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Rapid Plasma Reagin (RPR), Qualitative

Published: August 9, 2026Updated: August 17, 2026

A qualitative screening test used to detect antibodies associated with syphilis infection.

Quick summary

["A reactive RPR result can indicate syphilis infection but requires confirmatory testing."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
81988-8
Short code
Deprecated Peach (rPru p) 3 IgE RAST Ql
Synonyms
Deprecated Peach (rPru p) 3 IgE 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?

The Rapid Plasma Reagin (RPR) test is a screening test for syphilis. It detects reagin antibodies in a blood sample and reports the result as reactive or nonreactive.

Why might I need this test?

This test may be ordered during blood donation screening, pregnancy, or evaluation of a sexually transmitted infection. It may also be used after possible exposure to syphilis or when another screening result suggests infection.

How is the test performed?

A laboratory professional mixes the patient’s sample with a cardiolipin-containing antigen and observes whether clumping occurs. The result is interpreted qualitatively as reactive or nonreactive, although some laboratories may also report a dilution or titer when appropriate.

How do I prepare for the test?

No special preparation or fasting is usually required. Follow the instructions provided by the healthcare professional or laboratory and tell them if you may have been recently exposed to syphilis.

Reference range

Adult: 10-40 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

RPR test

Frequently asked questions

Does a reactive RPR result mean I definitely have syphilis?
No. It indicates that the screening test detected reagin antibodies, so confirmatory testing is needed. Some conditions can cause a false-positive screening result.
Can syphilis be present if the RPR result is nonreactive?
Yes, particularly if infection occurred very recently. Your clinician may recommend another test or repeat testing based on the timing of any exposure and your medical history.
Should I receive treatment before confirmatory results are available?
Treatment decisions should be made with your clinician. If syphilis is strongly suspected and the clinical situation warrants it, a clinician may begin treatment before all confirmatory results are available.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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