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Reliability of P24 DUO test
Hi Doctor
Just over a month ago I had unprotected vaginal and oral sex with a girl of unknown sexual history.
I travelled all the way to London from the North west of England yesterday for a duo test as no one in the north does them (a bloody long way). The result came out and said HIV 1 & 2 antibodies / P24 Ag screen negative.
On all the forums and web pages I have read they say the P24 test in conclusive and if you are pos and the P24 test doesn't pick it up the antibody test definitely will.
The consultant said the test wasn't 100% and recommended retesting at 3 months. The whole idea of me paying over
Just over a month ago I had unprotected vaginal and oral sex with a girl of unknown sexual history.
I travelled all the way to London from the North west of England yesterday for a duo test as no one in the north does them (a bloody long way). The result came out and said HIV 1 & 2 antibodies / P24 Ag screen negative.
On all the forums and web pages I have read they say the P24 test in conclusive and if you are pos and the P24 test doesn't pick it up the antibody test definitely will.
The consultant said the test wasn't 100% and recommended retesting at 3 months. The whole idea of me paying over
What they called the 2nd window is just a transient period ( matter of few days,less than a week) that can happen in the seroconversion when the p24 is disapearing and the hiv anti-bodies start to come out. I read a report where that happened in a study of 4th. generation tests. If I recall right, one person was positive ( caught p24) and 3 days later he was negative (no antibody or p24 detectable). A very few days later he became positive for good. They also said this is very rare and absoulutely a transient kind of thing. It makes no difference in a 3-month window period.
The Doc has been a great help on here for me. For US doc's to be quoting 4 weeks and UK doc's 3 months is potentially life destroying.
If anyone in the UK is considering a P24 DUO test do it for peace of mind. I had to travel from Liverpool to London but was relieved at my result.
P.S. Doctor, is it true if the your past the P24 detection period will the standard antibody test show the true result? I have read differing results and am curious.
Many Thanks
If anyone in the UK is considering a P24 DUO test do it for peace of mind. I had to travel from Liverpool to London but was relieved at my result.
P.S. Doctor, is it true if the your past the P24 detection period will the standard antibody test show the true result? I have read differing results and am curious.
Many Thanks
The Doc has been a great help on here for me. For US doc's to be quoting 4 weeks and UK doc's 3 months is potentially life destroying.
If anyone in the UK is considering a P24 DUO test do it for peace of mind. I had to travel from Liverpool to London but was relieved at my result.
P.S. Doctor, is it true if the your past the P24 detection period will the standard antibody test show the true result? I have read differing results and am curious.
Many Thanks
If anyone in the UK is considering a P24 DUO test do it for peace of mind. I had to travel from Liverpool to London but was relieved at my result.
P.S. Doctor, is it true if the your past the P24 detection period will the standard antibody test show the true result? I have read differing results and am curious.
Many Thanks
Cany you clarify 2nd window period?
Do you mean as the antigen falls and the antibody increases that type of thing is the window period is still 3 months for this types of test is it not?
Dorff
Do you mean as the antigen falls and the antibody increases that type of thing is the window period is still 3 months for this types of test is it not?
Dorff
The p24 Antigen Test
The p24 antigen test identifies actual HIV viral particles in blood (p24 is a protein specific for HIV). However, the p24 antigen test is generally only positive from about one week to 3 - 4 weeks after infection with HIV. The p24 protein cannot be detected until about a week after infection with HIV, because it generally takes that long for the virus to become established and multiply to sufficient numbers that they can be detected. The p24 antigens then become undetectable again after sufficient antibodies to HIV have been produced, because they bind to the P-24 protein and eliminate it from the blood. Once antibodies are produced, the p24 test will register negative even in people who are infected with HIV. Of course, at that point the regular HIV antibody test will then be positive.
The p24 antigen test has very limited value in diagnosing HIV infection. It has been used in HIV research and, since 1996, has been used as an additional screening test in blood banks to help reduce the window period and reduce the possibility of HIV infected blood being used in transfusions.
Most people will not benefit from having a p24 antigen test. People who have engaged in behaviors that may have put them at increased risk of infection with HIV should not give blood in order to be tested by the blood bank.
Viral load / PCR Testing
Viral load testing is the direct measurement of the amount of HIV present in the blood. Several different tests identify and measure the genetic material resulting from virus infection, either RNA or DNA. These tests are also called nucleic acid tests. The laboratory procedure used to test for the genetic material of HIV is called the Polymerase Chain Reaction (PCR) test. PCR viral load testing is usually done to allow doctors to track how active HIV is in a person
The p24 antigen test identifies actual HIV viral particles in blood (p24 is a protein specific for HIV). However, the p24 antigen test is generally only positive from about one week to 3 - 4 weeks after infection with HIV. The p24 protein cannot be detected until about a week after infection with HIV, because it generally takes that long for the virus to become established and multiply to sufficient numbers that they can be detected. The p24 antigens then become undetectable again after sufficient antibodies to HIV have been produced, because they bind to the P-24 protein and eliminate it from the blood. Once antibodies are produced, the p24 test will register negative even in people who are infected with HIV. Of course, at that point the regular HIV antibody test will then be positive.
The p24 antigen test has very limited value in diagnosing HIV infection. It has been used in HIV research and, since 1996, has been used as an additional screening test in blood banks to help reduce the window period and reduce the possibility of HIV infected blood being used in transfusions.
Most people will not benefit from having a p24 antigen test. People who have engaged in behaviors that may have put them at increased risk of infection with HIV should not give blood in order to be tested by the blood bank.
Viral load / PCR Testing
Viral load testing is the direct measurement of the amount of HIV present in the blood. Several different tests identify and measure the genetic material resulting from virus infection, either RNA or DNA. These tests are also called nucleic acid tests. The laboratory procedure used to test for the genetic material of HIV is called the Polymerase Chain Reaction (PCR) test. PCR viral load testing is usually done to allow doctors to track how active HIV is in a person
I appreciate all your input and thst of the doctors but does anyone know how reliable the P24 test is after a 4 week period?
Sorry to to be a pain in the *** but the consultant I saw was the most negative person I have ever me. I was expecting him to say "4 week dou test neg, yes your OK".
Thanks again guys & gals
Sorry to to be a pain in the *** but the consultant I saw was the most negative person I have ever me. I was expecting him to say "4 week dou test neg, yes your OK".
Thanks again guys & gals
Hi
I think that were terrified because society still stigmatizes this disease, it's not just the worry of having HIV, its the paranoid thoughts about losing control of your life, losing your job, losing your partner, losing quality of life and the images that still stick with us from the 80's of dying alone.
I'm feel just the same as you, i have actually tested beyond the 3 month mark but still worried.
I tested at a GUM Clinic in Ashton-U-Lyne, you should be able to find the address and contact no online.
I remember seeing my paper results and there were 3 categories P24, HIV1 and HIV2.
I thought that most if not all GUM clinics would have used the same tests, i think that they are sent out to 3rd party labs but not 100% sure.
I think that when you speak to someone at any clinic it's usually the receptionist and only the nurses or health adviser would specifically know what type of test's they do with any specifics.
Wishing you all the best......dorff
I think that were terrified because society still stigmatizes this disease, it's not just the worry of having HIV, its the paranoid thoughts about losing control of your life, losing your job, losing your partner, losing quality of life and the images that still stick with us from the 80's of dying alone.
I'm feel just the same as you, i have actually tested beyond the 3 month mark but still worried.
I tested at a GUM Clinic in Ashton-U-Lyne, you should be able to find the address and contact no online.
I remember seeing my paper results and there were 3 categories P24, HIV1 and HIV2.
I thought that most if not all GUM clinics would have used the same tests, i think that they are sent out to 3rd party labs but not 100% sure.
I think that when you speak to someone at any clinic it's usually the receptionist and only the nurses or health adviser would specifically know what type of test's they do with any specifics.
Wishing you all the best......dorff
Hi Mate
Where in the NW did you get ur duo test done, everyone I rang said they only did the standard antibody test including the Liverpool royal and the the Manchester main hospital.
Cheers mate
P.S. Why are we all so obsessed with HIV when we all have a 1 in 3 chance of cancer? This baffles me but doesn't solve my problem
Where in the NW did you get ur duo test done, everyone I rang said they only did the standard antibody test including the Liverpool royal and the the Manchester main hospital.
Cheers mate
P.S. Why are we all so obsessed with HIV when we all have a 1 in 3 chance of cancer? This baffles me but doesn't solve my problem
I think the test they more often use in England is the Abbott Axsym Meia Combo Ag-Ab (antigeno, antibody). This test ranked highly in all sites I read about it. (Yet, it is not used in the USA). However, there may be a slight problem with a 4th. generation test. In some studies, they have reported rare cases of a 2nd window period. It happens when the antigen p24 is no longer present and the antibodies just start to apear and may not be detectable either. Just transiently. But for sure there is not the case of yours.
hey doc what do you think of 10.5 weeks in the calucation, hey steve dont worry i have been there, this doctor has been in the business for 20 years, think of the best, and also do things you normally enjoy to get this out of your mind. peace
Hi Steve.
I live in the Northwest of th UK, i have had my HIV tests at a local GUM clinic and they were P24 antigen and HIV 1 and 2 Antibody tests.
Perhaps if you decide to test again it might be worth giving your local GUM clinic a call as they would probably perform the same test.
Hope this helps, Dorff
I live in the Northwest of th UK, i have had my HIV tests at a local GUM clinic and they were P24 antigen and HIV 1 and 2 Antibody tests.
Perhaps if you decide to test again it might be worth giving your local GUM clinic a call as they would probably perform the same test.
Hope this helps, Dorff
MEDICAL PROFESSIONAL
You probably didn't need testing at all unless you had specific reasson to believe your partner was infected (e.g., known HIV positive, injection drug user, etc). You certainly don't need more testing; your provider is being hyper-conservative. My advice has always been that decisions about the need for testing at various intervals does not depend entirely on the theoretical window period, which indeed can be as long as 3 months--but only very rarely. It also depends on the likelihood of infection.
Assume a 10% chance your partner had HIV. (That's probably much too high; even 1% probably is too high. But we'll stick with 10% for argument.) Infection transmission risk maximum 1 in 1000; actual statistics suggest 1 in 2000. Chance of having HIV despite negative duo test at 4 weeks, probably 1 in 1000, but let's again be conservative and assume 1% (1 in 100). The absolute maximum chance you have HIV at this point is 0.1 x 0.001 x 0.01 = 0.000001, or 1 in a million. If you plug in more realistic estimates, the actual chance is probably closer to 1 in 10 million or even 1 in 100 mil.
In other words, forget it. You don't have HIV. I think your original inconvenience and cost was pretty ridiculous and don't recommend you repeat it!
Good luck-- HHH, MD
Assume a 10% chance your partner had HIV. (That's probably much too high; even 1% probably is too high. But we'll stick with 10% for argument.) Infection transmission risk maximum 1 in 1000; actual statistics suggest 1 in 2000. Chance of having HIV despite negative duo test at 4 weeks, probably 1 in 1000, but let's again be conservative and assume 1% (1 in 100). The absolute maximum chance you have HIV at this point is 0.1 x 0.001 x 0.01 = 0.000001, or 1 in a million. If you plug in more realistic estimates, the actual chance is probably closer to 1 in 10 million or even 1 in 100 mil.
In other words, forget it. You don't have HIV. I think your original inconvenience and cost was pretty ridiculous and don't recommend you repeat it!
Good luck-- HHH, MD
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