2. This test measures the amount of placental alkaline phosphatase (PLAP), a specific protein, in your cerebrospinal fluid (CSF), which is the clear fluid that surrounds and protects your brain and spinal cord. Doctors may use the results to help identify or monitor certain conditions affecting the brain or nervous system.
This test measures the amount of placental alkaline phosphatase (PLAP), a specific protein, in your cerebrospinal fluid (CSF), which is the clear fluid that surrounds and protects your brain and spinal cord. Doctors may use the results to help identify or monitor certain conditions affecting the brain or nervous system.
{"PLAP is a protein normally produced during pregnancy","Elevated PLAP in CSF may indicate certain types of tumors","The test requires a lumbar puncture to collect CSF","Results help doctors diagnose and monitor specific conditions","Your healthcare provider will interpret your results"}
Key facts at a glance
- LOINC
- 59188-3
- Short code
- ALP placental CSF
- Synonyms
- ALP Plac CSF-cCnc
- Category
- chemistry
- Sample
- csf
- Container
- Sterile CSF collection tube (plain plastic or glass tube, no anticoagulant)
- Units
- not specified
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Enzymatic colorimetric assay (p-nitrophenyl phosphate substrate)
- CPT
- 82150
- SNOMED
- 314512003
- Specimen volume
- 1-2 mL CSF minimum, preferably 2-4 mL
- Stability
- Analyze within 2 hours of collection. If delay >2 hours, refrigerate at 2-8°C; analyze within 24 hours. Avoid repeated freezing/thawing.
- Hemolysis max
- 200
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The cerebrospinal fluid placental alkaline phosphatase (CSF PLAP) test measures the amount of a specific protein called placental alkaline phosphatase in the fluid that surrounds your brain and spinal cord. Placental alkaline phosphatase (PLAP) is normally produced by the placenta during pregnancy and is typically not found in measurable amounts in adults outside of pregnancy.
How is the sample collected?
This test requires a procedure called a lumbar puncture (spinal tap). During this procedure, a healthcare provider inserts a thin needle between the bones in your lower spine to collect a small amount of cerebrospinal fluid. The sample is then sent to a laboratory for analysis.
Why might I need this test?
Your doctor may order this test if they suspect certain medical conditions. PLAP can sometimes be produced by abnormal cells, so elevated levels in CSF may help doctors identify and monitor specific types of conditions, particularly those affecting the brain or nervous system.
Reference range
0-1 U/Lnot specified
No special preparation required; CSF obtained by lumbar puncture
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated levels of placental alkaline phosphatase in cerebrospinal fluid may be associated with certain types of tumors, particularly germ cell tumors that may involve the brain or central nervous system. This test can help doctors in diagnosing these conditions and may also be used to monitor how well treatment is working. However, test results must be interpreted by your healthcare provider in combination with other clinical findings, as other conditions can sometimes affect the results.
Frequently asked questions
Is this test painful?
How long does it take to get results?
What do high levels mean?
Are there any risks from the lumbar puncture?
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