Hypernatremia is most commonly caused by which condition?

Hypernatremia is most commonly caused by which condition?

• A. Dehydration
• B. Overhydration from IV fluids
• C. Hyperlipidemia
• D. Hypokalemia

Answer: (A)

Hypernatremia reflects a free-water deficit relative to sodium. The most common cause is dehydration—loss of water without adequate replacement. When water is lost or not ingested sufficiently, serum sodium rises and plasma osmolality increases. This is especially true in the elderly or hospitalized patients who may have limited access to fluids or increased insensible losses. Overhydration from IV fluids generally lowers sodium by diluting it (unless hypertonic solutions are used), so it isn’t the typical cause. Hyperlipidemia and hypokalemia don’t drive sodium balance in the way dehydration does.

Hypernatremia reflects a free-water deficit relative to sodium. The most common cause is dehydration—loss of water without adequate replacement. When water is lost or not ingested sufficiently, serum sodium rises and plasma osmolality increases. This is especially true in the elderly or hospitalized patients who may have limited access to fluids or increased insensible losses.

Overhydration from IV fluids generally lowers sodium by diluting it (unless hypertonic solutions are used), so it isn’t the typical cause. Hyperlipidemia and hypokalemia don’t drive sodium balance in the way dehydration does.