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What Does HIV Ag-Ab Test Indicating Reactive To HIV-1 P24 Indicate?

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Posted on Mon, 16 Oct 2017
Question: I am very concerned about some conflicting test results I received recently. On July 5 of this year, I took an Insti Rapid test which had a non-reactive result. However, the laboratory test of the same day blood specimen came back this way:

The HIV Ag-Ab test indicated reactive to Hiv-1 p24 antigen and non-reactive Hiv-1 Ab and Hiv-2 Ab. The NAAT (Nucleic Acedic Amplification Test) was non-reactive. Therefore, the analysis resulted in an HIV Negative result as HIV-1 RNA was not detected and no HIV antibodies were confirmed.

This week on September 18, I took another Insti Rapid test which indicated non-reactive again, which was about 11 weeks (75 days to be exact) since last Insti test. I'm currently waiting on the laboratory results, which I should get next week or the following.

I am very anxious as I wait on these lab results.
Roughly a week or less before I took the July 5 test, I had a one time encounter with another male and had protected sex. I let him perform anal sex with me. He wore a condom.

I am wondering how to handle these conflicting test results so far, given that the p24 antigen test was reactive and the other tests on July 5 blood sample were not AND the Insti test on September 18 was non-reactive.

Should I be bracing for the worst possible news of an positive result for HIV?

How accurate is the Insti test after 11-12 weeks.
doctor
Answered by Dr. Chobufo Ditah (4 hours later)
Brief Answer:
Most likely to be HIV negative!

Detailed Answer:
HI and thanks so much for this query.

I have reviewed this information fully.

1. With a negative antibody test about 6weeks after the potential exposure, there is no reason to expect that this test is unreliable or was done too soon. That of July 18 was clearly too soon and couldn’t have detected an infection if you were truly nfceted.

2. The positive antigene test back in July could suggest an infection. With a positive test, it raises genuine concerns and I will want to see what the next test shows. However, with the negative antibody test, I tend to think this would be more likely negative than positive.

In all, the chances are greatly reduced because of the negative antibody test but the test of July warrant patience before making conclusive statement at this time.

I hope this guides and helps. I wish you well. Feel free to follow up with me if need be.
Above answer was peer-reviewed by : Dr. Vaishalee Punj
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Follow up: Dr. Chobufo Ditah (18 hours later)
Thank you, Dr. Ditah.

Clarification in response to your response: I took the second Insti test this past week on SEPTEMBER 18, after the first one on JULY 5. So this second Insti test was taken almost 11 full weeks since the first one, not just six weeks as you previously stated. So it occurs to me that my second Insti test was roughly 12 weeks after the sexual encounter. This seems even more assuring! However, I did read somewhere that in some rare cases some persons don't develop the hiv antibodies that can be detected until past 3 months and as much as 6. Is this true? Is this outdated information in light of the tests like Insti which are more advanced in early detection compared to other tests of the past?

Overall, your response has been reassuring, but I can't help but feel a lot of concern about the initial "reactive"/positive antigen test result, as you've stated. I've read that false-positives are rare. Is this true? Are they uncommon?

I'm also resssured by the NAAT (RNA) result that they use in the current algorithm/testing procedures, but I'm thoroughly confused why the XXXXXXX would not detect the virus itself while the p24 antigen test detected the protein associated with the virus and, hence, resulted in a positive. It's perplexing. Also, it begs the question: Is the NAAT result of negative more reliable than the p24 antigen test result of positive?

Thank you, Dr. Ditah.





My concern has been
doctor
Answered by Dr. Chobufo Ditah (19 hours later)
Brief Answer:
I lean more towards a negative test and not a positive one!

Detailed Answer:
Hi,

It's difficult to make a definitive call with conflicting reports. However, looking at all the details, I will pick a negative result over a positive one in this case unless a definitive test come sup at some point later.

I understand your anxious state. I wish you well. Feel free to follow up with me when you get the final details.

I wish you well.
Above answer was peer-reviewed by : Dr. Prasad
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Answered by
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Dr. Chobufo Ditah

General & Family Physician

Practicing since :2009

Answered : 6320 Questions

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What Does HIV Ag-Ab Test Indicating Reactive To HIV-1 P24 Indicate?

Brief Answer: Most likely to be HIV negative! Detailed Answer: HI and thanks so much for this query. I have reviewed this information fully. 1. With a negative antibody test about 6weeks after the potential exposure, there is no reason to expect that this test is unreliable or was done too soon. That of July 18 was clearly too soon and couldn’t have detected an infection if you were truly nfceted. 2. The positive antigene test back in July could suggest an infection. With a positive test, it raises genuine concerns and I will want to see what the next test shows. However, with the negative antibody test, I tend to think this would be more likely negative than positive. In all, the chances are greatly reduced because of the negative antibody test but the test of July warrant patience before making conclusive statement at this time. I hope this guides and helps. I wish you well. Feel free to follow up with me if need be.