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Placental alkaline phosphatase (PLAC) 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 can help assess fetal well-being or detect certain placental or fetal conditions.

Quick summary

["PLAC levels may indicate placental health or potential complications during pregnancy."]

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

Key facts at a glance

LOINC
47767-9
Short code
GH sp2 p chal SerPl-aCnc
Synonyms
GH sp2 p 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

Why Is This Test Done?

Your healthcare provider may order this test to monitor fetal development, check for signs of placental issues (such as placental insufficiency or preeclampsia), or evaluate conditions like gestational diabetes or intrauterine growth restriction. It may also be used in prenatal screening or during labor to assess placental function.

What Does a Result Mean?

Results can vary based on pregnancy stage and individual health. Elevated levels might suggest placental abnormalities, while lower levels could indicate potential complications. Always discuss your results with your provider.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The sample is then sent to a lab for analysis using a specialized immunoassay or similar method to measure the enzyme concentration.

What Are Possible Preparations?

No special preparation is typically needed. However, avoid strenuous activity or eating heavy meals before the test if instructed by your provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

PLAC Level

Frequently asked questions

How soon after pregnancy can this test be done?
This test is most commonly performed during pregnancy, typically starting around the second trimester. Early pregnancy may not always require it unless there are specific concerns, such as a high-risk pregnancy.
What are common reasons for abnormal PLAC levels?
Elevated levels may be associated with placental abnormalities, such as placental insufficiency or preeclampsia. Lower levels could indicate potential issues like fetal distress or placental detachment, though results should always be interpreted by a healthcare provider in context.
Does diet or exercise affect PLAC levels?
There is no strong evidence that diet or exercise significantly impacts PLAC levels. However, avoid heavy meals or strenuous activity right before the blood draw if your provider recommends it.
  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