General Blood Test for Overall Health Screening and Evaluation of Common Symptoms, Including Fatigue, Infection, or Anemia
A laboratory test that measures the amount of urea nitrogen in fluid from the stomach, helping doctors evaluate certain digestive and metabolic conditions.
{"This test measures urea nitrogen levels in fluid extracted from the stomach","It helps doctors assess gastric function and detect abnormal connections between the digestive and urinary systems","The test involves passing a thin tube through the nose or mouth to collect stomach fluid","Results help diagnose conditions like gastric fistulas or evaluate protein metabolism","Follow your healthcare provider's specific instructions to prepare for this test"}
Key facts at a glance
- LOINC
- 14397-4
- Short code
- GFL UN
- Synonyms
- Urea nit Gast-mCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile container for gastric fluid collection
- Units
- not specified
- Ref low
- 10
- Ref high
- 50
- Critical range
- — – 100 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Enzymatic
- CPT
- 84484
- SNOMED
- 314214005
- Specimen volume
- Minimum 1-2 mL gastric fluid
- Stability
- Specimen should be processed within 2 hours of collection. If delay exceeds 2 hours, refrigerate at 2-8°C for up to 24 hours. Freeze at -20°C for longer storage.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
What is this test? This blood test checks components in your blood to help assess your overall health and look for signs of conditions such as anemia, infection, inflammation, or bleeding problems.
The Gastric Fluid Urea Nitrogen test measures the concentration of urea nitrogen in fluid collected from the stomach. Urea nitrogen is a waste product that is normally filtered from the blood by the kidneys and excreted in urine. When this test is performed on gastric fluid, it helps doctors understand how urea is being processed in your digestive system and whether there are any abnormal connections or conditions affecting the stomach and urinary system.
How is the test performed? A nurse or technician takes a small sample of your blood, usually from a vein in your arm, and sends it to a laboratory for testing.
A healthcare professional will insert a thin, flexible tube (nasogastric or orogastric tube) through your nose or mouth and into your stomach. This tube is used to collect a sample of gastric fluid. The procedure is typically quick and may cause some mild discomfort or gagging sensation. The collected fluid is then sent to a laboratory where the urea nitrogen concentration is measured using specialized equipment.
How to prepare for the test? For most blood tests, no special preparation is needed, but your provider may ask you to fast if additional tests are ordered, so follow the instructions you receive from your care team.
Your healthcare provider will give you specific instructions. Generally, you may need to fast (not eat or drink) for several hours before the test. Inform your doctor about all medications you are taking, as some medicines may affect the test results. Remove any dentures or dental appliances if instructed to do so.
Reference range
No established reference rangenot specified
Fasting required; collect via nasogastric tube or endoscopy per lab protocol
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
This test is primarily used to detect and evaluate abnormal connections (fistulas) between the stomach and the urinary system, such as gastro-ureteral or gastro-vesical fistulas. It may also be used to assess gastric secretions and evaluate protein metabolism. Additionally, the test can help distinguish between different types of digestive conditions and monitor certain treatments. The presence of urea nitrogen in gastric fluid at higher than expected levels may indicate that urine is entering the stomach, which is an abnormal finding requiring further investigation.
Frequently asked questions
Why is urea nitrogen measured in gastric fluid instead of blood?
Is the test painful?
How long does the test take?
What do abnormal results mean?
Are there any risks associated with this test?
Sources
- 1
- 2
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy