A simple diagnosis of low serum sodium as hyponatremia is not sufficient to provide a treatment plan. Without testing for serum osmolality, urine osmolality, and urine sodium levels, we cannot know if the patient has true hyponatremia or “pseudo-hyponatremia”. Giving IV fluids to a patient without knowing the true diagnosis of hyponatremia through these lab results will not treat the low serum sodium and may extend the patient’s hospital stay by a day or more and compromise patient health.
The Value of Osmolality Testing in Nephrology and Emergency Medicine
Measured osmolality is a great initial screening tool when evaluating patients with metabolic acidosis, ingestions with various alcohols and alcohol-derivatives, common intoxications, and disorders of plasma sodium.