Which laboratory finding is associated with dehydration?

In the context of dehydration, increased osmolality is a key laboratory finding. Osmolality refers to the concentration of solutes in blood serum, and when a person is dehydrated, there is a reduction in water volume relative to solutes, leading to an increase in serum osmolality. This occurs because the body loses more water than solutes, resulting in a higher concentration of solutes such as sodium and waste products in the bloodstream.

Dehydration typically causes the kidneys to conserve water, which may result in concentrated urine and fewer instances of urine output, contrasting with increased urine output. Additionally, in dehydration, sodium levels may actually increase due to the loss of fluid that makes the remaining sodium appear more concentrated, rather than decreasing. Lastly, blood urea nitrogen (BUN) levels often rise in dehydration due to relative increases in protein concentration and decreased renal perfusion, indicating the kidneys are not diluting urea appropriately due to low fluid levels. Thus, higher osmolality is a direct consequence of dehydration, making it the correct answer in this context.