In a patient with hypertonic hyponatremia, which laboratory value is most likely elevated?

In the context of hypertonic hyponatremia, the most relevant laboratory value that would be elevated is serum glucose. Hypertonic hyponatremia refers to a decrease in serum sodium concentration that occurs when there is a hypertonic substance present in the bloodstream, such as high levels of glucose or mannitol.

When blood glucose levels are significantly elevated, as seen in uncontrolled diabetes mellitus, the osmotic effect pulls water from the cells into the extracellular space, diluting serum sodium and leading to a falsely low measurement despite an overall high serum osmolarity. This situation highlights the need to differentiate between true hyponatremia (low serum sodium) and hypertonic hyponatremia, where sodium levels may be low due to the dilution effect of hyperglycemia.

Other options, such as serum potassium, serum sodium, and serum triglycerides, are not typically elevated in this specific condition. Serum potassium levels may remain stable or change based on other factors, while serum sodium is artificially low in this case due to the dilution effect, and serum triglycerides may not have a direct influence on sodium levels in the context of hypertonic hyponatremia. Thus, elevated serum glucose is the key