[A rare case of hypokalemic thyrotoxic periodic paralysis in a Caucasian patient with Basedow's disease].

Thyrotoxicosis periodic paralysis is a very rare complication of thyrotoxicosis in whites, but is more frequently reported in oriental and latin american populations and associates the clinical picture of hyperthyroidism with bouts of paralysis due to hypokalemia. The hypokalemia is due to a massive shift of potassium from the extra- to the intracellular compartment. In this paper the authors report a case of 34-years old white male with an history of hypokalemic periodic paralysis and hyperthyroidism, studied with potassium, thyroid hormone, TSH and thyroid antibodies sampling and thyroid ultrasonography with color-Doppler. The restoration of a euthyroid state with methimazole and propranolol was effective in preventing further episodes of paralysis. It is suggested that the mechanism for the development of the hypokalemic periodic paralysis is the intracellular blockade of potassium by the surplus of thyroid hormones.