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Milk IgG Immunoglobulin (Serum or Plasma)

Published: August 9, 2026Updated: August 17, 2026

This test measures the level of Immunoglobulin G (IgG), a type of antibody found in breast milk, which can help assess maternal immune status or evaluate milk composition for infants.

Quick summary

["IgG in breast milk supports infant immune protection and may be checked for specific medical reasons."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
102438-9
Short code
Milk IgE RAST
Synonyms
Milk IgE RAST
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
rast
CPT
84484
SNOMED
302774002
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 This Test Might Be Ordered

Your healthcare provider may recommend this test if you’re breastfeeding and want to ensure your milk contains adequate antibodies to support your baby’s immune system. It could also be used in research or specialized clinical settings to study milk composition.

What to Expect Before the Test

No special preparation is needed. Blood is drawn from a vein in your arm, similar to other blood tests. If testing milk, a small sample is collected directly from your breast.

What the Results Mean

Results help determine if your milk contains sufficient IgG for your baby’s immune needs. Very low levels might prompt further discussion about breastfeeding support or alternative feeding methods.

Common Reasons for Testing

This test is less commonly performed in routine clinical practice but may be used in specialized scenarios, such as evaluating immune transfer in preterm infants or studying milk protein profiles.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Milk Antibody Level

Frequently asked questions

What does a low IgG level in my milk mean?
A low IgG level may indicate that your milk contains fewer antibodies than usual, which could be discussed with your healthcare provider if you’re concerned about your baby’s immune support.
How often should I get this test?
This test is not routinely recommended for all breastfeeding mothers. Your provider will determine if testing is necessary based on your specific medical situation or research needs.
Can I take anything special to prepare for this test?
No special preparation is required. Blood or milk samples are collected as needed, and results are interpreted by your healthcare team.
  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 17, 2026. · Read our editorial policy