What lab finding is associated with dehydration?

• A. Elevated BUN and creatinine
• B. Low cholesterol
• C. High potassium
• D. Decreased glucose

Answer: (A)

When the body is dehydrated, circulating volume drops and renal perfusion decreases. The kidneys respond by reabsorbing more urea to conserve water, while their filtration rate falls, so both BUN and creatinine rise in the blood. The pattern of BUN rising disproportionately compared with creatinine—often with a high BUN:creatinine ratio—points to prerenal azotemia from dehydration. That combination of elevated BUN and creatinine is a classic lab sign of dehydration. Other options aren’t as directly linked: cholesterol isn’t an acute marker of dehydration, potassium may be affected by other factors but isn’t reliably high simply from dehydration, and glucose levels aren’t a primary dehydration indicator.