Thyrotoxic hypokalemic periodic paralysis and COVID-19 infection

Various conditions causing weakness associated with coronavirus disease 2019 (COVID-19) infection have been described, including cerebrovascular diseases, acute myelitis, Guillain-Barre syndrome, myasthenia gravis, critical illness myopathy and neuropathy, myositis, and rhabdomyolysis. We report an adult man presenting with an unusual etiology of weakness after a COVID-19 infection. Thyrotoxic hypokalemic periodic paralysis (THPP) was diagnosed from the presence of Graves' disease and hypokalemia because of intra-cellular potassium shifting. His weakness and hypokalemia responded well to potassium supplements and a non-selective b-blocker, whereas his thyrotoxicosis was initially controlled by an anti-thyroid medication and subsequently with radioactive iodine therapy. He was also treated as having mild COVID-19 based on his normal chest X-ray and oxygenation level. This is the first report showing an association between COVID-19 infection and a paralysis attack of THPP. Physicians should be alerted about this unusual cause of weakness, particularly in Asian patients.