What is a common indicator that a patient may be dehydrated?

The presence of a BUN (Blood Urea Nitrogen) level of 28 is a common indicator that a patient may be dehydrated. In dehydration, there is a decrease in the volume of fluid in the body, which leads to a concentration of waste products, including urea. This elevated BUN level suggests that the kidneys are either retaining more urea due to decreased renal perfusion or that there is reduced fluid volume available to sufficiently dilute these waste products. Normally, BUN levels are used to assess kidney function and dietary protein intake; thus, an elevated level amidst dehydration signals that the kidneys are under stress or that the body's fluid status is insufficient.

In assessing hydration status, blood pressure can also be impacted; however, dehydration is more directly reflected in laboratory values like BUN rather than blood pressure alone. While elevated potassium levels and decreased white blood cell counts might indicate other medical conditions, they are not as directly associated with dehydration as an elevated BUN level is.