Which laboratory finding is indicative of dehydration?

The finding that indicates dehydration is elevated osmolality. Osmolality refers to the concentration of solutes in the blood. When a person is dehydrated, the volume of fluid in the blood decreases, leading to a higher concentration of solutes, including sodium and other electrolytes. This increase in osmolality can be detected through laboratory tests and is a key indicator of the body's state of hydration.

In situations of dehydration, the body conserves water and results in a higher osmolality due to the relative increase in solute concentration. This can reflect a variety of conditions but is fundamentally connected to reduced fluid intake or increased fluid loss.

In contrast, decreased blood urea nitrogen (BUN) levels would not indicate dehydration; BUN levels can be altered by factors such as liver function and protein intake, rather than solely by hydration status. Increased carbon dioxide may reflect metabolic or respiratory conditions but does not directly correlate with dehydration. Lowered electrolytes typically occur in conditions where there is excess fluid, leading to dilution rather than dehydration. Understanding these relationships is vital for accurately assessing and managing patient hydration states.