Lab test

Beta Lactoglobulin (BLG) Allergy Test

A beta-lactoglobulin allergy test measures allergen-specific IgE antibodies produced against beta-lactoglobulin, a major whey protein in cow's milk.

Typical price

From $49

Results

1-3 business days

Preparation

See preparation notes below

Sample

Blood draw or sample collection at a local center

A beta-lactoglobulin allergy test measures allergen-specific IgE antibodies produced against beta-lactoglobulin, a major whey protein in cow's milk. Beta-lactoglobulin is one of the principal milk allergens and is found in whey and many dairy products. A healthcare provider may order it after a reaction to milk or dairy, or as part of a broader milk protein panel that also includes casein and alpha-lactalbumin. It is a screening tool and is interpreted with your clinical history.

• Beta-lactoglobulin-specific IgE Antibodies produced against beta-lactoglobulin, a major whey protein in cow's milk; used to assess sensitization.

• People who develop hives, itching, or swelling after consuming milk or whey
• Individuals with vomiting, diarrhea, or abdominal discomfort linked to dairy
• Those with eczema or skin reactions that flare after milk products
• People who suspect a whey protein reaction rather than a casein reaction
• Anyone being evaluated as part of a broader cow's milk allergy workup

• No fasting is required before this test
• The sample can be collected at any time of day
• Inform the provider about all medications and supplements you take
• Drinking water beforehand can make the blood draw easier

Results are reported as an IgE level or class for beta-lactoglobulin. An elevated value may indicate sensitization to this whey protein, but a positive result alone does not prove a clinical allergy. A low or undetectable level makes reactivity to beta-lactoglobulin less likely, though it does not exclude allergy to other milk proteins such as casein. Milk proteins can resemble those in other mammalian milks, so a provider may consider cross-reactivity. Discuss results with a healthcare provider before changing your diet.

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