Potassium

• Potassium is the major intracellular cation.

• The K⁺ intake of individuals on an average Western diet is approximately 1 mEq/kg/d, 90% of which is absorbed by the GI tract. Maintenance of the steady state necessitates matching K⁺ excretion with ingestion.

• The elimination of potassium occurs predominately through renal excretion. It is highly dependent on the distal urine flow rate and aldosterone, both of which enhance Na reabsorption in exchange for K+ secretion in the distal nephron.