Familial hyperkalemic periodic paralysis and bipolar disorder: a linkage and treatment study.

Familial hyperkalemic periodic paralysis and bipolar disorder are both hereditary disorders, characterized by episodes of illness separated by periods of remission, and possibly related to abnormalities in cellular ion transport. Recently we discovered a patient who suffered from both illnesses, as did his mother and grandmother. However, a detailed investigation of the pedigree suggested that these two disorders are not linked genetically. Furthermore, a placebo-controlled double-blind trial of lithium carbonate in this patient found lithium ineffective in preventing the attacks of paralysis, in contrast to another recent study which found lithium effective in hypermagnesemic periodic paralysis.