Urea is a waste product produced by the body when it breaks down proteins in the liver. Once the urea is made, it is transported to the kidneys, which filter it out of the blood and remove it from the body in the form of urine. Measuring the levels of urea in the blood can therefore reflect how well both the liver and the kidneys, are functioning. It is important to note that even if one kidney is severely damaged but the other is functioning perfectly, results may still return as normal.
What might a low result mean?
A low result may simply mean that you are overhydrated or are not consuming enough protein. Low levels of urea in the blood can also indicate liver disease which could prevent the body from making urea.
Low levels of urea can also be common in the blood of pregnant women.
What might a high result mean?
Elevated urea can simply mean that you are dehydrated but can also suggest the presence of a kidney disease. When the kidneys are not functioning adequately, they are unable to filter enough urea out of the blood and into the urine, leading to raised levels of urea in the blood. This can occur in chronic kidney disease.
Raised levels of urea can also arise if the kidneys are not supplied with sufficient blood. Conditions limiting kidney blood supply include gastrointestinal bleeds and congestive heart failure.