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Blood Test Tracker

Milk IgE

Measures IgE antibodies to cow's milk proteins. A higher level means your body is sensitized to milk, which is not the same as having a milk allergy.

AI-verified against cited sources. Awaiting expert reviewAlso called f2LOINC 7258-7

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What it is

This test looks for IgE antibodies that recognize cow's milk. IgE is the antibody type involved in allergic reactions. Labs measure it in a blood sample and usually report the result in kU/L, often with a class from 0 to 6. The test uses an extract of milk that contains many proteins. Separate tests for single milk proteins, such as casein, are also available.

Why it matters

Milk is one of the most common food allergies, and it is more common in children than in adults. A higher milk IgE raises the chance that milk causes symptoms. But the number alone can't tell you whether you or your child will react, or how severe a reaction would be. Many people with milk IgE eat milk with no trouble. That is why clinicians read this test together with the symptom history and, sometimes, a supervised food challenge. Most children outgrow milk allergy, and levels that fall over time can be one sign of this.

If it’s high

A higher result means your blood has more IgE that recognizes milk proteins. This is called sensitization. It fits with a milk allergy, but many people are sensitized and still have milk with no symptoms. In one US study of children with milk allergy, those who kept the allergy had higher milk IgE in their first two years than those who outgrew it (median 19 vs 1.8 kU/L). That group was highly selected, and no single number predicts a reaction on its own.

Common causes

  • Cow's milk allergy, which most often starts in the first year of life
  • Sensitization to milk without any symptoms

What can help

  • Ask an allergist how to read this result alongside symptoms before changing what you or your child eat, because avoiding a food that isn't a problem can affect nutrition and quality of life
  • Ask whether a supervised food challenge, or tests for single milk proteins such as casein, would add useful information
  • If a milk allergy is confirmed, ask about an emergency action plan and how to read food labels

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 0–0.09 kU/L. Source: Labcorp, ARUP Laboratories, Quest Diagnostics, Thermo Fisher Scientific (Phadia), Journal of Allergy and Clinical Immunology.

ImmunoCAP class scale as printed by ARUP (the manufacturer's revised scale, per UR Medicine Labs 2022)

  • Class 0: absent or undetectablebelow 0.1 kU/L
  • Class 0/1: clinical relevance undetermined0.1 to under 0.35 kU/L
  • Class 1: low level0.35 to under 0.71 kU/L
  • Class 2: moderate level0.71 to under 3.51 kU/L
  • Class 3: high level3.51 to under 17.51 kU/L
  • Class 4: very high level17.51 to under 50.01 kU/L
  • Class 5: very high level50.01 to under 100.01 kU/L
  • Class 6: very high level100.01 and above kU/L

Labcorp class scale (ImmunoCAP, as printed on Labcorp sample reports dated 2016 to 2019)

  • Class 0: negativebelow 0.1 kU/L
  • Class 0/I: equivocal or low0.1 to under 0.32 kU/L
  • Class I: low0.32 to under 0.56 kU/L
  • Class II: moderate0.56 to under 1.41 kU/L
  • Class III: high1.41 to under 3.91 kU/L
  • Class IV: very high3.91 to under 19.01 kU/L
  • Class V: very high19.01 to under 100.01 kU/L
  • Class VI: very high100.01 and above kU/L

What can affect your result

  • Age: milk allergy is most common in infants and young children. In a US survey, milk sensitization was most common at ages 1 to 5 and fell sharply after age 6
  • How long milk has been avoided, and why a person was tested, can change how well a level predicts a reaction
  • Form of milk: some people react to raw milk but can eat baked milk, which the blood test can't show on its own
  • Lab and method: results from different labs or assay systems can't be compared directly
  • Antihistamines can change allergy skin test results, and the NIAID food allergy guidelines list a blood test as an option when they can't be stopped. MedlinePlus advises telling your provider about everything you take and not stopping any medicine unless your provider tells you to.
  • Results from different labs and assay systems are not directly comparable, and published risk cutoffs from one assay can't be applied to another.

When to talk to a clinician

Call 911 or your local emergency number right away for signs of a severe allergic reaction, such as trouble breathing, swelling of the tongue, lips or throat, dizziness or fainting, a fast heartbeat, or cold, clammy skin that looks pale, gray or bluish. See a clinician if milk causes hives, vomiting, stomach pain or other symptoms soon after eating, and before removing milk from a child's diet.

Questions you could ask

  • Should we recheck this over time, and how often?
  • Does baked or heated milk matter in my case?
  • How do my symptoms and this result fit together?
  • Would a supervised food challenge or a test for single milk proteins help?
  • Do I need an emergency action plan, and how should I read food labels?

Questions people ask

Does a positive milk IgE mean I'm allergic to milk?

Not by itself. The test shows sensitization. Some people with milk IgE eat milk with no trouble, and a few people with a true milk allergy have a low result. Clinicians combine the result with the symptom history and, sometimes, a supervised food challenge.

My report says Class 0 or less than 0.10. Can I rule out a milk allergy?

A result that low makes an IgE-mediated milk allergy less likely, but it doesn't rule it out. The NIAID guidelines note that undetectable levels occasionally occur in people with IgE-mediated food allergy. If the history is convincing, talk with an allergist. Lactose intolerance isn't an allergy and isn't measured by this test.

Will a child outgrow a milk allergy?

Many children do. MedlinePlus says most children grow out of allergies to milk, egg, soy and wheat. Studies differ: one found about 80% tolerant by age 5, and a later, more selected group found 5% at age 4 and 21% at age 8. An allergist can follow symptoms and levels over time.

Show the science and sources

Units

  • 1 kU/L = 1 kU/L
  • 1 kU/L = 1 UA/mL

For clinicians and researchers

Milk (ImmunoCAP f2) specific IgE is measured by fluoroenzyme immunoassay at Labcorp (602453) and ARUP (0055020) and reported in kU/L, calibrated to the WHO IgE reference preparation. Quest, Labcorp and ARUP all call below 0.10 kU/L class 0; Thermo Fisher says results above 0.1 kUA/L are indicative of sensitization, and the older 0.35 kUA/L cutoff is still used in many studies, including NHANES. The 2010 NIAID food allergy guidelines state that serum sIgE shows sensitization, not necessarily clinical allergy, that predictive values vary between studies, that values from different assay systems are not interchangeable (Wang et al. found significantly different results from ImmunoCAP, Turbo-MP and Immulite on the same sera), and that undetectable sIgE occasionally occurs in IgE-mediated food allergy. They also note high cross-reactivity between cow's milk and goat, sheep and buffalo milk, and low cross-reactivity with mare, donkey and camel milk. In the US NHANES 2005-2006 survey, sensitization to milk and egg was most common in children aged 1 to 5 and fell sharply after age 6. Natural history data: in one US referral-hospital study about 80% became tolerant by age 5, while a later study found 5% tolerant at age 4 and 21% at age 8 (a highly selected group); persistent allergy was linked to higher early sIgE (median 19.0 vs 1.8 kUA/L), and a falling sIgE over time predicted tolerance. Component tests (casein Bos d 8, alpha-lactalbumin Bos d 4, beta-lactoglobulin Bos d 5) can add information, for example on baked milk, but published cutoffs vary by study and by patient age.

LOINC 7258-7 (primary), 112997-2, 102871-1. Specimen: serum.

Sources

  1. Milk (test 602453), Labcorp
  2. Sample report for test 602453 (F002-IgE Milk), showing the class table, Labcorp
  3. Allergen, Food, Milk (Cow's) (test 0055020), ARUP Laboratories
  4. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel, Journal of Allergy and Clinical Immunology (2010)
  5. Allergy Blood Test, MedlinePlus (National Library of Medicine)
  6. Food Allergy Testing, MedlinePlus (National Library of Medicine)
  7. VALIDA project: Validation of allergy in vitro diagnostics assays (Tools and recommendations for the assessment of in vitro tests in the diagnosis of allergy), Advances in Laboratory Medicine (2020)
  8. Oral Food Challenges to Milk and Egg in Children: Associations with Skin Prick Tests and IgE Sensitization Profiles, Nutrients (2026)
  9. ImmunoCAP Specific IgE Blood Test: Allergy Test List (interpretation table and test codes), Quest Diagnostics (2017)
  10. ImmunoCAP Specific IgE blood test results: Interpretation (respiratory results interpretation guide), Thermo Fisher Scientific (Phadia) (2023)
  11. ImmunoCAP allergy: Change to Reference Interval Interpretation, UR Medicine Labs, University of Rochester Medical Center (2022)
  12. Prevalence of allergic sensitization in the United States: results from the National Health and Nutrition Examination Survey (NHANES) 2005-2006, Journal of Allergy and Clinical Immunology (2014)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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