VDRL / RPR (non-treponemal syphilis test)

What it measures

Detects reagin antibodies against cardiolipin released in syphilis. It is used for screening and, as a titre, to follow disease activity and treatment response.

Specimen and preparation

• Specimen: Serum (CSF for VDRL in neurosyphilis)
• Tube: Red top

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Primary, secondary or early latent syphilis
• Biological false positive: pregnancy, SLE, antiphospholipid syndrome, malaria, HIV, TB, older age
• Congenital syphilis (infant titre fourfold above mother's)
• Neurosyphilis (CSF VDRL reactive)

Method

Flocculation (slide or card), titred by doubling dilution

Good to know

Confirm reactive results with a treponemal test. A fourfold fall in titre indicates successful treatment; prozone can cause false negatives.

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