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

OBJECTIVE: 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. METHODS: We discuss clinical presentation, diagnostic evaluation and subsequent management and follow-up in three patients. RESULTS: 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. CONCLUSION: 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.