Since hyperthyroidism could be an acquired cause of hypokalemic periodic paralysis, thyroid function tests were performed, which revealed marked hyperthyroidism: TSH 0.015 uIU/L, fT4 60.5 pmol/L (upper normal value 22 pmol/L) and fT3 15.8 pmol/L (upper normal value 6.8 pmol/L), with positive anti-TSH receptor antibody (TRab) determination of 2.12 IU/L (upper normal value 1.75 IU/L) and thyroid peroxidase antibodies (ATPO) of 64 IU/mL (upper normal value 34 IU/mL). The gene discussed is TPO; the disease is hyperthyroidism.