Placental Alkaline Phosphatase (PLAP) Test
A blood test that measures the amount of placental alkaline phosphatase in your blood. This enzyme is made by the placenta, the organ that forms during pregnancy to nourish and support your growing baby throughout pregnancy.
{"PLAP is a special enzyme made by the placenta to support pregnancy","The test helps monitor pregnancy health and detect potential complications","It may also be used to evaluate certain tumors in rare cases","A simple blood draw is all that's needed for this test","Results are compared to normal ranges for each stage of pregnancy"}
Key facts at a glance
- LOINC
- 71367-7
- Short code
- PLAP
- Synonyms
- ALP Plac 2 SerPl-cCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red top tube
- Units
- not specified
- Ref low
- 0
- Ref high
- 1
- Critical range
- — – 200 not specified
- Fasting
- false
- Population
- adult
- Sex
- female
- Age range
- 18–55 years
- Method
- Enzymatic colorimetric assay using para-nitrophenylphosphate (pNPP) substrate
- CPT
- 82040
- SNOMED
- 271588004
- Specimen volume
- 1-2 mL serum minimum
- Stability
- Room temperature: 8 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C): 30 days
- Hemolysis max
- 50
- Lipemia max
- 100
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The placental alkaline phosphatase (PLAP) test measures the amount of a specific enzyme in your blood. This enzyme is produced by the placenta, the organ that develops in your uterus during pregnancy to nourish your growing baby. PLAP first appears in the blood around 10-12 weeks of pregnancy and increases as the pregnancy progresses.
Why is it important?
PLAP serves important functions during pregnancy. It helps support the exchange of nutrients and waste products between you and your baby. By measuring PLAP levels, healthcare providers can get valuable information about how well the placenta is working. Abnormal levels may indicate problems with placental function or other pregnancy complications.
How is the test performed?
The test is simple and similar to other routine blood tests. A healthcare professional will draw a small sample of blood from your arm using a needle. The sample is then sent to a laboratory for analysis. No special preparation is typically needed, though your doctor may ask you to fast for a short time before the test.
Reference range
0-1 U/Lnot specified
No fasting or special preparation required
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
PLAP testing is primarily used to assess placental function and pregnancy health. Abnormally low PLAP levels may suggest placental insufficiency, which can lead to complications like intrauterine growth restriction (IUGR) or preeclampsia. Abnormally high levels may indicate conditions such as placental abruption, gestational diabetes, or in rare cases, certain tumors including ovarian or testicular cancers. The test is often used in combination with other prenatal tests to get a complete picture of pregnancy health.
Frequently asked questions
Is the PLAP test safe during pregnancy?
What do abnormal PLAP results mean?
How often is this test done during pregnancy?
Can PLAP levels predict baby complications?
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