MedlinePlus Medical Encyclopedia: Antibody titer

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Antibody titer

Contents of this page:
Illustrations Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Illustrations

Antibody titer

Alternative names Return to top

Titer - antibodies; Serum antibodies

Definition Return to top

A test to measures the presence and amount of antibodies in blood against a particular type of tissue, cell, or substance.

How the test is performed Return to top

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in air-tight vials or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

How to prepare for the test Return to top

No special preparation is necessary for this test.

How the test will feel Return to top

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed Return to top

The antibody level in the blood is a reflection of the body's past experience or exposure to an antigen, or something that the body does not recognize as belonging to itself. The body uses antibodies to attack and eliminate the foreign matter.

Every living cell has different protein markers on its surface. The body's immune system identifies those cells that are not part of itself by these surface proteins.

Occasionally, the body makes an error and begins to recognize its own tissue as being non-self, or foreign. This leads to an immune response against that tissue type, cell, or substance that is part of the body. This is known as autoimmunity.

Levels of antibodies in the blood (also known as the antibody titer) are measured to determine:

the strength of an immune response to the body's own tissue in diseases such as SLE, and other autoimmune disorders.
the need for a booster immunization, or if a recent administration caused a strong enough response from the immune system, bringing your antibody titer against a particular disease up to a preventative level.

Normal Values Return to top

This depends of the antibody being tested. If your health care provider is testing for antibodies against your own tissue, then the normal value would be zero or negative.

If your health care provider is testing to see if your immunization brought your antibody titer up to a preventative level, then that would be a given value determined by that immunization.

What abnormal results mean Return to top

If your health care provider is testing for antibodies against your own tissue, abnormal results would show a positive antibody titer. This means that your immune system is fighting its own tissue, cells, or substances.

If your health care provider is testing to see if your immunization brought your antibody titer up to a preventative level, an abnormal result would indicate that your body has not mounted an adequate response against the immunization, and you are not adequately protected from the disease.

What the risks are Return to top

Risks associated with venipuncture are slight:

excessive bleeding
fainting or feeling light-headed
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins

Special considerations Return to top

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Update Date: 11/3/2003

Updated by: Sherry Woodhouse, M.D., Department of Pathology and Laboratory Medicine, Cleveland Clinic Florida, Weston, FL. Review provided by VeriMed Healthcare Network.

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