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Alpisosserplimp

Published: July 31, 2026Updated: August 14, 2026

A blood test that measures different forms of alkaline phosphatase enzyme to help identify the source of elevated enzyme levels, typically to distinguish between liver and bone conditions.

Quick summary

{"Measures different forms (isoenzymes) of alkaline phosphatase in your blood","Helps doctors determine whether high ALP levels come from liver or bone","Useful for diagnosing liver diseases, bone disorders, or other conditions","A simple blood test performed in a laboratory","Results help guide proper treatment based on the underlying cause"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 14, 2026Editorial policy

Key facts at a glance

LOINC
14588-8
Short code
ALP ISO
Synonyms
ALP Isos SerPl-Imp
Category
chemistry
Sample
serum
Container
Serum separator tube (SST/gel tube) or red top plain tube
Units
not specified
Ref low
20
Ref high
140
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Electrophoresis or isoenzyme-specific assay (e.g., wheat germ lectin precipitation, heat inactivation, or neuraminidase treatment) to separate and identify ALP isoenzyme fractions
CPT
84080
SNOMED
396550006
Specimen volume
1.0-2.0 mL serum minimum
Stability
Room temperature: 2-3 days; Refrigerated (2-8°C): 5-7 days; Frozen (-20°C): several weeks. Avoid repeated freeze-thaw cycles.
Hemolysis max
50
Lipemia max
300
Icterus max
20
TAT
24–72 hours
Order
routine

What is this test?

The alkaline phosphatase isoenzymes test measures different forms (isoenzymes) of the alkaline phosphatase enzyme in your blood. Alkaline phosphatase (ALP) is an enzyme found in various tissues throughout your body, including the liver, bones, intestines, and kidneys. This test helps identify which specific organ or tissue is producing excess ALP when levels are elevated.

Why do I need this test?

Your doctor may order this test if a routine blood test shows that your total alkaline phosphatase level is higher than normal. Instead of just knowing that ALP is elevated, this test determines where the excess enzyme is coming from. This information helps your doctor distinguish between liver problems (such as hepatitis, gallstones, or cirrhosis) and bone disorders (such as Paget's disease, bone healing after fractures, or certain bone cancers).

How is the test performed?

A healthcare professional will draw a small blood sample from a vein in your arm using a needle. The blood sample is then sent to a laboratory for analysis. The test measures the different isoenzymes of alkaline phosphatase to determine their relative amounts and origins. You do not need to fast before this test unless your doctor specifically instructs you to do so.

What do the results mean?

The results show which type of alkaline phosphatase isoenzyme is predominant in your blood. High levels of liver isoenzymes suggest liver disease or gallbladder problems. High levels of bone isoenzymes suggest increased bone activity, which may occur in conditions like bone healing, Paget's disease, or certain bone disorders. Your doctor will interpret the results along with your other test results and clinical symptoms to make a diagnosis.

Reference range

Normal isoenzyme patternnot specified

Specimen: serum

Fasting preferred; fatty meals may elevate intestinal ALP fraction

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Is fasting required before the test?
Fasting is typically not required for the alkaline phosphatase isoenzymes test. However, follow any specific instructions your healthcare provider gives you. Some laboratories may recommend fasting if other tests are being performed at the same time.
What happens if my results are abnormal?
Abnormal results indicate that the elevated alkaline phosphatase is coming from a specific organ system. Your doctor will consider your symptoms, medical history, and other test results to determine the cause and appropriate treatment. Additional tests may be needed to confirm a diagnosis.
Can medications affect my test results?
Yes, certain medications can affect alkaline phosphatase levels. These include some antibiotics, anti-inflammatory drugs, cholesterol medications, and hormone treatments. Always inform your doctor about all medications and supplements you are taking before the test.
Is this test safe?
This test is very safe. The risks are minimal and include minor bruising, bleeding, or dizziness at the needle insertion site. These side effects typically resolve quickly.
How long does it take to get results?
Results are usually available within a few days, but the exact time may vary depending on the laboratory. Your healthcare provider will contact you with the results or discuss them at your follow-up appointment.
  1. 1
    MedlinePlus - Alkaline PhosphataseSource
  2. 2
    May Clinic - Alkaline PhosphataseSource
  3. 3
    ARUP Consult - Alkaline Phosphatase IsoenzymesSource

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.

Medical Disclaimer

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 14, 2026. · Read our editorial policy