What is this test? The intestinal alkaline phosphatase (IAP) test measures the amount of a specific enzyme in your blood that comes from your small intestine. Alkaline phosphatase is found in many tissues throughout the body, but this test specifically looks at the intestinal variant known as ALP-2 or IAP, using a blood sample taken from a vein in your arm. Why is it important? Intestinal alkaline phosphatase helps protect the intestinal lining, supports fat absorption, regulates inflammation in the gut, and helps detoxify harmful substances made by bacteria. When the intestinal lining is damaged or inflamed, this enzyme can leak into the bloodstream in higher amounts, so measuring it helps your doctor assess your intestinal health. How is the test performed? A healthcare professional draws a small blood sample from a vein in your arm, and the sample is analyzed in a laboratory to measure the activity level of intestinal alkaline phosphatase. The procedure is quick and generally causes minimal discomfort. What do the results mean? Your healthcare provider interprets the results together with your overall health, symptoms, and other test findings. Elevated levels may indicate intestinal inflammation, damage to the intestinal lining, inflammatory bowel disease (IBD), celiac disease, or other conditions affecting the gut, and your doctor will explain what your specific results mean for your health. What can cause low intestinal alkaline phosphatase? Low levels are less common but may occur with certain nutritional deficiencies or some inherited conditions, and your doctor will interpret your results based on your complete medical history and other findings. How long does it take to get results? Results are usually available within a few days, depending on the laboratory, and your healthcare provider will contact you with the results or discuss them at your follow-up appointment. Are there any risks with this test? The risks are minimal and similar to any routine blood draw, possibly including slight bleeding, bruising, or infection at the puncture site, while serious complications are very rare.
This test measures the level of intestinal alkaline phosphatase enzyme in your blood, which helps assess intestinal health and function.
{"Intestinal alkaline phosphatase is an enzyme produced by the small intestine","It helps protect the gut lining and aids in nutrient absorption","Blood levels may increase with intestinal damage, inflammation, or certain diseases","The test is performed on a blood sample (serum or plasma)","Results help doctors evaluate digestive system health"}
Key facts at a glance
- LOINC
- 71365-1
- Short code
- ALP-I, Intestinal ALP
- Synonyms
- ALP Intest 2 SerPl-cCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red top tube
- Units
- not specified
- Ref low
- 0
- Ref high
- 10
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 18 years
- Method
- Spectrophotometry using p-nitrophenyl phosphate substrate
- CPT
- 84075
- SNOMED
- 271510006
- Specimen volume
- 1.0-2.0 mL of serum
- Stability
- Room temperature: 2-3 days; Refrigerated (2-8°C): 5-7 days; Frozen (-20°C): 30 days
- Hemolysis max
- 50
- Lipemia max
- 300
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The intestinal alkaline phosphatase (IAP) test measures the amount of a specific enzyme in your blood that comes from your small intestine. Alkaline phosphatase is found in various tissues throughout the body, but this test specifically looks at the intestinal variant (ALP-2 or IAP). The test is performed using a blood sample collected from a vein in your arm.
Why is it important?
Intestinal alkaline phosphatase plays several important roles in maintaining good health: It helps protect the intestinal lining, supports fat absorption, regulates inflammation in the gut, and helps detoxify harmful substances from bacteria. When the intestinal lining is damaged or inflamed, this enzyme can leak into the bloodstream in higher amounts, which is why measuring its levels can help doctors assess intestinal health.
How is the test performed?
A healthcare professional will draw a small blood sample from a vein in your arm. The sample is then sent to a laboratory where it is analyzed to measure the activity level of intestinal alkaline phosphatase. You do not need to fast before this test unless your doctor instructs otherwise. The procedure is quick and generally causes minimal discomfort.
What do the results mean?
Results are interpreted by your healthcare provider in the context of your overall health, symptoms, and other test results. Elevated levels of intestinal alkaline phosphatase may indicate intestinal inflammation, damage to the intestinal lining, inflammatory bowel disease (IBD), celiac disease, or other conditions affecting the gut. Your doctor will explain your specific results and what they mean for your health.
Reference range
0-10 U/Lnot specified
No special preparation required; high-fat meal may transiently elevate intestinal fraction
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated intestinal alkaline phosphatase levels in blood may indicate damage or inflammation in the intestinal lining. This can occur in conditions such as inflammatory bowel disease (Crohn's disease, ulcerative colitis), celiac disease, intestinal infections, or conditions causing malabsorption. The test may also be useful in monitoring gut health in patients with chronic digestive conditions. In some cases, it may be used alongside other liver and bone marker tests to help determine the source of elevated total alkaline phosphatase.
Frequently asked questions
Do I need to fast before this test?
Is this test painful?
What can cause low intestinal alkaline phosphatase?
How long does it take to get results?
Are there any risks 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 10, 2026. · Read our editorial policy