A core responsibility of the kidneys is to regulate the homeostasis of serum potassium. An adequate gradient of potassium across the cell membrane with a high potassium level in the cell and a much lower extracellular potassium content is needed to generate a balanced electrophysiology in order to enable excitability of cell membranes. This is particularly important for nerve and muscle function. A major disturbance of the serum potassium level can be very hazardous for the human organism, with cardiac arrhythmias as a primary consequence.
Therefore, when the kidneys fail to take control of the potassium balance due to chronically impaired tissue, an important reason to conduct dialysis therapy is to remove excess potassium.
In CKD patients, an increase of serum potassium levels is primarily counterbalanced by an upgrade of potassium within cells. But in CKD stage 5, the adaption capacity of cells is overstrained which leads to an increase in serum potassium. Acute medical problems in terms of disturbed heart rhythm may occur if the condition remains untreated.