History and admission findings: A 38-year-old previously healthy Swiss presented with acute onset of progressive weakness in his legs in the morning hours after a carbohydrate-rich meal the preceding evening. Examination on admission revealed symmetrical paresis affecting the upper and lower limbs without involvement of the respiratory muscles. Hyperthyroidism was suspected. Similar symptoms three weeks before admission had earlier resolved spontaneously.
Investigations: Laboratory tests revealed severe hypokalemia of 1.4 mmol/l. Hyperthyroidism, caused by Grave's disease, was confirmed and a diagnosis of hypokalemic thyrotoxic periodic paralysis (TPP) was made. TREATMENT AND FOLLOW-UP: After initiating potassium replacement paresis was observed to disappear within three hours. Symptomatic treatment with propranolol and thyrostatic treatment with carbimazole prevented further episodes of paresis.
Conclusion: Hypokalemic thyrotoxic periodic paresis is a rare but increasingly common medical condition among people living in Western Europe. Diagnostically one's attention should turn to TPP at the presentation of acute paresis in combination with hypokalemia, especially in young men. Serious cardio-pulmonary complications can be avoided with early diagnosis and treatment.