A urea blood test measures the amount of urea nitrogen in your blood, a waste product produced by the liver during protein metabolism and removed by the kidneys. Elevated urea levels can indicate that the kidneys are not functioning properly, as they are responsible for filtering urea out of the bloodstream. Normal urea levels range from 7 to 20 mg/dL. High levels may signal kidney disease, dehydration, or excessive protein intake, while low levels might point to liver problems. Regular testing is crucial for assessing kidney function and ensuring overall health.