Tetanus IgG Antibody, Qualitative — Radioallergosorbent Test (RAST)
A legacy qualitative blood test for tetanus-specific IgG antibodies, which can indicate prior tetanus vaccination or exposure.
["Detectable tetanus-specific IgG generally supports previous vaccination or exposure, but a qualitative result does not confirm the degree of protection."]
Key facts at a glance
- LOINC
- 21553-3
- Short code
- Deprecated Tea IgG RAST Ql
- Synonyms
- Deprecated Tea IgG RAST Ql
- Category
- liver
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84484
- SNOMED
- 302774002
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This test looks for IgG antibodies against tetanus bacteria in a blood sample. The RAST format is a legacy method that has been deprecated and is now rarely used.
Why might I need this test?
It may be used to assess evidence of past tetanus vaccination or exposure when vaccination records are incomplete or immunity is uncertain. Results are considered together with your medical history and, when appropriate, other tetanus antibody tests.
How is the test performed?
A blood sample is collected and tested for tetanus-specific IgG antibodies. This qualitative version reports whether detectable antibodies were found rather than providing a precise antibody concentration.
How do I prepare for the test?
No special preparation is usually required. Tell your clinician about recent tetanus vaccines, any wound that may involve contamination, immune system conditions, and medicines that affect immune responses.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Detectable tetanus-specific IgG usually supports previous vaccination or exposure. An undetectable result may reflect no prior vaccination, waning antibodies, or a reduced immune response and should be interpreted by a clinician. This test does not diagnose active tetanus infection, and a qualitative result cannot by itself establish how well you are protected.
Short name
Tetanus IgG antibody (RAST)
Frequently asked questions
Does a positive result mean I am fully protected from tetanus?
Does this test diagnose an active tetanus infection?
Is the RAST method still commonly used?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy