[Question #3126] NAT RNA vs. RNA Qualitative

38 months ago

Dr. Handsfield responded to questions I had in late November regarding testing and what we agreed was a no risk exposure for HIV.  Just curious though, it was stated then that a NAT RNA combined with the  duo test would be conclusive at 4 weeks, which is good.  Is a NAT RNA the same as a PCR RNA and a Qualitative RNA?  If not, are any of the "RNA Tests" combined with the duo Antigen/antibody also conclusive at 4 weeks (if negative)?

Thanks for the education.


Edward W. Hook M.D.
Edward W. Hook M.D.
38 months ago
Welcome back to the Forum.  I'll be answering your question this time.  I agree that the nomenclature regarding tests for HIV can be confusing.  The acronyms NAT and NAAT both stand for nucleic acid amplification tests. Each test is a PCR-type test in which the RNS of the HIV virus is chemically amplified to detect the presence of the virus in blood.  It is typically the test for HIV which becomes positive first following infection and is typically positive within two weeks of acquisition of infection.  These tests can be either qualitative or quantitative.  The quantitative test is used to determine the effectiveness of anti-HIV therapy.  For the purpose of diagnosis, either test if fine since one cannot be "a little bit infected" with HIV. 

Any NAAT, RNA PCR-type test would provide a definitive answer as to the presence or absence of infection at four weeks, particularly if combined with an combination HIV antigen./antibody test.  conversely, if all of these tests are negative at 4 weeks, one can be absolutely confident that they did not acquire HIV.

Finally, I will add, for the educational value, that we typically recommend against use of NAAT tests for HIV diagnosis for two reasons- first they have a somewhat higher rate of falsely positive test results than the combination antigen/antibody tests and secondly, they tend to be more costly than the other tests. 

I hope this information is helpful.  EWH
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38 months ago
Dr. Hook, Thank you for your detailed response.  So, for a nonclincal person, any RNA test combined with the duo are conclusive at 4 weeks it appears.  

As you probably saw from my earlier thread, Dr. Handsfield recommended against any testing for me from the "zero" risk exposure.  I kind of tabled it in my mind even past the 4 week mark and past the holiday until now which is 42 days today.  I think I want to put this to bed n my mind by getting tested this week.

Edward W. Hook M.D.
Edward W. Hook M.D.
38 months ago
If you choose to test, I am confident that the test will be negative   At the same time, I agree with Dr. Handsfield that there is no medical or scientific reason for testing. EWH
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38 months ago
For my final followup, what might be the percentage of false positives of the rna test and what tends to cause the false positives?

Thanks again  for your responses.
Edward W. Hook M.D.
Edward W. Hook M.D.
38 months ago
The cause of the false positives is, in part, a result of the chemistry which makes NAATs so sensitive.  There are not well described, specific types of people who have falsely positive tests.

Occasional false positive PCR/NAAT tests are well described but precise estimated are hard to come by and may vary depending n which testis being used.  In general, they occur less than 1% of the time, a figure which is more than 100 times higher than the false positive rate for combined HIV antigen/antibody tests.

I hope these comments are helpful.  As you know, in that this is my 3rd response, this thread will be closed in a few hours.  Take care.  EWH


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38 months ago

Dr. Hook,  Thanks for taking your time to share your knowledge with me.  I went ahead and tested this morning with RNA and Duo at Labcorp to clear my head of this (if all comes back negative as you and Dr. Handsfield believe they will.)

Thanks again.