What do changes in Igg index mean?

Hello,

First, thank you for your help on this issue -- I've researched HSV online and offline thoroughly, but this website has surpassed other resources by far. As for me, I have 3 over-arching questions...

1. I still cannot find a clear explanation of why there are changes in the IgG index (i.e., the number given to represent HSV 1/2) from one test to another. I believe I read somewhere that it does NOT represent the severity of HSV and I read somewhere else that the number changes because it depends on some sort of statistic in the population. I've also read advice for people to wait one month or four months (depending on the source) before they get tested again, but that advice was not followed by a reason why. Is this because the statistic in the population may change from month-to-month?

If it helps to use my results as an example, my HSV2 IgG was 3.49 on a HerpeSelect ELISA test performed by Physicians Laboratories. I got tested about 1.5 weeks later in the hopes of finding that the first result was a lab error, so I went to a different place that used Quest Diagnostics and the HSV2 IgG was 3.81. If the index changed because I used a different test or lab, I would still appreciate an explanation for why the index would change from one test to another even if I used the same test and lab.

2. My second question concerns the type of test that I had the second time. On the test results sheet, the name of the test read as "HSV 1/2 IGG, HERPESELECT" -- the "Requisition" was "9978078", in case that helps. I read that there are different types of HerpeSelect tests so I called the only number I could find (a 1800 number for quest client services) to find out which one it was. I was only told that it was a HSV 1/2 IgG HerpeSelect Immunoassay. Is that the same as the ELISA test or is that the immunoblot or some other test? The results for the second test were only 1/2 a page long, much less detailed than the results for the first test which specified that it was an ELISA (which were 2.5 pages long).

3. The first test showed that my HSV 1/2 Combined AB, IgG was > 22.40. How could the combined index IgG be so much higher than the combined index for IgM, which was only .36? According to the IgM test, the .36 means "negative- No significant level of detectable HSV IgM antibody".

Also, my HSV1 IgG was 8.49. If the HSV2 IgG is 3.49, what accounts for the remaining 10.5 of the 22.40?  

Is any of this cause for getting a confirmatory test, such as the Western Blot?



Just to add, I have never experienced symptoms so I only have these antibody tests to go on. The slight differences between the two tests are frustrating because I read that the cut off itself to diagnose HSV2 is controversial and it may be less valid for low-risk persons. I also read that having HSV1 can increase the likelihood of a false positive HSV2 test result.

Thank you for any clarification when time permits (I know I asked for a lot of info)

[gracefromHHP]

1- you can get the same exact testing done at the same lab on the same day and get differing results. your results are both still positive. they really aren't all that different.

as to why to wait to test - about 1/2 of folks will test + at the 2-3 weeks post infection point but some folks take as long as 6 months to seroconvert. we recommend the 3-4 month mark because it catches the vast majority of folks who are actually positive during that time frame.  

2- you had the right test done. no worries.


3 - you are trying to compare apples to oranges. You absolutely can not try to compare the results of the combined test to the specific tests. they are totally different tests and can't be directed compared in the way you are trying to compare them.


you've never had symptoms and your results are still in the false positive range so it's worthwhile at this point to pursue a herpes WB to confirm your hsv2 status.

grace