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Alpha-Lactalbumin IgE Test

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

This blood test measures IgE antibodies directed against alpha-lactalbumin, a milk protein, and may help evaluate a possible milk allergy.

Quick summary

["A positive result can indicate sensitization to alpha-lactalbumin but must be interpreted with your symptoms and medical history."]

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

Key facts at a glance

LOINC
102135-1
Short code
A-Lactalb IgE RAST
Synonyms
A-Lactalb IgE RAST
Category
liver
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

What is this test?

Alpha-lactalbumin IgE testing measures the amount of allergen-specific IgE antibodies in a blood sample. Alpha-lactalbumin is a protein found in milk and dairy products.

Why might I need this test?

This test may be ordered if you have reactions after eating milk or dairy products, such as hives, swelling, wheezing, vomiting, or digestive symptoms. It can also help identify which milk proteins may be responsible.

How is the test performed?

A blood sample is collected and analyzed in a laboratory for IgE antibodies to alpha-lactalbumin. This is a blood test and is different from a skin-prick allergy test.

How do I prepare for the test?

Fasting is usually not required. Tell your clinician about any antihistamines or other allergy medicines you take, because they may affect interpretation; do not stop prescribed medicines unless instructed.

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

Alpha-lactalbumin IgE

Frequently asked questions

Does a positive result mean I am allergic to milk?
Not always. It indicates sensitization and must be interpreted alongside your symptoms, history, and sometimes other allergy testing.
Does this test show whether I have lactose intolerance?
No. Lactose intolerance results from reduced lactase enzyme activity, while this test measures antibodies to a milk protein.
Can I eat dairy if the result is positive?
Discuss the result with your clinician or allergist before changing your diet, especially if you have had severe reactions or need a food-challenge evaluation.
  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