Hyperkalaemic periodic paralysis: a rare presentation of Addison's disease.

A 44 year old man with longstanding diabetes mellitus gave a 6-month history of periodic attacks of flaccid quadriplegia. Following one of these episodes he was admitted for assessment. In view of persistent hyperkalaemia, hypoadrenalism was suspected and Addison's disease was confirmed biochemically. Adrenal replacement therapy restored the potassium levels to normal and resulted in no further attacks of paralysis.