Disorders of Potassium Metabolism

Abstract

The concentration of potassium in our cells is some 37 times higher than in the extracellular compartment. Maintenance of this transcellular concentration gradient is central for normal cell function in general and for nerve conduction and muscle contraction in particular. Not surprisingly, multiple homeostatic mechanisms regulate the internal distribution of K⁺, as well as maintaining body K⁺ stores stable. Disorders of K⁺ metabolism occur when one or more of these systems is disrupted. Such disorders are often asymptomatic or only associated with mild and nonspecific symptoms. As a result, they are usually first detected, sometimes incidentally, by uncovering an abnormality in serum potassium concentration ([K⁺]). Although often asymptomatic, disorders of K⁺ metabolism can also produce life-threatening cardiac arrhythmias or paralyses with little or no warning. In such instances, the ability to recognize the problem and intervene in a timely fashion can be lifesaving. Management of disorders of K⁺ metabolism is based firmly on an understanding of normal K⁺ homeostasis. As a necessary introduction to these disorders, a brief review of normal K⁺ balance is presented below.