed retrospectively. Results: Permanent hypothyroidism was observed in 28.1% of patients. Baseline elevated erythrocyte sedimentation rate as defined >74.5 mm/h was found to be associated with permanent hypothyroidism, but the duration of inflammation was not different between the recovered and hypothyroid patients. Baseline hemoglobin values improved without specific therapy in 3.5 months. Conclusion: The initial severity but not the duration of inflammation increases the risk for the development of permanent thyroid dysfunction, and anemia improves with the resolution of inflammation.

[Box: see text].

Subacute thyroiditis in the SARS-CoV-2 era: a multicentre prospective study.

Objective: Many cases of subacute thyroiditis (SAT) have been described related to SARS-CoV-2 infection, but no prospective data about follow-up are known. This prospective, longitudinal, 3-year, multicentre study aims to explore the clinical peculiarities and outcome of SAT in relation to SARS-CoV-2 infection, ascertained with antibody dosage. Methods: All patients receiving SAT diagnosis from November 2020 to May 2022 were enrolled. Data on anamnesis, physical examination, blood tests (TSH, freeT4, freeT3, thyroglobulin, anti-thyroid antibodies, C-reactive protein, erythrocyte sedimentation rate, complete blood count), and thyroid ultrasound were collected. At baseline, the presence of IgG against the SARS-CoV-2 spike protein or nucleocapsid was investigated. Patients were evaluated after 1, 3, 6, and 12 months. Results: Sixty-six subjects were enrolled. At baseline, 54 presented with pain, 36 (67%) for at least 15 days. Serum SARS-CoV-2 IgG measurements documented that 7 out of 52 subjects (13.5%) had infection before SAT diagnosis (COVID+). No significant differences between the COVID+ and COVID- groups were found at baseline, except for respiratory symptoms and fever, which were more common in COVID+ (P = 0.039 and P = 0.021, respectively). Among the 41 subjects who completed follow-up, COVID+ and COVID- did not differ for therapeutic approach to SAT or outcome, all having an improvement in neck pain, inflammation parameters, and ultrasound features. Conclusion: This is the first prospective study investigating any difference both at diagnosis and at follow-up between SAT presentation in patients with previous SARS-CoV-2 infection and those without. Our data demonstrate that SARS-CoV-2 does not impact on SAT onset, evolution, and outcome.

The Effects of Corticosteroid and Nonsteroid Anti-Inflammatory Therapies on Permanent Hypothyroidism Occurring After the Subacute Thyroiditis.

OBJECTIVE: Subacute thyroiditis(SAT) is an acute inflammatory, self-limited, and destructive disease of the thyroid gland. Although it is a temporary disease, it has permanent consequences. We aim to investigate the influences of the treatment choice on permanent hypothyroidism occurring after SAT and whether there are predictive factors for the development of permanent hypothyroidism. METHODS: We retrospectively investigated 57 SAT patients admitted to our tertiary hospital between 2017 and 2019. After excluding 6 patients, demographic, clinical, laboratory, and imaging findings of 36 patients treated with NSAIDs and 15 patients treated with corticosteroids were compared. The median duration of follow-up was 4 (3.5-5.5) years. RESULTS: Permanent hypothyroidism occurred in 16 patients (31.4%) of 51 patients. It developed at a significantly higher rate in NSAID users (p=0.019). There was no significant difference in the occurrence of transient hypothyroidism and recurrence (p=0.472, p=0.082). The early maximum TSH values were strongly associated with permanent hypothyroidism. The Odds Ratio (OR) value was 2.59 (95% CI = 1.26 - 5.33, p=0.009), Nagelkerke R2 = 0.821. The early maximum TSH level had a predictive value, with an AUC of 0.966 for post-SAT permanent hypothyroidism (p<0.001). The cutoff values for the early maximum TSH were 9.07uIU/ml (81.3% sensitivity, 100% specificity), and 7.05 uIU/ml (87.5% sensitivity, 94.3% specificity). CONCLUSION: Corticosteroid therapy is significantly effective in preventing permanent hypothyroidism from developing after SAT. The early maximum TSH values are an indicator for the prediction of the development of permanent hypothyroidism.

The relationship between serum calprotectin levels and disease activity in patients with subacute thyroiditis.

OBJECTIVE: Increased calprotectin (S100A8/A9) levels have been demonstrated in many acute and chronic inflammatory processes. Subacute thyroiditis is an inflammatory disease of the thyroid gland. In our study, we investigated the value of this inflammation marker in the diagnosis and follow-up of subacute thyroiditis. PATIENTS AND METHODS: Patients with subacute thyroiditis admitted to our clinic between November 2018 and January 2020 were included in the study. In the acute phase of the disease, fT4 (free thyroxin), TSH (Thyroid Stimulant Hormone), CRP (C Reactive Protein), ESR (Erythrocyte Sedimentation Rate), ALT (Alanine Aminotransferase), AST (Aspartate Aminotransferase), Creatinine, WBC (White Blood Cell), Absolute Lymphocyte and Neutrophil Count (ALC, ANC) parameters were detected and recorded. After complete resolution of the disease, the same laboratory parameters and acute phase reactants were again detected. Additionally, Calprotectin determination was performed in the acute phase and recovery period. Persistent hypothyroidism was determined by 6th-month TSH levels. RESULTS: Thirty-six patients were included in the study. Along with the classical acute phase reactants and ANC, there was a significant increase in the Calprotectin levels in the acute inflammatory phase of the disease compared to the recovery period (96. 92-37.98, p<0.001). Neither classical acute phase reactants and nor calprotectin were found to have a significant effect on the development of permanent hypothyroidism. Calprotectin did not correlate with other acute phase reactants, absolute neutrophil count and TSH levels in both the acute phase and resolution period. CONCLUSIONS: Calprotectin appears to be an important marker in the diagnosis and follow-up of subacute thyroiditis.

COVID-19: A Potential Trigger for Thyroid Dysfunction.

Subacute thyroiditis (SAT) is a self-limiting thyroid dysfunction of viral origin. Relatively little is known about its occurrence in SARS CoV-2 infected COVID-19 patients. Herein, we report a case of SAT in a 58-year-old patient that was apparently triggered by infection with SARS CoV-2. Clinical, laboratory and imaging features of the patient are presented. The patient was vitally stable with a slightly tender and warm thyroid gland, which was painful on swallowing. His free thyroxine (FT4) was elevated, thyroid stimulating hormone (TSH) was below normal and free triiodothyronine (FT3) was in the physiological range. Previous thyroid exam conducted as a part of routine annual physical checkup was normal. The patient was put on prednisolone and recovered completely within three weeks.

Subacute thyroiditis in a patient with psoriatic arthritis switched from secukinumab to adalimumab: a case report and literature review.

A 71-year-old Japanese female with psoriatic arthritis (PsA) was admitted for fever and neck pain. Her medication had been switched from secukinumab, an interleukin (IL)-17A inhibitor, to adalimumab, a tumour necrosis factor (TNF)-α inhibitor, due to secondary failure for PsA. She was diagnosed with subacute thyroiditis (SAT) on the basis of thyroid hormone levels and thyroid ultrasound findings. Her SAT symptoms improved with prednisolone administration (15 mg/day). Following the administration of ixekizumab, an IL-17A inhibitor, her PsA improved without SAT relapse. SAT mechanism associated with TNF inhibitors remains unknown, but cytokine imbalance may be involved.

Subacute Thyroiditis After Sars-COV-2 Infection.

CONTEXT: Subacute thyroiditis (SAT) is a thyroid disease of viral or postviral origin. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that began in Wuhan, China, has spread rapidly worldwide and Italy has been severely affected by this outbreak. OBJECTIVES: The objective of this work is to report the first case of SAT related to SARS-CoV-2 infection. METHODS: We describe the clinical, laboratory, and imaging features of an 18-year-old woman who came to our attention for fever, neck pain radiated to the jaw, and palpitations occurring 15 days after a SARS-CoV-2-positive oropharyngeal swab. Coronavirus disease 2019 (COVID-19) had been mild and the patient had completely recovered in a few days. RESULTS: At physical examination the patient presented with a slightly increased heart rate and a painful and enlarged thyroid on palpation. At laboratory exams free thyroxine and free triiodothyronine were high, thyrotropin undetectable, and inflammatory markers and white blood cell count elevated. Bilateral and diffuse hypoechoic areas were detected at neck ultrasound. One month earlier, thyroid function and imaging both were normal. We diagnosed SAT and the patient started prednisone. Neck pain and fever recovered within 2 days and the remaining symptoms within 1 week. Thyroid function and inflammatory markers normalized in 40 days. CONCLUSIONS: We report the first case of SAT after a SARS-CoV-2 infection. We alert clinicians to additional and unreported clinical manifestations associated with COVID-19.

Establishing a diagnostic scale of subacute thyroiditis without radioisotope scanning.

BACKGROUND: Radioisotope scanning is important to diagnose subacute thyroiditis (SAT), but it's not always available. So we aim to establish a diagnostic scale for SAT without radioisotope scanning. METHODS: The suspected SAT patients hospitalized in Yuebei people's Hospital from January 2012 to December 2016 were selected and divided into study group and control group according to whether they were diagnosed as SAT. The clinical indexes of two groups were collected and the diagnostic scale of SAT was established by using binary logistic regression analysis. The effectiveness of the scale was evaluated by ROC curve. RESULTS: Of 309 patients, 58.25% of patients were confirmed with SAT and the remaining 41.75% of patients were not diagnosed with SAT. After univariate analysis, variables which were considered statistically different(P < 0. 05) between the two groups were selected as independent variables and the diagnosis of SAT was taken as dependent variable in the binary logistic regression model. The logistic regression model consisted of 4 variables, each was thyroid tenderness, firm on palpation, increased ESR and elevated thyroid hormone level. The P value of Omnibus tests was≤0. 001 and the Nagelkerke R Square was 0. 915. The diagnostic scoring scale was established with these four variables according to their regression coefficient. The area under the ROC curve for this diagnostic scale was 0. 991(95% confidence interval, 0. 982-0.999). The highest Youden index was 0. 912, the corresponding cut-off point was 7. Internally validation shows a sensitivity of 92. 78% and a specificity of 98.45% of our scale. CONCLUSIONS: We established and validated a diagnostic scale for SAT without the need for radioisotope scanning for the first time. It has good application in institutions that do not have radioisotope machines or among pregnant and lactating women.

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.

Time-Lag Between Symptom Onset and Diagnosis of Subacute Thyroiditis - How to Avoid the Delay of Diagnosis and Unnecessary Overuse of Antibiotics.

Clinical symptoms of subacute thyroiditis (SAT) may be misleading and the proper diagnosis is significantly delayed, and many unnecessary therapeutic methods are used, including application of antibiotics. The purpose of the study is to analyze the reasons and frequency of delayed SAT diagnosis and unnecessary antibiotic treatment and to propose a simple algorithm to facilitate the diagnosis and prevent antibiotic abuse. Sixty-four SAT patients were divided into groups depending on the period of time from the first symptoms of SAT to diagnosis and on the unnecessary use of antibiotics. Data from medical history and laboratory test results were analyzed for individual groups to determine the reasons for delayed diagnosis and incorrect treatment. In 73% of patients, the diagnosis was delayed from over two weeks up to six months. Among 62 patients who provided data on antibiotic use, 29 (46.77%) were treated with one or more antibiotics due to SAT symptoms. Fever, preceding infection, increased C-reactive protein (CRP), and WBC were characteristic for the antibiotic treated group. Fever, preceding infection, increased CRP and WBC are typical for both SAT and infection and are the main symptoms leading to misdiagnosis and unnecessary antibiotic treatment in SAT. Thus, in all patients with neck pain or other SAT-like symptoms, thorough clinical examination of the neck is mandatory. When firm and/or tender thyroid nodule/goitre is present and erythrocyte sedimentation rate /CRP is increased, patient should be promptly referred to an endocrinologist, and antibiotics are not recommended.

Neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, and platelet-tolymphocyte ratio in different etiological causes of thyrotoxicosis

Background/aim: The most common causes of thyrotoxicosis include Graves' disease (GD), toxic multinodular goiter (TMNG), toxic adenoma (TA), and subacute granulomatous thyroiditis (SAT). In our study, we aimed to see whether neutrophil­to­lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet­to­lymphocyte ratio (PLR), and mean platelet volume (MPV) may be helpful in the differential diagnosis of these diseases. Materials and methods: We retrospectively analyzed the hospital records of the Endocrinology Clinic of our hospital between 2016 and 2019. We included data from 66 GD, 37 TA, and 35 SAT patients. We compared the data with those of 35 healthy subjects as controls. Results: NLR, MLR, and PLR were found to be higher in the SAT group when compared to other groups. The post hoc analysis of comparison of NLR, MLR, and PLR in each group showed that NLR and PLR were significantly different in the SAT group when compared to the GD, TA, and controls groups (P < 0.001, P = 0.003, and P < 0.001 for NLR respectively and P < 0.001 for PLR in all groups). MPV levels were different between groups (P = 0.007). However, the intergroup analysis (Tukey's test) failed to show a statistically significant difference for any of the groups. In patients with SAT, PLR and NLR were significantly higher than in the GD, TA, and control groups. MLR was also higher in SAT when compared to other groups, but the difference was not statistically significant. Conclusion: High PLR and NLR may be helpful to differentiate SAT from GD and TA, the other common causes of thyrotoxicosis.

The Risk of Recurrence of Subacute Thyroiditis Is HLA-Dependent.

The frequency of recurrence of subacute thyroiditis (SAT) is rather high, reaching 20⁻30%. The reason for SAT relapse is still unknown. Recently, we have demonstrated the association between SAT and the presence of HLA-B*18:01, DRB1*01, and C*04:01, apart from the previously known HLA-B*35. The aim of the present study was to evaluate the correlation between SAT-associated HLA haplotypes and the risk of SAT recurrence. HLA-A, -B, -C, -DQB1 and -DRB1 were genotyped using a next-generation sequencing method in 49 SAT patients. The patients were divided into the following HLA groups: 1. HLA-B*35 and/or HLA-C*04, but without any other of the analyzed antigens; 2. HLA-DRB1*01, regardless of the co-presence of HLA-B*35 or -C*04:01, but without HLA-B*18:01; 3. HLA-B18 only, without any other antigen; 4. HLA-B*18:01 plus -B*35, regardless of the presence of any other analyzed antigens. The recurrence rate was compared between the groups. The recurrence rate was significantly increased in patients with HLA-B*18:01 plus HLA-B*35. In conclusion, the risk of SAT recurrence was HLA-dependent and the determining factor was the co-presence of HLA-B*18:01 and -B*35. In such high-risk patients, the steroid treatment regimen should be intensified with a slower dose reduction.

Clostridium difficile colitis in the setting of subacute thyroiditis: the chicken or the egg.

Subacutethyroiditis is a self-limited inflammatory condition commonly of viral aetiology, that manifests through phases of thyroid hormone changes over a 6-8 month period. A 24-year-old active duty military man, undergoing treatment for recurrent Clostridiumdifficile infection, presented for clinical evaluation and was found to have a thyroid stimulating hormone level of 0.003 mg/dL. Further labs revealed a normal T4, elevated T3 at 5.0 pg/mL and elevated C reactive protein at 3.69 mg/L. The patient was followed with monthly labs and the abnormal thyroid stimulating hormone and triiodothyronine levels resolved after the completion of his C. difficile treatment. While subacute thyroiditis has historically been due to viral causes, rarely do we see this condition associated with an intestinal bacterial source.

TNF-alpha is upregulated in subacute thyroiditis and stimulates expression of miR-155-5p in thyroid follicle cells.

Tumor necrosis factor alpha (TNF-α) regulates the expression of proinflammatory cytokines and apoptosis in thyroids. miR-155-5p is upregulated in circulating microvesicles in patients with autoimmune thyroiditis. However, the function and molecular mechanisms of TNF-α and miR-155-5p in the initiation and progression of subacute thyroiditis are largely unknown. Herein, we determined serum TNF-α levels in subacute thyroiditis patients and normal healthy controls by ELISA assay. Proliferation and apoptosis of rat thyroid follicle FRTL-5 cells were determined by MTT, TUNEL, and annexin V staining assays. Protein levels and phosphorylation status were assessed by immunoblotting. miR-155-5p expression was determined by the real-time quantitative PCR. Serum TNF-α was significantly upregulated in patients with subacute thyroiditis compared to that in normal healthy controls. In rat thyroid follicle FRTL-5 cells, TNF-α treatment led to a reduction of cell proliferation and an induction of apoptosis. It also increased IL-6 expression and phosphorylation of JAK2 and STAT3. Importantly, we demonstrated that serum miR-155-5p was upregulated in subacute thyroiditis patients and TNF-α stimulated the expression of miR-155-5p in FRTL-5 cells. We found that miR-155-5p inhibited the proliferation and induced apoptosis of FRTL-5 cells and increased the expression of IL-6 in FRTL-5 cells. Our results demonstrated that serum TNF-α and miR-155-5p were upregulated in patients with subacute thyroiditis, and TNF-α inhibited proliferation and induced apoptosis of rat thyroid follicle FRTL-5 cells via modulating the IL-6-JAK2/STAT3 pathway and miR-155-5p signaling. Our findings suggest that miR-155-5p might be a novel biomarker of subacute thyroiditis.

Asymptomatic thyroiditis presenting as pyrexia of unknown origin: a case report.

BACKGROUND: Pyrexia of unknown origin is a difficult and challenging problem for the physician. Endocrine disorders, such as subacute thyroiditis, rarely present with pyrexia of unknown origin. Subacute thyroiditis can have a broad spectrum of clinical presentations including fever and biochemical thyrotoxicosis without overt signs or symptoms. CASE PRESENTATION: A previously healthy 42-year-old Sri Lankan Sinhalese man was extensively investigated for a prolonged fever of 3 weeks with high inflammatory markers. He had mild tenderness over his neck with cervical lymphadenopathy with no thyrotoxic symptoms or signs. An ultrasound scan revealed an enlarged thyroid with increased vascularity and he had suppressed thyroid-stimulating hormone with elevated free thyroxine and free triiodothyronine hormone levels. Fine-needle aspiration cytology confirmed thyroiditis. He responded well to low-dose steroids. CONCLUSION: Subacute thyroiditis should be considered in the diagnostic workup of pyrexia of unknown origin even in the absence of overt toxic symptoms of thyroid hormone excess.

[Etanercept-induced subacute thyroiditis. Case report and literature review]. / Etanercept okozta szubakut pajzsmirigygyulladás.

65 years old male patient received 4 mg/day methylprednisolone baseline therapy and 50 mg/week etanercept treatment for 5 years due to rheumatoid arthritis. The patient experienced pain in neck, and developed weakness, fever and dysphagia. He had normal blood count but accelerated erythrocyte sedimentation rate (88 mm/hour), elevated CRP (49.3 mg/l) and hyperthyroidism (TSH 0.006 mIU/l, fT4 27.22 pmol/l, fT3 5.61 pmol/l). The autoimmune origin could be excluded because of normal values of antibodies against thyreoidea peroxidase and TSH receptor. The ultrasound investigation showed focal hypoechogenic structure and low vascularisation. Based on the laboratory and ultrasound results as well as clinical signs etanercept related subacute thyroiditis was supposed. As part of the treatment we interrupted the etanercept treatment and gave 16 mg methylprednisolone for 5 days, then 8 mg for 7 days, after that the patient received the daily 4 mg of methylprednisolone as baseline therapy. After rapid improvement the symptoms got worse again so we repeated the administration of methylprednisolone treatment with a higher dose (16 mg/day for 5 days then 8 mg/day for two months). Thyroid functions and the inflammatory markers got normalized. We conclude the necessity of monitoring the thyroid function during etanercept treatment thus avoiding this rare but serious side effect. Orv Hetil. 2017; 158(39): 1550-1554.

Mean Platelet Volume and Platelet Count are Elevated in Patients with Subacute Thyroiditis.

BACKGROUND: Platelet parameters have been studied in many diseases. This study explored the changes of mean platelet volume (MPV) and platelet count (PLT) in subacute thyroiditis (SAT). METHODS: We retrospectively studied 44 patients with SAT and 45 healthy individuals. Diagnosis was confirmed by pathologic examination of surgical specimens. RESULTS: There were no significant differences in age and gender between the SAT group and the control group. We compared the above indexes between the two groups. WBC and PLT were significantly higher and MPV was obviously lower in the SAT group. PLT had high sensitivity for diagnosis of SAT. CONCLUSIONS: PLT was elevated and MPV was decreased in SAT patients. A negative correlation between PLT and MPV was found.

Comparison of thyroglobulin and thyroid peroxidase antibodies measured by five different kits in autoimmune thyroid diseases.

It is generally believed that the detection of thyroid peroxidase antibodies (TPOAb) is superior to that of thyroglobulin antibodies (TgAb) for the diagnosis of Hashimoto's thyroiditis. However, limited data are available on the comparison of TgAb and TPOAb prevalence as a diagnostic measurement for Hashimoto's thyroiditis using sensitive immunoassays. We herein used five different current immunoassay kits (A-E) to compare the prevalence of TgAb and TPOAb in Hashimoto's thyroiditis (n = 70), Graves' disease (n = 70), painless thyroiditis (n = 50), and healthy control subjects (n = 100). In patients with Hashimoto's thyroiditis, positive TgAb was significantly more frequent than positive TPOAb in kits A-D (mean ± SD of the four kits: 98.6 ± 1.7 vs 81.4 ± 2.0%). In patients with Graves' disease, TgAb prevalence was almost equivalent to that of TPOAb in five kits. Patients with painless thyroiditis exhibited positive TgAb significantly more frequently than positive TPOAb in kits A-D (73.5 ± 4.1 vs 33.0 ± 3.4%). The prevalence of TgAb alone was significantly higher than that of TPOAb alone in both Hashimoto's thyroiditis and painless thyroiditis in kits A-D. In kit E, TgAb and TPOAb prevalence did not differ significantly for any disease, and TgAb distribution was different from other kits. In conclusion, the prevalence of TgAb was higher than that of TPOAb in patients with Hashimoto's thyroiditis and painless thyroiditis using commercially available kits. We suggest that TgAb immunoassay is the first choice of screening test for thyroid autoimmune abnormalities in Japan.