Potassium is one of the most essential minerals in the body. In a healthy individual, approximately 90% of potassium is stored within cells, around 7.6% is stored in bones, about 1% is present in transcellular fluid, and only roughly 1.4% of potassium is found in the extracellular fluid. Potassium plays crucial physiological roles, including maintaining cellular metabolism, preserving the resting membrane potential of cells, regulating osmotic pressure between intracellular and extracellular compartments, and contributing to acid-base balance.
The body maintains potassium balance through the following mechanisms:
- Adjusting potassium distribution between intracellular and extracellular fluids via the Na+-K+ pump in the cellular membrane.
- Influencing potassium distribution through H+-K+ exchange between intracellular and extracellular compartments.
- Modulating potassium excretion by altering transmembrane potentials in renal tubular epithelial cells.
- Regulating renal potassium excretion through aldosterone and the distal tubule.
- Excreting potassium via sweat or through the colon.
The normal serum potassium concentration ranges from 3.5 to 5.5 mmol/L. Abnormal potassium metabolism can manifest as hypokalemia or hyperkalemia.
To be continued