Acute transient hypokalaemia: new interpretation of a common event.

An investigation of 70 unselected hospital inpatients with a plasma potassium of 2.8 mmol/l or less showed that the group contained an excess of women and of the elderly. In nearly half the patients no attempt had been made to correct the hypokalaemia with potassium supplements. 26 of the patients had been recently admitted with an acute medical condition, including stroke and myocardial infarction. Those in this group whose plasma potassium was measured again showed that plasma potassium rose to near or within the normal range in about 4 days, whether or not oral potassium supplements were given. These results suggest that in many cases the hypokalaemia of acutely admitted medical patients, including patients after myocardial infarction, is a spontaneously reversible non-specific event. A likely explanation is that it is due to a transient shift of potassium into the cells.