Potassium homeostasis in renal failure

The critical importance of serum potassium concentration in both health and disease has been demonstrated more than a century ago when it was shown that rapid i.v. injection of potassium salts caused toxic and even fatal effects on the heart of the experimental animal [1]. The role played by potassium in the excitability of both nerve and muscle cells is now well established.Maintenance of a normal serum potassium concentration depends to a large extent on renal function, as more than 80% of the ingested potassium is excreted in the urine. Surprisingly, however, serum potassium level is kept within or slightly above normal limits during most of the progressive course of renal failure. Maintenance of potassium equilibrium despite a falling glomerular filtration reflects a progressive adaptation of the mechanisms regulating serum potassium concentration.In the present paper we shall review the different factors involved in the defense of potassium homeostasis in renal failure: the adaptation of renal excretory mechanisms, the role of gastrointestinal excretion, the cellular tolerance to potassium load, the resulting changes in potassium balance, and finally, the complications which might alter potassium homeostasis in renal failure