Titer – antibodies; Serum antibodies
Antibody titer is a laboratory test that measures the level of antibodies in a blood sample. The antibody titer is a test that detects the presence and measures the number of antibodies within a person’s blood. The amount and diversity of antibodies correlate to the strength of the body’s immune response.
How the Test is Performed
A blood sample is needed.
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 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
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:
- Excessive bleeding
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
FAQ
What is an antibody titer test?
- Antibody titer is a laboratory test that measures the level of antibodies in a blood sample.
What does it mean if titers are positive?
- Titers are blood tests that check your immune status to vaccinations or diseases you may have received in the past. If you’re titers results are positive, it means that you have adequate immunity to a particular infectious disease. Therefore, you do not need to get that particular vaccine.
What does a higher antibody titer mean?
- In certain conditions, a low titer may essentially indicate the efficient removal of infectious pathogens by the immune system. In contrast, a high titer may simply be due to the presence of residual antibodies from a previous infection, or unsuccessful attempts to form antigen-antibody complexes.
How is antibody titer determined?
- The titer is determined by serially diluting the serum fraction of blood and assaying (testing) each dilution for the antibody of interest (for example, equine influenza virus antibodies). The last dilution of a serum sample that responds in the assay determines the titer.
Why do I have antibodies in my blood?
- Red blood cell antibodies may show up in your blood if you are exposed to red blood cells other than your own. This usually happens after a blood transfusion or during pregnancy, if a mother’s blood comes in contact with her unborn baby’s blood.
How long do COVID-19 antibodies last?
- Early on, researchers thought that natural immunity to COVID-19 only lasted for about 2 to 3 months before fading. As the pandemic continued, experts started finding evidence that natural immunity could last for almost a year after infection. But along came the Omicron variant — and that’s changed everything.
How often should titers be checked?
- How often should titers be checked? A three-year interval is appropriate for the majority of adult dogs and cats when quantitative tests are used. The manufacturers of in-clinic (“yes/no”) screening tests recommend they be used annually.
How long do titers take to result?
- A titer test is performed using a blood sample. There is no fasting or special prep required for the test. The sample is sent to a lab, and the results are normally available within 24 to 72 hours.
How do I read my titer’s results?
- The USDA considers a titer of ≥1:4 to be positive. A result of <1:2 is equivalent to a negative @ 1:4 or 1:8 result. A titer of >1:128 may indicate a recent infection. A titer of ≥1:320 may indicate a recent infection.
What does it mean if you have antibodies to Covid?
- A positive antibody test result could mean you previously had a SARS-CoV-2 infection or COVID-19. A positive antibody test could also mean the test is detecting antibodies in your blood in response to your COVID-19 vaccine. Not all SARS-CoV-2 antibody tests will detect antibodies in response to a COVID-19 vaccine.
How much blood is needed for a titer test?
- Your test result will have an explanation of what your pet’s test result means. But if you want to know more, here’s the test in a nutshell: First, one mL of blood is drawn. The sample is then diluted. Titer levels expressed as ratios, indicate how many times blood can be diluted before no antibodies are detected.
What is the difference between a titer and a vaccine?
- A titer may be used to prove immunity to disease. A blood sample is taken and tested. If the test is positive (above a particular known value) the individual has immunity. If the test is negative (no immunity) or equivocal (not enough immunity) you need to be vaccinated.
What does a negative titer mean?
- Understanding the test results
- That means that you have adequate immunity to a particular infectious disease. If titer results are negative, which means there is no immunity to a specific disease, your school or work may require you to get a vaccination.
What vaccines can you get titers for?
The standard diseases tested through an immunization titer test include:
