Urine Alkaline Phosphatase (ALP) Test
A urine test that measures the level of alkaline phosphatase, an enzyme that can indicate kidney or urinary tract health.
{"Alkaline phosphatase (ALP) is an enzyme found in kidneys, liver, and bones","Elevated urine ALP may indicate kidney damage or urinary tract issues","The test uses a simple urine sample collected during a routine urine test","Results help doctors diagnose and monitor kidney-related conditions","No special preparation is typically needed before the test"}
Key facts at a glance
- LOINC
- 1776-4
- Short code
- ALP U
- Synonyms
- ALP Ur-mCnc
- Category
- chemistry
- Sample
- urine
- Container
- Clean-catch urine container (sterile plastic or glass)
- Units
- not specified
- Ref low
- 0.5
- Ref high
- 12
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Enzymatic colorimetric assay (p-nitrophenyl phosphate substrate)
- CPT
- 82045
- SNOMED
- 269225004
- Specimen volume
- 10-50 mL preferred
- Stability
- Room temperature: 24 hours; Refrigerated (2-8°C): 72 hours; Frozen (-20°C): several weeks
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
The urine alkaline phosphatase (ALP) test measures the amount of this enzyme in your urine. Alkaline phosphatase is a protein that helps break down nutrients in your body and is normally found in tissues throughout the body, including the kidneys, liver, intestines, and bones. When kidney cells are damaged or when there is inflammation in the urinary tract, ALP can leak into urine. This test helps healthcare providers detect kidney damage or urinary tract problems that might not be visible otherwise.
How is the test performed?
The test is performed on a urine sample. You will be asked to collect a clean-catch midstream urine sample in a sterile container. This means you will urinate a small amount first, then collect the middle portion of your urine stream into the container. The sample is then sent to a laboratory where technicians measure the ALP concentration using special chemical analysis. The procedure is quick, painless, and similar to a routine urine analysis.
What do the results mean?
Normal urine ALP levels vary by laboratory, but generally, low to undetectable levels are considered normal. Elevated urine ALP levels may indicate: kidney damage from conditions like acute kidney injury or chronic kidney disease; urinary tract infections or inflammation; kidney stones; certain medications that affect kidney function; or rarely, certain types of cancer. Your healthcare provider will interpret your results alongside other tests and your overall health condition to make an accurate diagnosis.
Are there any risks or preparations needed?
There are no significant risks associated with this test beyond those of routine urine collection. Generally, no special preparation is required - you can eat and drink normally before the test. However, inform your healthcare provider about any medications, supplements, or vitamins you are taking, as some substances may affect test results. It is also helpful to tell your doctor about any existing kidney conditions or urinary tract problems you may have.
Reference range
Not established (lab-specific; typically low/undetectable)not specified
No special preparation required; random urine specimen
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The urine alkaline phosphatase test is clinically significant because it serves as an early indicator of renal (kidney) tubular damage. When kidney tubules are injured due to disease, infection, toxins, or medication side effects, ALP enzymes leak into the urine. This makes the test particularly valuable for: detecting acute kidney injury early; monitoring patients taking potentially kidney-toxic medications; distinguishing between different types of kidney disease; and evaluating urinary tract infections. The test is often used alongside other urine tests (like protein, blood, and other enzyme tests) and blood tests (like serum creatinine and BUN) to get a complete picture of kidney function.
Frequently asked questions
What is alkaline phosphatase and why is it in my urine?
What does a high urine ALP result mean?
Do I need to fast before this test?
How is this test different from a blood alkaline phosphatase test?
Will I need additional tests if my urine ALP 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 16, 2026. · Read our editorial policy