Definition
Antibody titer is a laboratory test that measures the level of antibodies in a blood sample.
Alternative Names
Titer - antibodies; Serum antibodies
How the Test is Performed
How to Prepare for the Test
No special preparation is necessary for this test.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
The antibody level (titer) in the blood tells your health care provider whether or not you have been exposed to an antigen, or something that the body thinks is foreign. The body uses antibodies to attack and remove foreign substances.
In some situations, your provider may check your antibody titer to see if you had an infection in the past (for example, chickenpox or measles) or to decide which vaccines you need.
The antibody titer is also used to determine:
- The strength of an immune response to the body's own tissue in diseases such as systemic lupus erythematosus (SLE) and other autoimmune disorders
- If you need a booster vaccine
- Whether a vaccine you had before helped your immune system protect you against the specific disease
- If you have had a recent or past infection, such as mononucleosis or viral hepatitis
Normal Results
Normal values depend on the antibody being tested.
If the test is being done to look for antibodies against your own body tissues, the normal value would be zero or negative. In some cases, a normal level is below a specific number.
If the test is being done to see if a vaccine fully protects you against a disease, the normal result depends on the specific value for that immunization.
Negative antibody tests can help rule out certain infections.
Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results depend on which antibodies are being measured.
Abnormal results may be due to:
- Autoimmune disease
- Failure of a vaccine to fully protect you against a certain disease
- Immune deficiency
- Viral infections
Risks
There is little risk involved with having your blood taken. Veins vary in size from one person 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.
Risks associated with having blood drawn are slight, but may include:
References
Kroger AT, Pickering LK, Mawle A, Hinman AR, Orenstein WA. Immunization. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 316.
McPherson RA, Riley RS, Massey HD. Laboratory evaluation of immunoglobulin function and humoral immunity. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Philadelphia, PA: Elsevier; 2017:chap 46.
Nadeau KC. Approach to the patient with allergic or immunologic disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 230.
