Alkaline Phosphatase Test on Peritoneal Fluid (Ascites Fluid Analysis)
This test measures the amount of alkaline phosphatase enzyme in peritoneal fluid, the fluid found inside your abdomen, to help your doctor diagnose conditions affecting the lining of the abdominal cavity.
{"Alkaline phosphatase is an enzyme found in various tissues including liver, bone, and intestines","Elevated levels in peritoneal fluid may indicate liver disease, infection, or malignancy","The test helps differentiate between transudate and exudate types of abdominal fluid accumulation","Results are interpreted alongside other fluid analysis tests","Your healthcare provider will explain what your specific results mean for your condition"}
Key facts at a glance
- LOINC
- 40410-3
- Short code
- ALP PF
- Synonyms
- ALP Prt-cCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile polypropylene specimen container for fluid collection, red-top or gold-top serum separator tube if serum sample collected concurrently
- Units
- not specified
- Ref low
- 25
- Ref high
- 150
- Critical range
- — – 300 not specified
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Spectrophotometric enzymatic assay using para-nitrophenylphosphate (pNPP) substrate at 405 nm wavelength, following International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) recommendations
- CPT
- 84075
- SNOMED
- 271568005
- Specimen volume
- 1-2 mL of peritoneal fluid minimum; 3-5 mL preferred for complete analysis
- Stability
- Analyze within 2-4 hours of collection. If delay exceeds 4 hours, store at 2-8°C and analyze within 24 hours. Do not freeze peritoneal fluid samples.
- Hemolysis max
- 0
- Lipemia max
- 50
- Icterus max
- 40
- TAT
- 2–24 hours
- Order
- routine
What is this test?
The alkaline phosphatase test measures the amount of the enzyme alkaline phosphatase in peritoneal fluid, which is the fluid that lines the abdomen and surrounds the abdominal organs. This fluid is often called ascites fluid when it accumulates in excess amounts in the abdominal cavity.
Why is it performed?
This test is performed when a patient has fluid buildup in the abdomen (ascites). It helps doctors determine the cause of the fluid accumulation by distinguishing between different types of fluid. Alkaline phosphatase levels can indicate whether the fluid is due to increased pressure in the liver (transudate) or from inflammation, infection, or cancer (exudate).
How is the sample collected?
Peritoneal fluid is collected through a procedure called paracentesis. During this procedure, a healthcare provider inserts a thin needle through the abdominal wall to withdraw fluid from the abdominal cavity. The area is first cleaned and numbed with local anesthetic to minimize discomfort.
What do the results mean?
Elevated alkaline phosphatase in peritoneal fluid typically suggests that the fluid is an exudate, which may be caused by infection, inflammation, pancreatitis, or cancer. Normal or mildly elevated levels are more commonly associated with transudates, which are usually due to conditions like heart failure, liver cirrhosis, or kidney disease. Your doctor will interpret these results along with other tests to determine the underlying cause.
Reference range
None establishednot specified
No special preparation required; specimen obtained by paracentesis
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Alkaline phosphatase testing in peritoneal fluid helps differentiate between transudates and exudates. Elevated levels suggest exudative processes such as peritoneal infection (peritonitis), malignant ascites, pancreatitis, or tuberculosis. This information is crucial for guiding further diagnostic workup and treatment decisions. The test is often performed alongside other fluid analyses including protein, glucose, cell count, and culture to provide a comprehensive assessment of the ascites.
Frequently asked questions
Is the test painful?
How long does it take to get results?
Are there any risks from the paracentesis procedure?
Do I need to fast before this test?
What happens if my alkaline phosphatase is elevated?
Sources
- 1
- 2
- 3
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 10, 2026. · Read our editorial policy