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Time frame P24 Antigen to antibody
Hello Doctors,
This is a question that I am sure many reviewers are curious to have your expertise on, and one in which I am confused about. What is time frame currently associated between with time P24 antigen becomes detectable and time in which antibodies are detectable?
I have seen recent studies that indicate a range of between 4 and 15 days (with average of 7 days).
The reason I am curious about this is both of you (Dr. Handsfield & Dr. Hook) agree that a Duo test is definitive at 28 days (4 weeks), and an antibody test alone is definitive at 8 weeks.
I am looking for some clarification as to what this time frame between is in your opinions. If this time frame is indeed an average of 7 days, it would make sense that the antibody test should be definitive around 5 weeks.
If the time frame is around 15 days at longest, then this would put antibody definitive around 6 weeks.
This is why I can't understand why 28 days is definitive for Duo. I have read on many informative cites for the official duo/Combo testing cites that the tests are around 95% definitive at 28 days.
This is confusing to me as I do not understand the gap in between the 2 stated time frames (4 weeks and 8 weeks).
So...
1) What is your opinion of time frame between P24 and Antibody.
2) Why is your opinion 100% definitive at 28 days for Duo instead of the 95% stated by manufacturers.
3)Please explain the thought process for 4 weeks Duo, and 8 week Antibody.
Thanks so much for your clarification of this for me.
This is a question that I am sure many reviewers are curious to have your expertise on, and one in which I am confused about. What is time frame currently associated between with time P24 antigen becomes detectable and time in which antibodies are detectable?
I have seen recent studies that indicate a range of between 4 and 15 days (with average of 7 days).
The reason I am curious about this is both of you (Dr. Handsfield & Dr. Hook) agree that a Duo test is definitive at 28 days (4 weeks), and an antibody test alone is definitive at 8 weeks.
I am looking for some clarification as to what this time frame between is in your opinions. If this time frame is indeed an average of 7 days, it would make sense that the antibody test should be definitive around 5 weeks.
If the time frame is around 15 days at longest, then this would put antibody definitive around 6 weeks.
This is why I can't understand why 28 days is definitive for Duo. I have read on many informative cites for the official duo/Combo testing cites that the tests are around 95% definitive at 28 days.
This is confusing to me as I do not understand the gap in between the 2 stated time frames (4 weeks and 8 weeks).
So...
1) What is your opinion of time frame between P24 and Antibody.
2) Why is your opinion 100% definitive at 28 days for Duo instead of the 95% stated by manufacturers.
3)Please explain the thought process for 4 weeks Duo, and 8 week Antibody.
Thanks so much for your clarification of this for me.
MEDICAL PROFESSIONAL
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MEDICAL PROFESSIONAL
Correct. Best wishes.
Thanks for this Dr. H. I have a clear understanding now. I went for another test yesterday at 10 weeks. Duo negative. Thinking this is confirmation that no further test is necessary.
Thanks again.
Thanks again.
MEDICAL PROFESSIONAL
Welcome back to the forum. But I'm sorry to see you're having such trouble with this.
There is a basic flaw in your understanding that I think explains the problem. The times to positive antigen and antibody are quite variable. Measurable p24 antigen can appear as soon as 5 days or not until 10 or maybe even 15 days, then disappears over the next couple of weeks. Measurable antibody can appear as soon as 10 days but maybe not until 6 weeks, but once present, is there forever.
Those figures would seem to allow for gaps neither antigen nor antibody are present. What you're missing, however, is that these events are not independent. It is the antibody that clears p24 out of the blood. In other words, the p24 cannot become negative until at least several days (typically a couple of weeks) after antibody appears. Therefore, EVERYBODY with HIV infection of duration of 4 weeks or more ALWAYS has detectable p24, antibody, or both.
Indeed, with most of the duo tests, the result doesn't tell which component actually was positive, because it doesn't matter. If the test is negative, both antibody and antigen are absent. If positive, one or the other is present (and maybe both).
So do your best to move on, as Dr. Hook described. I would also suggest you stop searching the internet about this sort of stuff. Accept the evidence and the reasoned, science-based reassurance Dr. Hook gave you, and move on with your life.
Best wishes-- HHH, MD
There is a basic flaw in your understanding that I think explains the problem. The times to positive antigen and antibody are quite variable. Measurable p24 antigen can appear as soon as 5 days or not until 10 or maybe even 15 days, then disappears over the next couple of weeks. Measurable antibody can appear as soon as 10 days but maybe not until 6 weeks, but once present, is there forever.
Those figures would seem to allow for gaps neither antigen nor antibody are present. What you're missing, however, is that these events are not independent. It is the antibody that clears p24 out of the blood. In other words, the p24 cannot become negative until at least several days (typically a couple of weeks) after antibody appears. Therefore, EVERYBODY with HIV infection of duration of 4 weeks or more ALWAYS has detectable p24, antibody, or both.
Indeed, with most of the duo tests, the result doesn't tell which component actually was positive, because it doesn't matter. If the test is negative, both antibody and antigen are absent. If positive, one or the other is present (and maybe both).
So do your best to move on, as Dr. Hook described. I would also suggest you stop searching the internet about this sort of stuff. Accept the evidence and the reasoned, science-based reassurance Dr. Hook gave you, and move on with your life.
Best wishes-- HHH, MD
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