Subacute Thyroiditis May Occur After COVID-19, an Italian Case Study Finds

doctor inspecting young girl thyroid
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Researchers reported the first published case of an individual in Pisa, Italy, diagnosed with subacute thyroiditis after recovering from COVID-19.

Subacute thyroiditis may be a clinical manifestation associated with coronavirus disease 2019 (COVID-19), according to findings from a case study published in The Journal of Endocrinology & Metabolism.

Subacute thyroiditis is an inflammatory thyroid disease typically preceded by an upper respiratory tract infection and is believed to have viral or postviral origins. The incidence of subacute thyroiditis in individuals with COVID-19, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has not yet been characterized.

Researchers reported the first published case of an individual diagnosed with subacute thyroiditis after a COVID-19 diagnosis. A woman aged 18 years tested positive for SARS-CoV-2 from a swab collected on February 28, 2020, in Pisa, Italy. After mild upper respiratory symptoms including cough and rhinorrhea, the patient recovered completely after 4 days. Tests for SARS-CoV-2 on March 13 and March 14 returned negative results. The patient’s previous episode of isolated hyperthyrotropinemia on February 21 resulted in a thyroid evaluation, which showed normal thyroid function, insignificant levels of thyroglobulin antibodies (TgAb) and thyroperoxidase antibodies (TPOAb), and no abnormalities on ultrasound.

On March 17, the patient presented with sudden fever, fatigue, palpitations, and anterior neck pain radiating to the jaw. On March 19, the patient had an elevated heart rate of 90 beats per minute and palpation of the slightly tender and enlarged thyroid gland was markedly painful, but no respiratory symptoms were observed at this time. Blood tests showed that TPOAb levels were below the reference range (<10 U/mL), as were thyrotropin (TSH) receptor antibody (TRAb) levels (<1.5 U/mL). Tg was detectable at a low level (5.6 μg/L), free thyroxine (FT4) levels were elevated (27.2 nmol/L), and free triiodothyronine (FT3) levels were mildly elevated (8.7 pmol/L). TSH levels were undetectable (<0.04 mU/L) and TgAb levels were significantly elevated (120.2 U/mL). Erythrocyte sedimentation rate (90 mm/h), C-reactive protein (CRP) levels (6.9 mg/L), and white blood cell count (11,200 cells/L) were all elevated. In addition, a thyroid ultrasound showed multiple, diffuse hypoechoic areas. Given these results, the patient was diagnosed with subacute thyroiditis.

The patient began taking 25 mg/d of prednisone on March 20. Neck pain and fever dissipated after 2 days and the remaining symptoms dissipated within 1 week. On April 1, FT4, FT3, white blood cell count, and CRP levels were within the normal range; TSH had risen to near the normal range (0.2 mU/L); and erythrocyte sedimentation rate had declined to 28 mm/h. On April 27, all thyroid function tests and inflammatory markers were within the normal ranges after continued adherence to a tapered prednisone regimen.

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The study authors indicated that this case of subacute thyroiditis may have been related to SARS-CoV-2 infection. Although the use of glucocorticoids is contested in subacute thyroiditis, this case had a complete recovery of symptoms within 2 weeks of prednisone treatment, whereas the typical duration of thyroid dysfunction in these cases is approximately 3 months.

Clinicians “should be alerted about the possibility of this additional clinical manifestation related to SARS-CoV-2 infection,” concluded the authors of the case study.

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Brancatella A, Ricci D, Viola N, Sgrò D, Santini F, Latrofa F. Subacute thyroiditis after SARS-CoV-2 infection [published online May 21, 2020]. J Clin Endocrinol Metab. doi:10.1210/clinem/dgaa276