The serum osmolality of a patient with hyponatremia:
A) Will be similar to the urine osmolality
B) Should be greater than 300 mOsm
C) Should be lower than 275 mOsm
D) Will be falsely increased

Question

Quizplus · Accepted Answer

The serum osmolality of a patient with hyponatremia is expected to be lower than 275 mOsm because hyponatremia is defined as a serum sodium concentration less than 135 mEq/L, which is associated with a decreased serum osmolality. Choice A is incorrect because urine osmolality can vary in hyponatremic patients based on the cause of the hyponatremia. Choice B is incorrect because a serum osmolality greater than 300 mOsm would be suggestive of hypernatremia. Choice D is incorrect because there is no reason to suspect a falsely increased serum osmolality.

The Serum Osmolality of a Patient with Hyponatremia