What is the upper limit of sodium levels for hyponatremia?

The definition of hyponatremia is based on serum sodium levels being below the normal range. The normal sodium levels are typically considered to be between 135 mEq/L and 145 mEq/L. Therefore, the upper limit for normal sodium levels is 145 mEq/L. When sodium levels drop below 135 mEq/L, it is classified as hyponatremia.

The other choices listed do not define hyponatremia correctly, as levels above 145 mEq/L are not indicative of this condition. In critical care situations, understanding these thresholds is essential for recognizing and managing electrolyte imbalances effectively.