What Is a Blood Test?
A blood test is when a sample of blood
is taken from the body to be tested in a lab. Doctors order blood tests to check things
such as the levels of glucose,
hemoglobin, or white blood cells. This can help them detect problems like a disease
or medical condition. Sometimes, blood tests can help them see how well an organ (such
as the liver or kidneys)
is working.
What Is an Allergen-Specific Immunoglobulin E Test?
An allergen-specific immunoglobulin E (IgE) test measures the levels of different
IgE antibodies. Antibodies are made by the immune
system to protect the body from bacteria,
viruses, and allergens.
IgE antibodies are normally found in small amounts in the blood, but higher amounts
can be found when the body overreacts to allergens.
IgE antibodies are different depending on what they react to. An allergen-specific
IgE test can show what the body is reacting to.
Why Are IgE Tests Done?
An allergen-specific IgE test may be done to look for some kinds of allergies.
These include types of food,
animal dander, pollen,
mold, medicine, dust mites, latex,
or insect venom.
How Should We Prepare for an IgE Test?
Your child should be able to eat and drink normally unless also getting other tests
that require fasting beforehand. Tell your doctor about any medicines your child takes
because some drugs might affect the test results.
Wearing a T-shirt or short-sleeved shirt for the test can make things easier for
your child, and you also can bring along a toy or book as a distraction.
How Is an IgE Test Done?
Most blood tests take a small amount of blood from a vein. To do that, a health
professional will:
- clean the skin
- put an elastic band (tourniquet) above the area to get the veins to swell with
blood
- insert a needle into a vein (usually in the arm inside of the elbow or on the
back of the hand)
- pull the blood sample into a vial or syringe
- take off the elastic band and remove the needle from the vein
In babies, blood draws are sometimes done as a "heel stick collection." After cleaning
the area, the health professional will prick your baby's heel with a tiny needle (or
lancet) to collect a small sample of blood.
Collecting a sample of blood is only temporarily uncomfortable and can feel like
a quick pinprick.

