A-Z Health Guide from WebMD: Medical Tests
Immunoglobulins
Test Overview
An immunoglobulins test is done to measure the level of
immunoglobulins, also known as
antibodies, in your blood.
Antibodies are substances produced by the body's
immune system in response to bacteria, viruses, or
other foreign substances, such as fungus, animal dander, or cancer cells.
Antibodies attach to the foreign substances, causing them to be destroyed by
other immune system cells. See an illustration of the
immune
system
.
Antibodies are usually specific to each type of foreign substance.
For example, antibodies produced in response to a
tuberculosis infection attach only to tuberculosis
bacteria. Antibodies also play a role in allergic reactions. Occasionally
antibodies may be produced against a person's own tissues. This is called an
autoimmune disease.
A person whose immune system produces low levels of antibodies may
be at an increased risk of developing repeated infections. A person may be born
with an immune system that produces low levels of antibodies, or the immune
system may produce low levels of antibodies in response to certain diseases,
such as cancer.
The five major types of antibodies are:
-
IgA. IgA antibodies are found mainly in areas of
the body such the nose, breathing passages, digestive tract, ears, eyes, and
vagina. IgA antibodies protect body surfaces that are exposed to the outside
from foreign organisms and substances. This type of antibody is also found in
saliva and tears. About 10% to 15% of the antibodies usually present in the
body are IgA antibodies. A small percentage of people do not make IgA
antibodies.
-
IgG. IgG antibodies are found in all body fluids.
They are the smallest but most abundant of the antibodies, normally comprising
about 75% to 80% of all the antibodies in the body. IgG antibodies are
considered the most important antibodies for fighting bacterial and viral
infections. IgG antibodies are the only type of antibody that can cross the
placenta. Therefore, the IgG antibodies of a pregnant woman can also help
protect her
baby (fetus).
-
IgM. IgM antibodies are the largest type of
antibody. They are found in blood and lymph fluid and are the first type of
antibody produced in response to an infection. They also cause other immune
system cells to produce compounds that can destroy invading cells. IgM
antibodies normally comprise about 5% to 10% of all the antibodies in the
body.
-
IgD. IgD antibodies are found in small amounts in
the tissues that line the abdominal or chest cavity of the body. The function
of IgD antibodies is not well-understood. They appear to play a role in
allergic reactions to some substances such as milk, some medications, and some
poisons.
-
IgE. IgE antibodies are found in the lungs, skin,
and mucous membranes. They cause the body to react against foreign substances
such as pollen, fungus spores, and animal dander. IgE antibody levels are often
high in people with allergies.
The levels of each type of antibody can give your health
professional information about the cause of a medical problem.
Why It Is Done
A test for immunoglobulins (antibodies) in the blood is done
to:
- Diagnose certain autoimmune diseases or
allergies.
- Diagnose certain types of cancer (such as
multiple myeloma or
macroglobulinemia) that affect immunoglobulin levels
in distinctive ways.
- Determine whether recurring infections are due
to a low level of immunoglobulins (especially IgG).
- Monitor
treatment for certain types of cancer affecting the bone
marrow.
- Monitor treatment for
Helicobacter pylori bacteria.
- Monitor
responses to immunizations to determine whether immunity is present.
This test is often done when the results of a protein
electrophoresis or total blood protein test are abnormal.
How To Prepare
There is no special preparation for this test.
How It Is Done
The health professional drawing blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- Apply a gauze pad or cotton ball over the needle site as
the needle is removed.
- Apply pressure to the site and then a
bandage.
How It Feels
You may feel nothing at all from the needle puncture, or you may
feel a brief sting or pinch as the needle goes through the skin. Some people
feel a stinging pain while the needle is in the vein. However, many people do
not feel any pain (or have only minor discomfort) once the needle is positioned
in the vein. The amount of pain you feel depends on the skill of the health
professional drawing the blood, the condition of your veins, and your
sensitivity to pain.
Risks
Blood test
There is very little risk of complications from having blood
drawn from a vein.
- You may develop a small bruise at the
puncture site. You can reduce the risk of bruising by keeping pressure on the
site for several minutes after the needle is withdrawn.
- Rarely, the
vein may become inflamed after the blood sample is taken. This condition is
called phlebitis and is usually treated with a warm compress applied several
times daily.
- Continued bleeding can be a problem for people with
bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning
medications can also make bleeding more likely. If you have bleeding or
clotting problems, or if you take blood-thinning medication, tell your health
professional before your blood is drawn.
Results
An immunoglobulins test is done to measure the level of
immunoglobulins, also known as
antibodies, in your blood.
Normal
Normal values may vary from lab to lab. The results listed below
are normal values for adults. Children have slightly different immunoglobulin
values than adults.
Immunoglobulins
| |
grams per liter (g/L)
|
milligrams per liter (mg/L)
|
milligrams per deciliter
(mg/dL)
|
| IgA |
0.7–3.0
|
row |
70–300
|
| IgG |
6.4–14.3
|
|
640–1430
|
| IgM |
0.2–1.4
|
|
20–140
|
| IgD |
|
Less than 80
|
Less than 8
|
| IgE |
|
0.1–0.4
|
0.01–0.04
|
High values
-
IgA. High levels of IgA may indicate IgA
multiple myeloma. Levels of IgA also increase in some
autoimmune diseases, such as
rheumatoid arthritis and
systemic lupus erythematosus (SLE), and in liver
diseases, such as
cirrhosis and long-term (chronic)
hepatitis.
-
IgG. High levels of IgG may indicate a long-term
(chronic) infection, such as
AIDS. Levels of IgG also increase in IgG multiple
myeloma, long-term hepatitis,
multiple sclerosis (MS), and some autoimmune diseases.
In multiple myeloma, tumor cells produce only one type of IgG antibody
(monoclonal); the other conditions cause an increase in many types of IgG
antibodies (polyclonal).
-
IgM. High levels of IgM can indicate
macroglobulinemia, early viral hepatitis,
mononucleosis, rheumatoid arthritis, kidney damage
(nephrotic syndrome), or a
parasite infection. Because IgM antibodies are the
type that form when an infection occurs for the first time, high levels of IgM
can indicate a new infection is present. High levels of IgM in a newborn
usually indicate that the baby has an infection that started in the uterus
before delivery.
-
IgD. The role of IgD in the immune system is not
well-understood. A high level may indicate IgD multiple myeloma. IgD multiple
myeloma is much less common than IgA or IgG multiple myeloma.
-
IgE. A high level of IgE can indicate a parasite
infection. Also, high levels of IgE are found in people who have allergic
reactions,
asthma,
atopic dermatitis, some types of cancer, and certain
autoimmune diseases. In rare cases, a high level of IgE may indicate IgE
multiple myeloma.
Low values
-
IgA. Low levels of IgA occur in some types of
leukemia, kidney damage (nephrotic syndrome), a
problem with the intestines (enteropathy), and a rare inherited disease that
affects muscle coordination (ataxia-telangiectasia). Some people are born with
low or absent levels of IgA antibodies, which increases their chances of
developing an autoimmune disease.
-
IgG. Low levels of IgG occur in
macroglobulinemia. In this disease, the high levels of IgM antibodies suppress
the growth of cells that produce IgG. Other conditions that can result in low
levels of IgG include some types of leukemia and a type of kidney damage
(nephrotic syndrome). On rare occasions, some people are born with a deficiency
of IgG antibodies. These people are more susceptible to infections.
-
IgM. Low levels of IgM occur in multiple myeloma,
some types of leukemia, and in some inherited types of immune diseases.
-
IgE. Low levels of IgE can occur in a rare
inherited disease that affects muscle coordination (ataxia-telangiectasia).
What Affects the Test
Factors that can interfere with your test and the accuracy of the
results include:
- Medications, such as hydralazine (Apresoline),
phenylbutazone, birth control pills, anticonvulsants (such as phenytoin),
methotrexate, aminophenazone, asparaginase, and
corticosteroids.
- Cancer treatments, both
radiation and chemotherapy.
- Receiving a blood transfusion within
the past 6 months.
- Vaccinations (immunizations), especially
vaccinations with repeat (booster) doses, given within the past 6
months.
- Using alcohol or illegal drugs.
- Having a
radioactive scan within 3 days.
What To Think About
- Immunoglobulins are unique to different
illnesses. For example, the IgM antibody for mononucleosis is different than
the IgM for
herpes. For this reason, a health professional can
look for an immunoglobulin unique to a specific illness to help diagnose that
illness.
- Different antibodies can be used to help a health
professional distinguish between a new and past infection. For example, the
presence of IgM antibodies for mononucleosis with or without IgG antibodies
indicates a new infection, whereas IgG antibodies without IgM indicates a past
infection.
- People with very low immunoglobulin levels (especially
IgA, IgG, and IgM) have an increased risk of developing an
infection.
- A very small number of people are unable to make IgA and
are at increased risk for developing a potentially life-threatening reaction to
transfused blood.
- Certain new forms of cancer treatment may try to
stimulate the production of immunoglobulins to fight cancer cells. Many of
these treatments are currently being researched.
- This test is often
done when the results of a protein electrophoresis or total blood protein test
are abnormal. For more information, see the medical tests
Serum Protein Electrophoresis (SPE) and
Total Serum Protein.
Credits
|
Author
|
Jan Nissl, RN, BS |
|
Editor
|
Susan Van Houten, RN, BSN, MBA |
|
Associate Editor
|
Tracy Landauer |
|
Primary Medical Reviewer
|
Renée M. Crichlow, MD
- Family Medicine |
|
Specialist Medical Reviewer
|
Joseph O'Donnell, MD
- Hematology |
|
Last Updated
|
October 28, 2004 |
| Immunoglobulins |
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|
|
Last updated: October 28, 2004
|
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This information is not intended to replace the advice of a doctor.
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