Treponema pallidum DNA [Presence], Whole Blood — Probe and Target Amplification, Qualitative
A qualitative blood test that detects DNA from the bacterium that causes syphilis. It may help confirm infection when other test results are unclear.
["Detecting Treponema pallidum DNA in blood supports a diagnosis of syphilis, but results must be interpreted with other testing."]
Key facts at a glance
- LOINC
- 21805-7
- Short code
- t(12;16)(DDIT3,FUS) Bld/T Ql
- Synonyms
- t(12;16)(DDIT3,FUS) Bld/T Ql
- Category
- thyroid
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 80
- Ref high
- 200
- Critical range
- 20 N/A – 400 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- molgen
- CPT
- 84436
- SNOMED
- 302346007
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What is this test?
This laboratory test checks a blood sample for genetic material, or DNA, from Treponema pallidum, the bacterium that causes syphilis. It is a qualitative test, meaning the result is reported as detected or not detected.
Why might I need this test?
This test may be used when a patient has signs or symptoms of syphilis, has a screening result that does not fit the clinical picture, or needs confirmation of infection. It can be especially useful when standard antibody-based tests are not conclusive.
How is the test performed?
A blood sample is collected by venipuncture and sent to a laboratory. The laboratory uses a target-amplification method with probe detection to look for Treponema pallidum DNA.
How do I prepare for the test?
No special preparation is usually needed for this blood test, and fasting is generally not required. Follow any additional instructions from your healthcare professional, particularly if the test is being ordered with other tests.
Reference range
Adult: 80-200 ng/dLN/A
Take your thyroid medication after the blood draw if applicable. No fasting required.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A detected result means that Treponema pallidum DNA was found in the blood, which supports active or untreated syphilis. A not-detected result does not completely exclude infection, especially at later stages, after treatment, or when the amount of DNA in the sample is too low to detect. Results should be interpreted with symptoms, exposure history, and other syphilis tests by the treating clinician.
Short name
Blood Treponema pallidum DNA test
Frequently asked questions
Does a detected result mean I have syphilis?
Is this the same as a rapid plasma reagin test?
Can a not-detected result rule out syphilis?
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