Potassium Disorders: Evaluation and Management

Abstract

Potassium, the most abundant intracellular cation, plays a key role in vital cell functions. To ensure somatic growth, children maintain a positive potassium balance. Total body potassium content depends on both dietary intake and its excretion, primarily through the kidneys. The plasma concentration of potassium is a function of the total body potassium content and the internal potassium balance, determined by the relative distribution of potassium between the extracellular and intracellular fluid compartments. Insulin, catecholamines, and acid-base balance play a major role regulating the internal potassium balance. The renal handling of potassium is a complex process that involves filtration, reabsorption, and secretion. These processes are developmentally regulated; thus, the evaluation of children with disorders in potassium balance should always take into consideration the developmental stage of the patient. Hyperkalemia and hypokalemia are common and potentially life-threatening disorders. A careful history, including dietary intake, use of drugs with an effect on potassium metabolism, and evaluation of acid-base balance, is essential to establish an accurate diagnosis. In addition, identifying the cause requires a meticulous assessment of renal excretion of potassium, including estimation of GFR, evaluation of proximal tubular function, and the activity of mineralocorticoids in the distal nephron. The treatment should be aimed at correcting the primary cause, when possible. In symptomatic patients, the disturbances in plasma potassium concentration should be corrected promptly, with close monitoring of the electrocardiogram (ECG).