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Diphtheria Antitoxoid Antibody

Does this test have other names?

Anti-diphtheria test, DIPH2, DIPO, DIPE

What is this test?

This test measures the level of diphtheria antibodies in your blood.

Diphtheria is a serious infectious disease caused by C. diphtheriae bacteria. Diphtheria affects the respiratory tract, causing symptoms such as sore throat, weakness, nausea, trouble swallowing, and painful skin lesions. Without effective treatment, diphtheria can be fatal. 

Because of widespread vaccination, the disease is extremely rare in the U.S. The CDC recommends that all children be vaccinated against diphtheria with the DTaP vaccine, which also protects against tetanus and whooping cough. Because immunity can erode over time, the CDC also recommends that adolescents and adults get a booster shot every 10 years.

Why do I need this test?

You may have this test to find out whether you have or are at risk for diphtheria.

Although the disease is rarely seen in the U.S. and other developed countries, you may be at risk if:

  • You are an adult and haven't had a diphtheria booster shot

  • You recently traveled to a country where diphtheria is common

  • You recently emigrated from a country where diphtheria is widespread

What other tests might I have along with this test?

Your doctor may also order a culture test for C. diphtheriae bacteria. A positive culture test gives a definite diagnosis of diphtheria.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

Results are given in international units per milliliter (IU/mL). If you have been vaccinated against diphtheria, your minimum levels of antibodies should be at least 0.01 to 0.1 IU/mL.

If your test results show a level lower than that, you may be at risk for diphtheria. If you have certain symptoms, you may need additional tests to find out whether you actually have diphtheria.

How is this test done?

The test requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.

What might affect my test results?

Other factors aren't likely to affect your results.

How do I get ready for this test?

You don't need to prepare for this test. But be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.