Review of the pathophysiology of alterations in potassium homeostasis.

The 2 interrelated systems of external and internal balance that regulate potassium homeostasis must function properly if normal plasma potassium concentration and total body potassium content is to be maintained. Should external balance fail, with renal or gastrointestinal wasting of potassium, hypokalemia with depletion of total body potassium may result. In the absence of this type of potassium wasting, hypokalemia most often is caused by redistribution, with potassium moving from the extracellular-fluid into cells and total body potassium content remaining unaltered. Likewise, factors regulating internal balance may redistribute potassium from cells into the extracellular fluid and cause hyperkalemia, but with normal total body potassium content. Should the kidneys or urinary system fail to excrete potassium, hyperkalemia with an increase in total body potassium content would result.