Urea Test
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
The urea test is a blood test in which a sample is taken from a vein to measure the amount of urea, a waste product formed from protein breakdown, in the bloodstream. It is used to assess kidney function and monitor kidney disease or dehydration, as abnormal levels may indicate impaired waste removal.
Why get tested?
To evaluate kidney function or to monitor the effectiveness of dialysis
When to get tested?
Urea is routinely measured as part of a “urea and electrolytes” (U&E) screen to assess kidney function. It may also be tested if you have symptoms of acute or chronic kidney disease.
Sample required?
A blood sample taken from a vein in the arm
Test preparation needed?
No test preparation is needed
Common questions
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.
Urea may alsonbe used in a panel of tests:
- when someone has non-specific illness,
- as part of a routine group of tests (often called “urea and electrolytes” (U&E),
- 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 dysfunction include:
- Tiredness, lack of concentration, poor appetite, poor sleep
- Swelling or puffiness (oedema) around the eyes, wrists, 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
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.
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 levels. Lower urea levels are also seen in infants and small children.
Drugs that can impair kidney function may increase urea levels. Your urea and creatinine may be monitored if you are on certain drugs.
Urea and creatinine are often the first tests that are used to check how well the kidneys are able to filter waste products from your blood. Your doctor may also request electrolyte tests such as sodium and potassium, or calcium to help understand how your kidneys are functioning.
Urea levels increase with age. Urea levels in very young babies are about 2/3 of the levels found in healthy young adults, while levels in adults over 60 years of age are slightly higher than younger adults. Levels are also slightly higher in men than women.
Urea levels are normally slightly lower in pregnancy, especially in the last few months. This is when the foetus is using large amounts of protein for growth and the blood volume of the mother increases, causing dilution of the urea in the blood.