Purpose Subacute thyroiditis (SAT) is an inflammatory thyroid disorder of viral origin, generally preceded by an upper respiratory tract infection. Since the disorder is self-limiting, it is frequently underdiagnosed. However, the disease should not be overlooked since the associated thyrotoxicosis may worsen the clinical course of concomitant disorders (e.g., respiratory distress) and long-term sequelae, such as autoimmune hypothyroidism, have been reported. Methods Here we describe a woman who developed SAT with thyrotoxicosis after SARS-COV-2 infection. Coronavirus disease (COVID-19) symptoms were mild and the patient was managed with no specific treatment and recovered rapidly. Results Six weeks after the onset of the upper respiratory tract infection, the patient developed pain and tenderness in the anterior cervical region, fatigue, tremors, and palpitations. Physical examination revealed mild tremors of the extremities, a diffuse and painful goiter, and enlarged and tender cervical and submandibular lymph nodes. At biochemical evaluation, TSH was suppressed, FT3 and FT4 were high, and serum thyroglobulin was markedly increased (188 pg/mL; n.v. 0–40). Thyroid scintigraphy showed markedly reduced 99m Tc-perthecnetate uptake in the gland. All findings were consistent with SAT, and treatment with oral prednisone (25 mg/day as the starting dose, gradually tapered) was started. Under the corticosteroid therapy, there was progressive resolution of symptoms and signs, and, within 4 weeks, all thyroid functional tests and inflammatory indexes normalized. Conclusion Clinicians should be aware of thyroid manifestations potentially associated with COVID-19.

Introduction : During the COVID-19 pandemic thyroid gland alteration/dysfunction has been emerged as a possible endocrine complication. The present review is focused on inflammatory and autoimmune thyroid complications triggered by SARS-CoV-2 infection by searching through databases like MEDLINE and Scopus up to April 2021. Areas covered : Beside the occurrence of ‘non-thyroidal illness’ in severe clinical conditions, alterations of thyroid function and structure may occur during COVID-19 as a consequence of either direct or indirect effects of SARS-CoV-2 infection on the gland. On the one hand, SARS-CoV-2 uses ACE2 as a receptor to infect the host cells and ACE2 is highly expressed by follicular thyroid cells. On the other hand, COVID-19 is associated with a systemic inflammatory and immune response, involving Th1/Th17/Th2 lymphocytes and proinflammatory cytokines, which resembles the immune activation that occurs in immune-mediated thyroid diseases. COVID-19-related thyroid disorders include destructive thyroiditis and onset or relapse of autoimmune thyroid disorders, leading to a broad spectrum of thyroid dysfunction ranging from thyrotoxicosis to hypothyroidism, that may worsen COVID-19 clinical course and affect prognosis. Expert opinion : Physicians should be aware of the possible occurrence of thyroid dysfunction during and after SARS-CoV-2 infection. Further longitudinal studies are warranted to evaluate potential long-term sequelae.

The use of MIBI scintigraphy using quantitative analysis in the workup of cold nodules with indeterminate cytology is suggested in order to stratify patient risk for a malignant lesion better, thus reducing the number of patients referred to surgery. Surgical treatment should be planned in those patients with a WOind up to -19%.

Our data show for the first time that a location of a thyroid cancer in the isthmus is an additional risk factor for RAI avid metastatic disease in pT1a-pT1b DTC patients, regardless of the presence or absence of other risk factors.

Quantitative 99mTc-MIBI thyroid scintigraphy is a useful tool in differentiating malignant from benign thyroid nodules with indeterminate cytology. The aim of our report is to compare the diagnostic performance of different quantitative methods. We prospectively evaluated 20 patients affected by a thyroid nodule with a cytological diagnosis of class III or IV according to the Bethesda system. Planar images of the thyroid were acquired 10 and 60 minutes after 99mTc-MIBI administration and two different quantitative methods applied (i.e. wash-out index, WOind; retention index, R.I.). All patients underwent lobectomy or thyroidectomy and final histological findings were matched with MIBI results obtained with both quantitative methods. Four out of 20 patients had a final histological result of differentiated thyroid cancer, while benign findings were found in the remaining cases. Overall sensitivity, specificity, accuracy, PPV and NPV were 100% in all for the WOind and 100%, 57.1%, 62.5%, 25% for the R.I., respectively. In conclusion 99mTc-semiquantitative MIBI thyroid scintigraphy with WOind calculation is highly accurate in differential diagnosis of nodules with indeterminate cytology reading.