Severe burns are listed as a hyponatremia cause via which mechanism?

• A. Severe burns
• B. Diabetic acidosis
• C. Salt losing nephropathy
• D. Pseudohyponatremia

Answer: (A)

Severe burns cause hyponatremia mainly through loss of sodium in burn wound exudate and damaged skin. When the skin barrier is destroyed, a large amount of salt and water leaks out with the wound fluid, and if replacement fluids don’t keep up, total body sodium falls relative to water, producing true hyponatremia. This is a salt-wasting, extracellular-volume–depleting process.

In contrast, hyponatremia from diabetic acidosis arises mainly from osmotic shifts due to high glucose pulling water into the extracellular space, not from loss of salt through the skin. Salt losing nephropathy involves renal sodium loss, not skin losses, and pseudohyponatremia is a laboratory artifact, not a real deficit of serum sodium.