Hypermagnesemic periodic paralysis: treatment with digitalis and lithium carbonate.

An 18-year-old man suffering from a hereditary hyperkalemic periodic paralysis showed, in addition, a hypermagnesemic periodic paralysis with a 2.5-fold increase in serum magnesium level. All other serum electrolyte levels were normal. The hypermagnesemic periodic paralysis seems to have been caused by a disturbance of the renal tubular system. Thus, magnesium-stimulated paralysis was prevented by treatment with lithium carbonate and digitalis, which blocked the active ion transport.