Review articleNeurologic Manifestations of Electrolyte Disturbances
Section snippets
Sodium
Extracellular fluid volume is dependent on total body sodium, the principal osmotic component of that fluid compartment. Generally, patients with hyponatremia are hypo-osmolar, and patients with hypernatremia are hyperosmolar. The neurologic manifestations of hyponatremia and hypernatremia usually involve the central nervous system (CNS) rather than the peripheral nervous system and reflect hypo-osmolarity and hyperosmolarity, respectively. Because the brain has a limited capacity to adapt to
Potassium
Unlike sodium, the neurologic manifestations of potassium disturbances rarely involve the CNS. Approximately 98% of total body potassium is located intracellularly. Sixty percent of intracellular potassium is within skeletal muscle, which may explain the predominance of muscular symptoms in disorders producing hypokalemia and hyperkalemia.
Calcium
Plasma calcium stabilizes excitable membranes in muscle and nervous tissue. Disorders of calcium would therefore be expected to produce neurologic manifestations. The coordinated interactions of parathyroid hormone, cholecalciferol, and, probably, calcitonin regulate intestinal calcium absorption, renal calcium reabsorption, and bone resorption to closely control plasma calcium concentration.10
Magnesium
Less than 2% of total body magnesium is located within the extracellular fluid compartment. Although magnesium has an intracellular-extracellular distribution similar to that of potassium, most of the intracellular magnesium is bound and not exchangeable with the extracellular fluid. In fact, intracellular free magnesium is rigidly regulated despite wide variations in extracellular magnesium concentrations. Intracellular magnesium within the brain is also relatively stable.35 The teleological
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