[Primary hypokalemic periodic paralysis. Presentation of 18 cases].

The clinical features of 16 males and 2 females with hypokalemic periodic paralysis (HPP) are presented. Five patients had familial HPP, 4 thyrotoxic HPP and 9 sporadic disease. The age of onset ranged from 6 to 42 years. Clinical pictures varied from paraparesis to severe quadriplegia. The disease onset was earlier in familial HPP (p < 0.05) while sporadic cases showed the most severe, albeit shorter paralysis (p < 0.05). On admission, serum potassium levels ranged from 1.5 to 3.3 mEq/L; they did not correlate with the severity of paralysis. Glucose-insulin provocation test was positive in 5/5 patients. Oral potassium chloride and amiloride were useful to prevent paralysis. Contrasting with reports from USA and Europe, in México, HPP is not exceptional, and should be considered in the differential diagnosis of acute paralysis.