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May 27, 2006

Dear Doc:

I am confused about DNA PCR vs RNA PCR. Which one has the higher rate of false positive?

I had a DNA PCR test done which indicated 9,130 IU/mL.

The PCR was done because my first round of blood work indicated HIV antibodies. The doctor was convinced it was a false positive (I dont fall into any risk categories) and retook my blood work again and everything came back clear except for the DNA PCR (9,130 IU/mL).

I've read a lot of research that PCR tests in general and found they are extremely vulnerable to cross contamination. In your responses to forum readers it seems that RNA PCR are more likely to be false positive than DNA PCR, correct? Or would you say ANY KIND OF PCR TESTING has a higher rate of false positives? Im confused about the rate of false positive results between both tests and would appreciate it if you can clarify.

Please know I am frequent donator to your charity. In fact, it is the only one I will donate to.

Take care of yourself, Doc.

May God bless you and all those you touch daily.

My very best, Dave.

Response from Dr. Frascino

Hello Dave,

These two tests (DNA PCR and RNA PCR) measure two different things and therefore you cannot compare one to the other as far as false-positive are concerned.

In your particular case, you had no risk factors; consequently, you should not have even needed an HIV test. However, your screening test "indicated HIV antibodies." Assuming this was an ELISA test, the next test to run should have been a Western Blot, not a PCR.

Your follow-up tests (presumably a repeat ELISA) came back negative as would be expected from your history of no risk. That should have been the end of your testing saga and a happy ending at that! However, for some reason A DNA PCR was run and came back 9,130. I would have to conclude this test was a laboratory error or a "false positive."

So, Dave, what should you do now? If in fact you have absolutely no potential risk factors for HIV, I would suggest you stop testing. If, on the other hand, you have some potential risk, repeat your ELISA in one month. If negative, you are definitely "all clear." If positive, you'll need a Western Blot to confirm your positive status.

HIV screening, when done properly, is not difficult. However, done improperly, it can produce results that can be not only confusing but also anxiety provoking.

Dave, thanks for your contributions!

Be well. Stay well.

Dr. Bob

Symptoms definitely not same as disease
Help this X-man

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