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what does "p24 antigen 0.206 with referbn" indicate? - Online Doctor Chats

Date : 27-Feb-2014
User rating for this question
Very Good Posted in: HIV and AIDS
Answered by

General & Family Physician
Practicing since : 2004
Answered : 1777 Questions
User:Hi Doctor
Doctor:please proceed with your query
Doctor:are you there?
User:Hi Doctor I had sexual intercourse with a professional woman two months ago and used the condom. Before that around three months I had unprotected oral sex.
User:I got tested yesterday and got the following results
User:1) Hiv (1 and 2) negative
Doctor:please tell me the result
User:2) p24 antigen 0.206 with referbn
Doctor:all right
User:reference values negative below 0.9 and positive above 1.0 COI
Doctor:your test result is negative for HIV 1 and 2
User:I read a bit about these. What is the differnece between a lower level for p24 antigen and higher but below 0.9?
User:I mean could it be that my p24 level was higher but then dropped to 0.2 after two months. I read that p24 is more effective when done much earlier?
Doctor:There is no difference as such
Doctor:It is not possible this way that the level was higher and has dropped now
Doctor:Once the P24 is positive, it tends to raise rather than decreasing
Doctor:Compared to the other standard tests, P24 is more effective
User:thank you but what does the level exactly mean? why have two different not infected persons different levels of this antigen
Doctor:P24 is the core antigen
Doctor:The levels can vary depending on the stage
Doctor:viral load
Doctor:the period of infection
Doctor:the method of testing
Doctor:as long as the level is below the reference, the test is considered negative
Doctor:It can vary in the same person when done at different times, and at different labs
User:why have different people who are not infected different levels of this antigen
User:isn't it that this vore antigen is either not present and has value of 0 or is there?
Doctor:Ideally it should be 0
Doctor:However, the test per se would not detect 0 p24 antigen
User:I don't understand then any level above 0 means a little infection?
Doctor:a level of 0 means no infection
User:and any level above 0 means a little infection?
Doctor:it depends on different tests that is used to estimate P24 level
Doctor:it is not like
Doctor:For any test value above 0, it means a possibility of the infection that requires repeat testing
User:so should I do the test again?
Doctor:it is kind of a neutralization procedure
Doctor:using a minimum of 5 controls
Doctor:If your test is positive with these 5 controls, then repeat testing would be recommended
Doctor:If your test is negative, you do not need to repeat the test
User:but you said: "For any test value above 0, it means a possibility of the infection that requires repeat testing"
Doctor:Yes, you can repeat the test in 3 months again
Doctor:after 3 months of this P24 test date
Doctor:are you getting me?
User:I don't understand: you said 1) "If your test is negative, you do not need to repeat the test" and then 2) Yes, you can repeat the test in 3 months again
Doctor:let me explain it to you again
Doctor:May I know your age?
Doctor:What was the date of your last exposure?
User:two months ago
Doctor:What was the date of your P24 test?
Doctor:the date of unprotected sexual intercourse?
User:three months ago unprotected oral sex
Doctor:For any test, there would be the particular labs reference range
Doctor:Could you mail me the report?
User:yes, I can mail you the report
Doctor:p24 antigen 0.206 this is your report
User:its says p24 antigen 0.206
User:and the reference values are negative 0.9 COI
User:border case between 0.9 and 1.0
User:and positive above 1.0 COI
Doctor:all right
Doctor:your test is definitely negative
Doctor:that is what I was saying, when the test is being done, we use controls as well
User:and HIV (1 and 2) negative
Doctor:according to your P24 test, your value was 0.206 compared to the control value of 0.9
Doctor:This means your blood tested negative for P24
Doctor:If it were to be positive, it should have been well above 0.9
User:I'm really sorry to bother you but I still dont understand your earlier remark that "For any test value above 0, it means a possibility of the infection that requires repeat testing"
User:mine is above 0 it is 0.2
Doctor:The other two test HIV 1 and 2 are routine tests,
Doctor:See, the reference range for your test is 0.9
Doctor:your test value is 0.2
Doctor:Although this test report is negative, there can still be remote possibility of infection to be there
Doctor:Hence, it is recommended to repeat the test again now, and also to repeat the test after 3 months to be sure of the absence of disease
Doctor:Are you getting me now
Doctor:To allay your doubts, there is no harm in repeating the same P24 test
User:I did the test just yesterday?
Doctor:Even if you get the same result of 0.2,it is better to repeat the test after 3 months
Doctor:Yes that is right
Doctor:If you are worried about the test being faulty, you can repeat it again now
Doctor:else, wait for 3 months and repeat
Doctor:all right?
User:Just to make sure I get it:
Doctor:tell me
Doctor:are you there
User:is there a difference bewteen a 0.2 and 0 in terms of being infected when the refernce value is 0.9?
Doctor:there is no difference
Doctor:both 0 and 0.2 would mean the same
Doctor:is it clear now?
Doctor:meaning no infection
Doctor:hope you are getting it now
Doctor:only value more than 0.9 suggests presence of infection
User:but you said "For any test value above 0, it means a possibility of the infection that requires repeat testing" did you say that because you didnt know the reference value and assumed it was 0?
Doctor:there can be a remote possibility
Doctor:no test is 100% sure in diagnosing HIV
Doctor:Are you anxious to repeat the test again?
Doctor:If in doubt, you can go ahead and repeat it
User:yes I understand but what gets me confused is the 0.2 value
Doctor:It is possible to get this value based on the reference or controls that was used
Doctor:However, by all means your test is negative both for HIV1 and 2
User:and your remark thyat a level of 0 means no infection
Doctor:0 means no infection as well
User:3 months is a very long time to wait and a repeat test with thank you do you think I can can have sex without condoms with my wife and have a normal live wth my child
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