OVERVIEW:
Allergies are common and chronic conditions that involve the body's immune system. Normally, your immune system works to fight off viruses, bacteria, and other infectious agents. When you have an allergy, your immune system treats a harmless substance, like dust or pollen, as a threat. To fight this perceived threat, your immune system makes antibodies called immunoglobin E (IgE).
Substances that cause an allergic reaction are called allergens. Besides dust and office, other common allergens. Besides dust and pollen, other common allergens include animal dander, foods, including nuts and shellfish, and certain medicines such as penicillin. Allergy symptoms can range from sneezing and a stuffy nose to a life-threatening complication called anaphylactic shock. Allergy blood tests measure the amount of IgE antibodies in the blood. A small amount of IgE antibodies is normal. A larger amount of IgE may mean you have an allergy.
SIGNS AND SYMPTOMS OF AN ALLERGY:
- Stuffy or runny nose
- Sneezing
- Itchy watery eyes
- Hives (a rash with raised red patches)
- Diarrhea
- Vomiting
- Shortness of breath
- Coughing
- Wheezing
INTERPRETATION:
If your total IgE levels are higher than normal, it likely means you have some kind of allergy. But it does not reveal what you are allergic to. A specific IgE test will help identify your particular allergy. If your results indicate an allergy, your health care provider may refer you to an allergy specialist or recommend a treatment plan.
Your treatment plan will depend on the type and severity of your allergy. People at risk for anaphylactic shock, a severe allergic reaction that can cause death, need to take extra care to avoid the allergy-causing substance. They may need to carry an emergency epinephrine treatment with them at all times.
REFERENCE RANGE
They can range from 150 to 1,000 UI/ml, but the usually accepted upper limit is between 150 and 300 UI/ml
Allergy blood tests are used to find out if you have an allergy. One type of test called a total IgE test measures the overall number of IgE antibodies in your blood. Another type of allergy blood test called a specific IgE test measures the level of IgE antibodies in response to individual allergens.
Common Airborne Allergens
Some of the most common things people are allergic to are airborne (carried through the air):
- Dust mites are microscopic insects that live all around us and feed on the millions of dead skin cells that fall off our bodies every day. They're the main allergic component of house dust. Dust mites are present year-round in most parts of the United States and live in bedding, upholstery, and carpets.
- Pollen is a major cause of allergies (a pollen allergy is often called hay fever or rose fever). Trees, weeds, and grasses release these tiny particles into the air to fertilize other plants. Pollen allergies are seasonal, and the type of pollen someone is allergic to determines when symptoms happen. Pollen counts measure how much pollen is in the air and can help people with allergies predict how bad their symptoms might be on any given day. Pollen counts are usually higher in the morning and on warm, dry, breezy days, and lowest when it's chilly and wet.
- Molds are fungi that thrive both indoors and outside in warm, moist environments. Outdoors, molds can be found in poor drainage areas, such as in piles of rotting leaves or compost piles. Indoors, molds thrive in dark, poorly ventilated places such as bathrooms and damp basements. Molds tend to be seasonal, but some can grow year-round, especially those indoors.
- Pet allergens are caused by pet dander (tiny flakes of shed skin) and animal saliva. When pets lick themselves, the saliva gets on their fur or feathers. As the saliva dries, protein particles become airborne and work their way into fabrics in the home. Pet urine also can cause allergies in the same way when it gets on airborne fur or skin, or when a pet pees in a spot that isn't cleaned.
- Cockroaches are also a major household allergen, especially in inner cities. Exposure to cockroach-infested buildings may be a major cause of the high rates of asthma in inner-city kids.
Common Food Allergens
- Cow's milk (or cow's milk protein). Between 2% and 3% of children younger than 3 years old are allergic to the proteins found in cow's milk and cow's milk-based formulas. Most formulas are cow's milk-based. Milk proteins also can be a hidden ingredient in prepared foods. Many kids outgrow milk allergies.
- Eggs. Egg allergy can be a challenge for parents. Eggs are used in many of the foods kids eat — and in many cases they're "hidden" ingredients. Kids tend to outgrow egg allergies as they get older.
- Fish and shellfish. These allergies are some of the more common adult food allergies and ones that people usually don't outgrow. Fish and shellfish are from different families of food, so having an allergy to one does not necessarily mean someone will be allergic to the other.
- Peanuts and tree nuts. Peanut allergies are on the rise, and as are allergies to tree nuts, such as almonds, walnuts, pecans, hazelnuts, and cashews. Most people do not outgrow peanut or tree nut allergies.
- Soy. Soy allergy is more common among babies than older kids. Many infants who are allergic to cow's milk are also allergic to the protein in soy formulas. Soy proteins are often a hidden ingredient in prepared foods.
- Wheat. Wheat proteins are found in many foods, and some are more obvious than others. Although wheat allergy is often confused with celiac disease, there is a difference. Celiac disease is a sensitivity to gluten (found in wheat, rye, and barley). But a wheat allergy can do more than make a person feel ill — like other food allergies, it also can cause a life-threatening reaction.
Other Common Allergens
- Insect allergy. For most kids, being stung by an insect means swelling, redness, and itching at the site of the bite. But for those with insect venom allergy, an insect sting can cause more serious symptoms.
- Medicines. Antibiotics are the most common type of medicines that cause allergic reactions. Many others, including over-the-counter medicines (those you can buy without a prescription), also can cause allergic reactions.
- Chemicals. Some cosmetics or laundry detergents can make people break out in hives. Usually, this is because someone has a reaction to the chemicals in these products, though it may not always be an allergic reaction. Dyes, household cleaners, and pesticides used on lawns or plants can also cause allergic reactions in some people.
