What is a Urea (24-hour Urine) test?
Urea (24-hour urine) measures the total amount of urea excreted in the urine over a complete 24-hour period.
Urea is a waste product formed in the liver when the body breaks down proteins. It is transported through the blood to the kidneys, where it is filtered and eliminated in urine.
Measuring urinary urea over 24 hours can provide information about protein metabolism, dietary protein intake, and kidney handling of urea.
What is it used for?
A 24-hour urine urea test may be used to:
Assess urea excretion by the kidneys
Evaluate protein metabolism
Estimate dietary protein intake in selected clinical situations
Help assess nitrogen balance
Support evaluation of kidney function in specific circumstances
Contribute to calculations used in nutritional assessment, particularly in patients with kidney disease
Why do I need a Urea (24-hour Urine) test?
Your healthcare provider may request this test if they need to:
Evaluate protein metabolism
Assess nutritional status or protein intake
Investigate abnormal blood urea results
Evaluate kidney function together with other tests
Estimate nitrogen balance, especially in hospitalized or critically ill patients
Assess protein losses and metabolism in certain kidney disorders
What happens during the test?
You will collect all urine produced during a 24-hour period in a special container.
A typical collection is:
In the morning, empty your bladder into the toilet and do not collect this first urine. Record the time.
Collect every urine specimen passed during the following 24 hours.
Store the container according to your laboratory's instructions, usually refrigerated.
At exactly 24 hours, empty your bladder and include this final urine specimen.
Return the completed collection to the laboratory.
It is very important not to miss any urine during the collection period.
Will I need to do anything to prepare for the test?
Usually, no fasting is required.
Your healthcare provider may ask you to maintain your usual diet and fluid intake during the collection period.
Because urinary urea is strongly influenced by protein intake, unusually high or low protein consumption can affect the result. Follow your healthcare provider's instructions rather than deliberately changing your diet before the test.
Tell your healthcare provider about any medications, supplements, or special diets you are following.
Are there any risks to the test?
There are no significant medical risks associated with collecting urine.
The main concern is an incomplete or incorrectly timed 24-hour collection, which can lead to an inaccurate result.
What do the results mean?
The result represents the total amount of urea nitrogen or urea eliminated in 24 hours, depending on the laboratory's reporting method.
Interpretation depends on:
Protein intake
Body size and muscle metabolism
Kidney function
Hydration
Liver function
Degree of tissue breakdown or catabolism
The completeness of the urine collection
Increased urinary urea
A high 24-hour urinary urea excretion may occur with:
High dietary protein intake
Increased protein breakdown (catabolism)
Certain conditions associated with increased tissue breakdown
Recovery from some catabolic states
A high result does not necessarily indicate kidney disease.
Decreased urinary urea
A low result may occur with:
Low protein intake
Malnutrition
Reduced protein metabolism
Severe liver dysfunction
Reduced urea production
Reduced kidney filtration or decreased urine output in some circumstances
Incomplete urine collection
Important note
Urinary urea is highly influenced by protein intake and metabolic status, so it should not be interpreted alone as a measure of kidney function.
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