Manifestations of thyroid disease post COVID-19 illness: Report of Hashimoto thyroiditis, Graves' disease, and...

We present three cases of thyroid dysfunction such as Hashimoto thyroiditis, Graves' disease and subacute thyroiditis which developed few weeks after resolution of acute phase of COVID -19 infection in patients with no prior thyroid disease.

We discuss clinical presentation, diagnostic evaluation and subsequent management and follow-up in three patients.

All three patients tested positive for COVID-19 infection prior to diagnosis. Patient 1. A 38-year-old female developed hypothyroidism 6 weeks after COVID-19 infection, confirmed by TSH 136 mIU/L (range 0.34-5.6), free T4 level 0.2 ng/dL (range 0.93-1.7). Patient 2. A 33-year-old female developed Graves' disease 8 weeks after COVID-19 infection, with a TSH <0.01 mIU/L (range 0.4-4.5), Free T4 2.1 ng/dl (range 0.8-1.8), total T3 216 ng/dl (range 76-181), elevated TSI 309 (normal <140). A 24-h thyroid uptake was calculated at 47.1% (normal values between 8% and 35). Patient responded favorably to methimazole 10 mg in few weeks. Patient 3. A 41-year old healthy female developed thyroiditis at 6 weeks after COVID-19 infection, with a TSH 0.01 mIU/L and free T4 1.9 ng/dL accompanied by low 24-h thyroid uptake, calculated at 0.09%. Three weeks later, she developed hypothyroidism, with a TSH 67.04 mIU/L and free T4 0.4 ng/dl.

The temporal relationship between COVID-19 infection in the patients described here raises the question of possible effects of COVID-19 on the immune system and the thyroid gland.