Urea and creatinine levels are used to evaluate kidney function and to monitor patients with kidney failure or those receiving dialysis.

Urea may be used in a panel of tests:

• when someone has non-specific illness,
• as part of a routine testing panel, or
• to check how the kidneys are functioning before starting to take certain drugs.

Urea is often requested with creatinine:

• if kidney problems are suspected,
• to monitor treatment of kidney disease, or
• to monitor kidney function while someone is on certain drugs.

High urea levels suggest impaired kidney function. This may be due to acute or chronic kidney disease. However, there are many things besides kidney disease that can affect urea levels such as decreased blood flow to the kidneys as in congestive heart failure, shock, stress, recent heart attack or severe burns; bleeding from the gastrointestinal tract; conditions that cause obstruction of urine flow; or dehydration.

Low urea levels are not common and are not usually a cause for concern. They can be seen in severe liver disease or malnutrition but are not used to diagnose or monitor these conditions. Low urea is also seen in normal pregnancy.

Urea levels increase with age and also with the amount of protein in your diet. High-protein diets may cause abnormally high urea levels. Very low-protein diets can cause abnormally low urea. Lower urea levels are also seen in infants and small children.

Drugs that impair kidney function may increase urea levels. Your urea and creatinine may be monitored if you are on certain drugs.