Fluid and electrolyte problems in renal dysfunction

Nephrons are the structural and functional units of the kidneys. The nephrons affect changes to blood plasma via filtration, reabsorption, secretion and excretion. Through these mechanisms the kidneys maintain homeostasis of electrolyte concentrations, fluid volume, osmolality and acid-base balance. In addition to the work of the nephrons, the kidneys have further roles in calcium homeostasis and synthesize the hormones erythropoietin and renin. Acute injury and chronic failure of the kidneys can impact on the kidneys ability to maintain homeostasis and manage fluids and electrolyte balance effectively. This poses challenges to the anaesthetist, perioperative physician and the intensivist in maintaining homeostasis and preventing further injury or damage to the kidneys following surgical or medical stresses. Derangement of electrolytes can be fatal. Recognition and prompt treatment of these abnormalities are essential.