Biphasic periodic paralysis.

A young man with episodes characteristic of familial normokalemic periodic paralysis was restudied after a change in the nature of his attacks. He now has spontaneously occurring and provokable episodes of both hyperkalemic and hypokalemic periodic paralyses that are superimposed on a persistent myopathy. Hypokalemia seems to be associated with facilitated entry of glucose and potassium into muscles, whereas resistance to glucose and potassium entry accompanies hyperkalemia. The possibility that episodes of both hypokalemic and hyperkalemic weaknesses can occur in one person should be considered in pathogenic postulates regarding periodic paralysis.