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Placental alkaline phosphatase (PLAP) in serum/plasma

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of placental alkaline phosphatase, an enzyme produced primarily by the placenta during pregnancy. It may also be present in other tissues and can sometimes be detected outside pregnancy.

Quick summary

["PLAP helps assess placental function and certain non-pregnancy-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
82902-8
Short code
GH 15M pre chal SerPl-aCnc
Synonyms
GH 15M pre chal SerPl-aCnc
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is Placental Alkaline Phosphatase Used For?

PLAP levels are often measured in pregnancy to monitor placental health, especially in cases of suspected placental insufficiency or complications like preeclampsia. It may also be used in non-pregnant individuals to evaluate conditions affecting liver, bone, or kidney function, though these uses are less common.

When Might You Need This Test?

A healthcare provider may order a PLAP test during pregnancy to check for placental issues or in rare cases of suspected metabolic disorders. Outside pregnancy, it might be used if you have symptoms like unexplained liver problems, bone pain, or certain cancers.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then sent to a lab for testing. The test measures the enzyme activity in your serum or plasma.

What Are Possible Results?

Results are typically reported as a ratio of enzyme activity (often compared to a reference range if available) or as a qualitative assessment of enzyme presence. Elevated levels may indicate placental issues in pregnancy or other conditions affecting organ function.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

PLAP (Serum/Plasma)

Frequently asked questions

Why might my PLAP levels be checked during pregnancy?
PLAP is often monitored in pregnancy to detect early signs of placental problems, such as reduced blood flow or placental dysfunction. Elevated levels may signal potential risks to the baby or mother, prompting further evaluation.
Can PLAP levels be elevated outside of pregnancy?
Yes, though less commonly. Elevated PLAP can occur in conditions affecting the liver, bones, or kidneys, or in certain cancers. Your doctor will consider your symptoms and overall health when interpreting results.
What could cause a low PLAP level?
Low PLAP levels in pregnancy may indicate placental insufficiency or other complications. Outside pregnancy, low levels are rare and may require further medical evaluation to determine underlying causes.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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 16, 2026. · Read our editorial policy