How is cow's milk allergy diagnosed?

Your doctor can see the baby and might be able to diagnose using what you tell then. It is important to tell your doctor anything which you think might be worrying.

There are also a few tests that can be done to confirm whether your child has cow's milk allergy.

Elimination diets might be a good way of seeing what food causes a particular reaction. This involves removing cow's milk from the child's diet (and your own if you are breastfeeding), and seeing if any symptoms disappear. On re-introducing cow's milk, you could see problems starting up again. For formula-fed babies, this is easily achieved by using hypoallergenic formulas – the milk proteins are broken down into their smaller components called amino acids. An example of a hypoallergenic milk formula is Neocate, and is given on prescription. These formulas cannot elicit a reaction, but still provide all the nutritional benefit for the baby. In older infants, an elimination diet can be achieved by weaning the child off milk and any other dairy products. Elimination diets are often difficult to maintain and should be done in consultation with a dietician, but they are the most reliable way of checking whether your baby has cow's milk protein allergy.

The radioallergosorbent test (RAST) is a lab-based test, and involves reacting IgE (a molecule in the blood that is involved with immunity and responsible for causing allergies) with milk proteins. RASTs are expensive and difficult to do, but are more reliable than skin prick tests.

A skin prick test might be appropriate as well. This involves introducing a small amount of milk or proteins in milk under the skin to see if a reaction develops. If your child is allergic to milk proteins, you would see changes in the skin, such as a “wheal and flare” - an irregular, blanched area of skin surrounded by a reddened area. However, it is not extremely reliable. 50% of children who test positive for cow's milk allergy using a skin test have a false positive, meaning that although the test indicates that they have cow's milk allergy, they do not. On the other hand, less than 5 % of children who get a negative test result do have cow's milk protein allergy.

Allergies Treatment Guide Index:

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• What is cow's milk allergy?
• What are the signs and symptoms of cow's milk allergy?
• Who gets cow's milk allergy?
• How is cow's milk allergy diagnosed?
• How is cow's milk allergy managed?

• What about goat's milk?
• How can cow's milk allergy be prevented?
• What is the difference between milk allergy and lactose intolerance?
• What is lactose overload?

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