Test library
Diphtheria Immunity Test
A diphtheria antibody test measures IgG antibodies to diphtheria toxoid in a blood sample. It helps assess whether a person has protective immunity from prior vaccination.
Order Diphtheria Antibody Test
Order online and visit a local collection site, or choose an at-home kit where available. No referral and no insurance required.
Order Diphtheria Antibody Test- Typical turnaround
- 1-3 business days
- Starting price
- From $129
- Results
- Confidential, online
Quick answer
A diphtheria antibody test is a blood test that measures IgG antibodies against diphtheria toxoid, the inactivated toxin used in diphtheria vaccines. It is often ordered to assess whether a person has detectable protective immunity, whether before travel, during certain occupational screening, or when vaccination records are unclear. Results are interpreted by a qualified healthcare provider.
What this test measures
Diphtheria is a bacterial infection that can affect the throat and airways, and vaccination is the main way immunity is developed. The antibody test measures the immune response to the toxoid component of the vaccine. A detectable antibody level above the laboratory protective threshold generally suggests that immunity is present at the time of testing.
The assay uses a serum sample collected from a vein and reports a quantitative IgG level, often in international units per milliliter. Laboratories compare the result with a protective threshold and may also provide a broad category such as immune or not immune. Antibody levels can decline over time, so a result reflects the current status rather than a permanent one.
People may order this test when their vaccination records are incomplete, before international travel, as part of occupational health screening, or when a provider wants to check immunity around a vaccination schedule. It does not diagnose active diphtheria infection. A qualified healthcare provider should interpret the result and discuss what it means for you.
- Diphtheria toxoid IgG antibody (antitoxin)
- Quantitative antibody titer (IU/mL)
- Protective immunity threshold
- Immune status classification
- Baseline antibody level before vaccination
- Post-vaccination antibody response
Why people order this test
- Confirm protective immunity
- Check immunity when vaccination records are unclear
- Support occupational health screening
- Prepare for a travel health consultation
- Follow up after a vaccination schedule
- Establish a baseline before a provider visit
How to prepare
No fasting is usually required. A blood sample is collected from a vein, and no special timing is generally needed. Follow the laboratory instructions and mention recent vaccinations as directed.
Understanding your results
Results are generally available within 1-3 business days. The antibody level is compared with the laboratory protective threshold, and a provider interprets what the value means for your immunity status. A result reflects the level at the time of collection.
Diphtheria Immunity Test by state
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Colorado
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Connecticut
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Delaware
Diphtheria Immunity Test across Delaware.
Florida
Diphtheria Immunity Test across Florida.
Georgia
Diphtheria Immunity Test across Georgia.
Hawaii
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Idaho
Diphtheria Immunity Test across Idaho.
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Frequently Asked Questions
What does the diphtheria antibody test measure?
It measures IgG antibodies produced in response to diphtheria toxoid, which is used in diphtheria-containing vaccines. The level helps indicate whether protective immunity is present.
Does this test diagnose an active diphtheria infection?
No. It assesses immunity rather than infection. A provider would order different tests if an active infection were suspected.
Do I need to fast before the test?
No. Fasting is not required for diphtheria antibody testing.
Can immunity decrease over time?
Yes. Antibody levels can decline, which is why some people check their status periodically or after a vaccination schedule.
What happens if the result is below the protective threshold?
A qualified healthcare provider can explain what the result means and discuss appropriate options based on your health and history.
Ready to get tested?
Order online and visit a collection site near you, or choose a mail-in kit. No referral and no insurance required.
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Every page on this site is reviewed for clarity, sourcing, and accuracy. We update our library as testing options, collection networks, and accreditation standards change.