Sodium is the major extracellular cation in the body. It plays important roles in fluid balance, acid-base balance, glucose and amino acid absorption, and cell permeability. The total body sodium content is 4000 meq, with 50% in bones, 40% in extracellular fluid, and 10% in soft tissues. The daily sodium requirement is 5-10 g, though hypertensive patients should aim for 1 g. Common sodium sources include table salt, bread, vegetables, and dairy. Sodium levels are regulated by the kidneys, which filter and reabsorb most of the sodium from the glomerulus under control of aldosterone. Deviations from the normal serum sodium range of 135-145 meq/L can