Potassium Disturbances

Physiologic BackgroundTop

Total body potassium content in an adult person weighing 70 kg is ~3500 mmol (~50 mmol/kg). A total of 90% of body potassium is intracellular.

The most important factors that determine blood potassium concentration are potassium intake, renal regulation of potassium excretion, and shifts of potassium between the extracellular and the intracellular compartments.

Daily dietary intake of potassium is typically from 20 to 100 mmol. Of the absorbed potassium, 90% is excreted in urine and 10% in stool. The percentage of potassium excreted in stool may increase to 30% to 40% in adults with chronic renal failure. Potassium is excreted into urine mainly by cells of the collecting ducts. Daily renal excretion of potassium in individuals with normal renal function may reach 300 to 400 mmol.