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Date of last update: 10/12/2017.

Forum Name: Sexually Transmitted Diseases

Question: syphilis screening test

 toycar - Wed Jul 25, 2007 1:48 am

hi! i'm a registered medical technologist from the philippines. i would just like to ask if it is possible that RPR and VDRL gives different results. a patient in an industrial clinic tested for RPR and the result is reactive at 1:2 dilution, the same patient tested at a known hospital here and the VDRL result is non-reactive. how is it possible that the 2 screening tests yielded different results wherein RPR is just a modified procedure of VDRL? i've read books but to no avail haven't found the answer, even in school they haven't taught us about this. i hope you could help me about this since it really bothers me a lot. thank you.
 Dr. Chan Lowe - Tue Jul 31, 2007 4:35 pm

User avatar Hi Toycar,

The VDRL and RPR both test for antibodies, although not exactly the same ones. The RPR titer of 1:2 is not indicative of a high amount of antibodies in the blood.

So, there are a few possible reasons he may have had a + RPR and negative VDRL. It may be that he is not making the VDRL antibody or it is too low to detect. The latter is definitely possible with an RPR titer of 1:2.

Best wishes.

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