Urea Test
At a Glance
Why Get Tested?
To evaluate kidney function and monitor the effectiveness of dialysis
When to Get Tested?
If you have non-specific symptoms that may suggest a kidney problem or if you are suddenly ill or have a long term illness that may cause or be made worse by kidney disease
Sample Required?
A blood sample taken from a vein in the arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
Urea is produced when protein is broken down by the body. Nitrogen in the form of ammonia is produced in the liver when protein is broken down. The nitrogen combines with other chemicals in the liver to form the waste product urea. The urea is released into the bloodstream and carried to the kidneys where it is filtered out of the blood and excreted in the urine. Healthy kidneys remove more than 90% of the urea the body produces, so blood levels can show how well your kidneys are working.
Most diseases that affect the kidneys or liver can affect the amount of urea present in the blood. If increased amounts of urea are produced by the liver or decreased amounts are removed by the kidneys then blood urea concentrations will rise. If significant liver damage or disease reduces the production of urea then urea concentrations may fall.
How is the sample collected for testing?
A blood sample is taken from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is required.
The Test
How is it used?
Urea and creatinine levels are used to evaluate how well the kidney is working and to monitor patients with kidneys that are diseased or those receiving kidney dialysis.
When is it requested?
Urea may be used in a panel of tests:
- when someone has non-specific illness,
- as part of a routine group of tests, 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
Some symptoms and signs of kidney disfunction include:
- Tiredness, lack of concentration, poor appetitie, poor sleep
- Swelling or puffiness (oedema) around the eyes, writsts, ankles or tummy
- Urine that is foamy, blood strained or coffee-coloured
- A decrease in the amount of urine
- Problems urinating such as a burning sensation, abnormal discharge during urination or a change in the frequency of urination especially at night
- Mid-back pain below the ribs where the kidneys are located
- High blood pressure
What does the test result mean?
High urea levels suggest poor 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 levels are also seen in normal pregnancy.
Is there anything else I should know?
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 damage kidney function may increase urea levels. Your urea and creatinine may be monitored if you are on certain drugs.
Common Questions
Ask a Laboratory Scientist
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
