What does "borderline between 0.9 and 1.0 and positive above 1.0" mean?

Posted on Thu, 6 Mar 2014

Question: Hi Dr XXXXXXX I had sexual intercourse with a professional woman two months ago and used the condom. And around three months I had unprotected oral sex with another professional woman. I got tested yesterday and got the following results 1) Hiv anticore (1 and 2) negative 2) p24 Antigen: 0.206 with reference values negative below 0.9, borderline between 0.9 and 1.0 and positive above 1.0 COI your test result is negative for HIV 1 and 2 I understand that these results are negative. But I have the following questions would really appreciate detailed answers if possible. What does a numerical level above 0 but below 0.9 really mean? Does it mean a low level of antigen since it is above 0 but below 0.9? 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? Or could the level increase. I read that this level has to do with measurement and shouldn't be taken into account. That it is kind of a neutralization procedure and as long as the level is below the reference, the test is considered negative. But why are there different levels for different people? Why have two different non-infected persons different levels of this antigen and are both above zero? Isn't it that this core antigen is either not present and has value of 0 or it is there and has a numerical value greater than zero? And yesterday during a chat with a doctor here I was told that "For any test value above 0, it means a possibility of the infection that requires repeat testing" which got me really confused. Could you please help me out?

Answered by Dr. Praveen G (16 hours later)

Brief Answer: Criteria for test reading in HIV Detailed Answer: Hello, It is my pleasure and privilege to answer your query. Your question is quite elaborate and informative one. Clarification of doubts regarding your query requires some microbiological and molecular knowledge. 1.In any person we may get numerical values of more than 1, because test which they have done is a qualitative one.Cutoff values is calculated based on values in hundreds of serum samples from uninfected persons. Even normal person may have value more than 0 and less than cutoff value because of non specific antigen and antibody reactions. 2.Dropped levels of P 24 is not possible in present case, because test is done within documented window period of 3 months. Antigen level may fall after seroconversion because of formation of antigen and antibody complex. P24 antigen is a early marker of infection as it can be detected as early as 3 weeks after possible exposure.Levels may increase until serconversion. 3.If the test is negative, different levels in different persons may be because of non specific antigen antibody reaction in the individuals. 4.Non infected persons will have different levels of antigen mainly because of non specific antigen antibody reaction and the antibody used to detect the P24 antigen (Horse or Goat) in the test.We cannot correlate numerical values with antigen levels as test done is a qualitative one and not the quantitative one. 5.Still if you any doubts, repeat the test with different principle like P24 Ag ELISA and Ab ELISA. Antibody ELISA can be repeated after 3 months and confirm that if it comes negative nothing to worry, because it is suggestive of not having any HIV virus or antibodies against antibody. Hope I had cleared majority of doubts and i know still you have got doubts, because some of them require molecular understanding. I have tried my level best to answer your query. Thank you.

Above answer was peer-reviewed by : Dr. Prasad

Follow up: Dr. Praveen G (47 minutes later)

Hi Dr XXXXXXX thank you very much for the detailed answer. Given the above would you recommend taking further tests? Can I have unprotected sex with my wife and continue life with my family as usual?Thank you

Answered by Dr. Praveen G (1 hour later)

Brief Answer: Yes, carry on with your life... Detailed Answer: Hello, It is my pleasure that I am able convey the information regarding HIV testing and its interpretation. As your tests P24 Antigen testing is negative and HIV 1/2 is negative after 3 months of possible exposure, it suggest me that you are not having HIV infection. As your results after the window period of 90 days is negative, still it confirms me that, 100% you are not having HIV infection. If your partner is not having any infection, definitely you can have unprotected sex and the continue your life happily. I wish you happy and prosperous life ahead. I am pleased to answer if you have got any query. Thank you.

Above answer was peer-reviewed by : Dr. Prasad

Follow up: Dr. Praveen G (12 minutes later)

Thank you for the reply Doctor XXXXXXX Just to clarify, I had two possible exposures: 1) Around 80 days ago 2) Around two months ago. I had the tests done yesterday. Would you recommend taking further tests?

Answered by Dr. Praveen G (10 minutes later)

Brief Answer: HIV Testing Detailed Answer: Hello, If you had any possible exposure on 60 days and 80 days and you done the test yesterday, theP24 antigen and HIV 1/2 tests were negative. P24 antigen is only useful in the immediate short term i.e. 2-4 weeks after infection. They are sensitive and effective and used only in conjunction with other testing. I would advise you to test for HIV 1/2 at the end of 90 days.sure it will come negative, but I don't want to take risk with my patients. If it comes negative all your doubts will be cleared and you are 100% HIV infection free. Still any doubts I am happy to clear them and want to see smile on you. Thank you

Above answer was peer-reviewed by : Dr. Shanthi.E