[Question #26] Help with HSV results

101 months ago

I just had a round of STD testing completed and am looking for some help verifying my HSV result.  The results are as follows: 

HSV IGM - 1.33 Positive (Did not breakdown 1 and 2) 

HSV 1 IGG - .15 Negative 
HSV 2 IGG - .07 Negative 

I've been tested for HSV IGG before, but never for IGM. My doctor always said that IGG was the better test and my results were always negative. I'm not sure why the IGM was ordered, I'm thinking my doctor did it by mistake. I've also read on here and other sites that the IGM test is useless and should never be used. Is that true? Based on my IGG negative results does that mean I do not have herpes? I haven't had sexual relations of any kind in about a year and half so I know the IGG result are valid, it's just the IGM result that is confusing. 

Thanks for the help! 
H. Hunter Handsfield, MD
101 months ago
Welcome to ASHA's Ask the Experts forum. Thanks for your question.

Your doctor is right: IgG is by far the better test for antibody to diagnose HSV infection. You can and should ignore the IgM result; it does not indicate you have an HSV infection.

In theory, the body produces immunoglobulin M (IgM) antibodies first and immunoglobuin G (IgG) antibodies later, and a test for IgM antibody may be positive before a test that detects IgG antibody.  IgM antibody is then supposed to go away, and in someone infected a long time previously, IgM antibody is absent but IgG persists.


That's the theory.  Unfortunately, it doesn't work well for HSV.  IgM antibody to HSV often doesn't precede IgG antibody, and IgM often persists for a long time. In addition, IgM testing is prone to give false positive results. Second, IgM tests are not type-specific, i.e. they don't accurately distinguish between HSV1 and HSV2 antibody. Your result has both these problems: it is false positive, and as the report says, even if truly positive, it can't tell which virus type is present. My guess is your doctor didn't actually request the IgM test. Many labs do it more or less automatically whenever HSV antibody testing is done. Why they keep doing an unreliable test is another story, but many labs simply aren't aware of the problems with the test; and IgM testing is very cheap but gets good pay-off from insurance companies, so the profit margin is high.

The bottom line is that you can disregard your apparently positive IgM test result. You don't have HSV (either type) and needn't worry any more about it.

I hope this has helped. Best wishes--  HHH, MD

101 months ago
Thank you so much! You've really helped put my mind at ease!
H. Hunter Handsfield, MD
101 months ago

Thanks for the thanks. I'm glad to have helped. I'll leave this question open for another day, in case another follow-up comment or question comes to mind. After that it will be closed to new comments. Take care and stay safe.
101 months ago
Thank you for your time. I actually do have one more question that I have always wondered about, but never knew if I could trust what I read on the Internet. Ever since I started getting tested for HSV my results have always fluctuated in numeric value. Is that normal? Would a true negative test have to be a 0.0 value? I've listed my previous results below for reference.

June 2009
HSV 1 IGG - 1.52 positive 
HSV 2 IGG - .19 negative 

January 2010
HSV 1 IGG - .1 negative 
HSV 2 IGG - .06 negative 

February 2012
HSV 1 IGG - <0.01 negative 
HSV 2 IGG - <0.01 negative 

June 2015
HSV 1 IGG - .15 negative 
HSV 2 IGG - .07 negative 

Also, as you can see my first HSV 1 IGG back in 2009 was what my doctor called a low positive and said that three other negative HSV 1 test confirm that it was actually a false positive test.  Would you agree with that and I don't have HSV - 1? Sorry for the bother, it's just that the testing can be somewhat confusing and like I said before you never really know what literature you can trust on the Internet.

Thanks again!!
H. Hunter Handsfield, MD
101 months ago
The numbers do indeed vary widely. Even the same specimen tested 10 times will give 10 different numbers. It's inherent in the biochemistry of the test. Your HSV2 value of 0.19 in 2009 doesn't mean you had a little bit of antibody or anything else different than the lower values in the other years. As long as the number is under the positive cut-off, it's a clean negative. And as you have seen, the test isn't perfect and gave an obvious false positive result for HSV1 in 2009. With the others definitely negative, you can take them as the truth.

My only other comment is your annual testing. Unless you get symptoms that suggest a new HSV infection, or are at particularly high risk, such as unprotected sex with large numbers of partners, or a regular partner known to have HSV2, testing is not something that would be recommended by herpes and STD experts. As you already saw once (2009), having a false positive result one of these days may be more likely than the chance of catching HSV. Just something to keep in mind as you consider whether and when to test again.