What type of doctor checks for food allergies

If your GP suspects a food allergy, you may be referred to an allergy clinic for testing.

The tests needed can vary, depending on the type of allergy:

  1. if the symptoms developed quickly (an IgE-mediated food allergy) – you’ll probably be given a skin-prick test or a blood test
  2. if the symptoms developed more slowly (non-IgE-mediated food allergy) – you’ll probably be put on a food elimination diet

Skin-prick testing

During a skin-prick test, drops of standardised extracts of foods are placed on the arm.

The skin is then pierced with a small lancet, which allows the allergen to come into contact with the cells of your immune system.

Occasionally, your doctor may perform the test using a sample of the food thought to cause a reaction.

Itching, redness and swelling generally indicates a positive reaction. This test is generally painless.

A skin-prick test does own a little theoretical chance of causing anaphylaxis, but testing will be carried out where there are facilities to deal with this – usually an allergy clinic, hospital, or larger GP surgery.

Blood test

An alternative to a skin-prick test is a blood test, which measures the quantity of allergic antibodies in the blood.

Food elimination diet

In a food elimination diet, the food thought to own caused the allergic reaction is withdrawn from your diet for 2 to 6 weeks.

What type of doctor checks for food allergies

The food is then reintroduced.

If the symptoms go away when the food is withdrawn but return once the food is introduced again, this normally suggests a food allergy or intolerance.

Before starting the diet, you should be given advice from a dietitian on issues such as:

  1. the food and drinks you need to avoid
  2. if any alternative sources of nutrition are needed
  3. how you should interpret food labels
  4. how endless the diet should final

Don’t attempt a food elimination diet by yourself without discussing it with a qualified health professional.


Characteristics of Patients with Food Allergies

Most patients with food allergies own an atopic disorder; however, only 10 percent of patients with atopic disorders own food allergies  A family history of food allergy or other atopic disorders increases the risk of developing a food allergy.

Genetic predisposition, including specific haplotypes, has been identified for some common food allergies. The oral allergy syndrome is confined to patients who own allergic rhinitis or asthma.

What type of doctor checks for food allergies

Table 2 lists historical factors that increase the risk of food allergies

View/Print Table

Table 2

Characteristics of Patients with Food Allergies

Most patients with food allergies own an atopic disorder; however, only 10 percent of patients with atopic disorders own food allergies  A family history of food allergy or other atopic disorders increases the risk of developing a food allergy.

Genetic predisposition, including specific haplotypes, has been identified for some common food allergies. The oral allergy syndrome is confined to patients who own allergic rhinitis or asthma. Table 2 lists historical factors that increase the risk of food allergies

View/Print Table

Table 2

Historical Factors that Increase the Risk of Food Allergy

History of reaction within minutes to hours of ingestion

Inadvertent ingestions of the same food own produced similar reactions on repeated exposure

Lack of other possible explanations for the reaction besides food allergy

Suspected food is known to be a higher risk for food allergies

Symptom onset in baby or young child

Personal or family history of atopic dermatitis, asthma, allergic rhinitis, or food allergies

Table 2

Historical Factors that Increase the Risk of Food Allergy

History of reaction within minutes to hours of ingestion

Inadvertent ingestions of the same food own produced similar reactions on repeated exposure

Lack of other possible explanations for the reaction besides food allergy

Suspected food is known to be a higher risk for food allergies

Symptom onset in baby or young child

Personal or family history of atopic dermatitis, asthma, allergic rhinitis, or food allergies


Pathophysiology

Despite high acidity in the stomach and enzyme activity, 2 percent of ingested food is absorbed through the intestine in a form that is immunologically intact enough to produce a food allergy.4 However, most patients own oral tolerance (an athletic nonresponse to antigens delivered orally) and do not ever develop a reaction.

Oral tolerance may happen because of the way intestinal epithelial cells present the antigen to mucosal lymphatic cells. Low doses of intestinal food antigens preferentially increase regulatory T cell production within the intestinal lymphoid tissue. These regulatory T cells secrete suppressive cytokines that decrease inflammatory reactions. Infants and young children own a more immature mucosal gut barrier and immune response; therefore, a larger percentage of ingested food is absorbed intact.

What type of doctor checks for food allergies

This is believed to account for the increased prevalence of food allergies in this population.4


Food Allergies: Detection and Management

KURT KUROWSKI, MD, The Chicago Medical School at Rosalind Franklin University of Medicine and Science, North Chicago, Illinois

ROBERT W. BOXER, MD, Rush North Shore Medical Middle, Skokie, Illinois

Am Fam Physician.  Jun 15;77(12)

Patient information: See related handout on food allergies, written by the authors of this article.

Family physicians frolic a central role in the suspicion and diagnosis of immunoglobulin E-mediated food allergies, but they are also critical in redirecting the evaluation for symptoms that patients are falsely attributing to allergies.

Although any food is a potential allergen, more than 90 percent of acute systemic reactions to food in children are from eggs, milk, soy, wheat, or peanuts, and in adults are from crustaceans, tree nuts, peanuts, or fish. The oral allergy syndrome is more common than anaphylactic reactions to food, but symptoms are transient and limited to the mouth and throat. Skin-prick and radioallergosorbent tests for specific foods own about an 85 percent sensitivity and 30 to 60 percent specificity. Intradermal testing has a higher false-positive rate and greater risk of adverse reactions; therefore, it should not be used for initial evaluations. The double-blind, placebo-controlled food challenge remains the most specific test for confirming diagnosis.

Treatment is through recognition and avoidance of the responsible food. Patients with anaphylactic reactions need emergent epinephrine and instruction in self-istration in the event of inadvertent exposure.

What type of doctor checks for food allergies

Antihistamines can be used for more minor reactions.

Food allergies affect 4 to 5 percent of children and 2 to 3 percent of adults, yet untrue attribution of symptoms to food allergy remains a problem.1,2 Population-based studies of children and adolescents own shown that only 10 percent of those who believe they own food allergy can be proven to own one.1 Disorders associated with food allergy, such as eosinophilic esophagitis, are being increasingly recognized, and some other previously known disorders, such as gastroesophageal reflux disease in infants, are being increasingly attributed to food allergies.3 Food allergy is the leading cause of nondrug-related anaphylaxis.


Foods Most Likely to Produce Food Allergies

Although any food is a potential allergen, the foods in Table 1 account for more than 90 percent of every systemic food allergies.2,5 Fruits and vegetables can also produce allergies, but they tend to be milder reactions.

Seeds (e.g., sesame, sunflower) own been known to cause severe reactions.6,7 Although much less common, allergy to other foods is possible, with manifestations in almost any organ system. Allergy to food additives is also possible, but rare. Food additive allergy should be suspected when the patient reports allergic symptoms after ingestion of a variety of foods with no shared proteins, and when no reaction occurs with a homemade version of the same foods.8 Genetic manipulation of food can also potentially produce proteins that will cross-react with the immunoglobulin E (IgE) of a patient with a food allergy.9

Most patients are allergic to between one and three foods.

This does not include the cross-reactions to similar proteins that can be common in some food groups. For example, almost every patients who are allergic to cow’s milk will also be allergic to sheep’s or goat’s milk. Most patients who are allergic to shrimp will also react to other crustaceans. Some patients with a latex allergy will react to banana, kiwi, or avocado.

View/Print Table

Table 1

Foods Most Likely to Produce Food Allergies

Although any food is a potential allergen, the foods in Table 1 account for more than 90 percent of every systemic food allergies.2,5 Fruits and vegetables can also produce allergies, but they tend to be milder reactions.

Seeds (e.g., sesame, sunflower) own been known to cause severe reactions.6,7 Although much less common, allergy to other foods is possible, with manifestations in almost any organ system. Allergy to food additives is also possible, but rare. Food additive allergy should be suspected when the patient reports allergic symptoms after ingestion of a variety of foods with no shared proteins, and when no reaction occurs with a homemade version of the same foods.8 Genetic manipulation of food can also potentially produce proteins that will cross-react with the immunoglobulin E (IgE) of a patient with a food allergy.9

Most patients are allergic to between one and three foods.

This does not include the cross-reactions to similar proteins that can be common in some food groups. For example, almost every patients who are allergic to cow’s milk will also be allergic to sheep’s or goat’s milk. Most patients who are allergic to shrimp will also react to other crustaceans.

What type of doctor checks for food allergies

Some patients with a latex allergy will react to banana, kiwi, or avocado.

View/Print Table

Table 1

Most Common Food Allergies in Children and Adults

Children Adults

Egg

Milk

Soy

Wheat

Peanut

Crustaceans (e.g., shrimp, crab, lobster)

Tree nuts

Peanut

Fish

Table 1

Most Common Food Allergies in Children and Adults

Children Adults

Egg

Milk

Soy

Wheat

Peanut

Crustaceans (e.g., shrimp, crab, lobster)

Tree nuts

Peanut

Fish


Alternative tests

There are several shop-bought tests available that claim to detect allergies, but should be avoided.

They include:

  1. vega testing – claims to detect allergies by measuring changes in your electromagnetic field
  2. hair analysis – claims to detect food allergies by taking a sample of your hair and running a series of tests on it
  3. kinesiology testing – claims to detect food allergies by studying your muscle responses
  4. alternative blood tests (leukocytotoxic tests) – claim to detect food allergies by checking for the «swelling of white blood cells»

Many alternative testing kits are expensive, the scientific principles they are allegedly based on are unproven, and independent reviews own found them to be unreliable.

They should therefore be avoided.

Diagnosing food allergies can be as complicated as the medical condition itself. Symptoms of food allergy can vary from person to person, and a single individual may not always experience the same symptoms during every reaction. Food allergic reactions can affect the skin, respiratory tract, gastrointestinal tract, and/or cardiovascular system, and people may develop food allergies at diverse ages.

Diagnostic food allergy testing offers clues about the causes of symptoms, but it cannot determine whether someone has a food allergy with absolute certainty without an oral food challenge.

Still, when a food allergy is suspected, it’s critically significant to consult an allergist who can determine which food allergy tests to act out, determine if food allergy exists, and counsel you on food allergy management once the diagnosis has been made.

To make a diagnosis, allergists enquire detailed questions about the history of allergy symptoms. Be prepared to answer questions about the specific foods and the quantities you ate, the length of time that it took for symptoms to develop, the symptoms themselves, and how endless they lasted.

The allergist will generally order a blood test (such as an ImmunoCAP test) and/or act out a skin prick food allergy test, both of which indicate whether food-specific IgE antibodies are present in your body.

Skin prick tests are conducted in a doctor’s office and provide results within minutes.

What type of doctor checks for food allergies

A nurse or the allergist isters these tests on the patient’s arm or back by pricking the skin with a sterile little probe that contains a tiny quantity of the food allergen. The tests, which are not painful but can be uncomfortable (mostly itchy), are considered positive if a wheal (resembling a mosquito bite bump) develops at the site.

Blood tests, which are less sensitive than skin prick tests, measure the quantity of IgE antibody to the specific food(s) being tested. Results are typically available in about one to two weeks and are reported as a numerical value.

Your allergist will interpret these results and use them to aid in a diagnosis. While both of these diagnostic tools can signal a food allergy, neither is conclusive.

A positive test result to a specific food does not always indicate that a patient will react to that food when it’s eaten. A negative test is more helpful to law out a food allergy. Neither test, by its level of IgE antibodies or the size of the wheal, necessarily predicts the severity of a food allergic reaction.

One extremely significant point to realize with food skin testing is a positive does not necessarily mean you’re allergic.

Dr. Rohit Katial

Together with the patient’s history, an allergist may use these tests to make a food allergy diagnosis.

What type of doctor checks for food allergies

In some cases, an allergist may wish to conduct an oral food challenge, which is the gold standard for food allergy diagnosis. However, the procedure can be costly, time-consuming, and in some cases is potentially dangerous, so it is not routinely performed.

During an oral food challenge, the patient is fed gradually increasing amounts of the suspected allergy-causing food over a period of time under strict supervision by an allergist. Emergency medication and emergency equipment must be on hand during this procedure.

Oral food challenges may also be performed to determine if a patient has outgrown a food allergy.

Allergists are specially trained to assist you take control of your allergies and asthma, so you can live the life you desire.

Discover an allergist to assist you diagnose your food allergies.

This sheet was reviewed and updated as of 2/12/


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