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What Does Increased Index Values In The HIV 1 And 2 Antibody And P24 Combo Method Indicate?

Posted on Wed, 26 Mar 2014

Question: I had a possible hiv exposure 2 years ago. I got tested six times so far by hiv 1&2 antibody and p24 combo method. All the results came negative. But the index value shown in the report is consistently increasing. Index values are as under- March, 2012 - 0.12 XXXXXXX 2012 - 0.17 Feb, 2013 - 0.24 August, 2013 - 0.35 November, 2013 - 0.42 XXXXXXX 2014 - 0.69 This is to mention here that I have swollen lymph nodes in neck for 1.5 years. Recurrent fevers on every 4-5 days for 2 years. Rashes on the eye lids. My condition is deteriorating by every passing day. Immense pain in muscles and joints. Gastric problems, headaches, fatigue, malaise has become almost part of my life. A thick white cheese like coating on my tongue. My questions are- 1. why is the index value increading? it should have decreased at least one time. Does increasing value mean virus is present and replicating consistently? 2. Can window period extend upto or more than 2 years? What does index value mean and how is it determined? 3. Is it possible to have hiv and remain negative for two years?? 4. will I eventually turn positive after some time?? I would apprecite if my concerns are addressed by none other than an hiv expert.

Answered by Dr. Praveen G (47 minutes later)

Brief Answer: If index values are < 1,nothing to worry about HIV Detailed Answer: Hello, Welcome to Healthcare Magic, I have gone through history and understand your concern and the anxiety. 1.As you have done CMIA (Chemiluminiscent microparticle immunoassay) index for 6 times over a period of last 2 years following possible exposure and your concern is regarding increase in index value, don't worry as your result as come as negative after 180 days of possible exposure.It is 100% conclusive that your are negative for HIV 1/2 infection.These index values can really fluctuate. If you take test several times a day, your index value will fluctuate each time.As long as it is less than 1,you should not be worrying about these values. 2.Known window period for HIV is maximum of 180 days following possible exposure (Usually 3-6 months).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(<1) because of non specific antigen and antibody reactions. 3.No, HIV is a immunosupressive condition as your test for antibodies against HIV 1/2 is negative after the maximum window period you may not be having HIV infection. 4.Once antibodies are not produced against HIV there will not be any possibility of becoming HIV positive. Still if you have any doubts regarding your HIV status, repeat the test with different principle like P24 Antigen ELISA test and Antibody ELISA test. Hope I have answered all your queries, if you any further query feel free to post them. Thank you.

Above answer was peer-reviewed by : Dr. Vaishalee Punj

Follow up: Dr. Praveen G (25 hours later)

My specific point is why the index value did not decrease even a single time? what are the factors that may affect index value?? what are the factors that may cause false negative results?? Is it possible that a window period may extend upto 2 years? which are the other deseases/conditions that may mimic hiv? I would appreciate if u give specific reply, sir. thanx

Answered by Dr. Praveen G (1 hour later)

Brief Answer: CMIA Index Detailed Answer: Hello, It is my pleasure to answer you query, 1.The numerical differences have to do with the biochemistry of the test, not because a higher value specimen have anti-HIV antibody. 2.Exposures to different foreign antigens, proteins and infectious agents will produce various antibodies in the system, and the more likely that there will be several cross-reacting antibodies which will affects the index values. 3. Some of the conditions which produces false positive test are autoimmune diseases, recipient passive immunization, exposure to viral vaccines, presence of circulating immune complexes and Naturally occurring antibodies. 4.I have never seen a patient who is negative for test at 6 week after possible exposure and turn positive after 2 years. 5. Above mentioned autoimmune diseases can mimic like HIV, but it can be confirmed by ELISA antibody tests. Hope you are happy with the answer, still if you have any further query feel free to post them. Thank you.

Above answer was peer-reviewed by : Dr. Vaishalee Punj

Follow up: Dr. Praveen G (3 days later)

Hi sir, I also had a western blot test which says "No virus specific bands detected."

Answered by Dr. Praveen G (32 minutes later)

Brief Answer: Confirmed that you are not having HIV Detailed Answer: Hello, As I have told in the previous responses that you are not having HIV infection it is evident and confirmed by the western blot test. Now it is 100% conclusive that your are negative for HIV 1/2 infection. If you have any further query, please post them. Thank you.

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Above answer was peer-reviewed by : Dr. Yogesh D