High Number for IgM test

[seeker75]

Let me preface my question by saying that I have read many topics on here and am aware of the inaccuracy of the IgM test for herpes.  However I read in a response to one of the posts that a higher result may give a greater likelihood of a "true" positive.  That having been said, a couple of weeks ago my girlfriend of about 10 weeks and I were in the process of relations.  She happened to be wearing underwear that was mesh with lace while I was naked.  She was on top of me and grinding on my penis and it was actually rather painful.  Not wanting to "spoil the moment", I let this go on for a bit until it was rather excruciating and I asked her to stop.  We had intercourse (which we have been doing a few times a week over the last 10 weeks) and it was not painful or anything.  A couple of days later I noticed a couple of bumps on the shaft of my penis that were right in the area where she had been grinding.  One had a small scab but the other did not.  I got freaked out at first but then after doing a lot of reading on the interned determined that they must be abrasions from the grinding.  The were not painful or itchy and I would have never known they were there without visual inspection.  I also did not suffer from any of the herpes symptoms that I have read about.  Well, my paranoia got the better of me and I got tested by LabCorp for Herpes.  Both IgG specific tests came back negative but the IgM test came back with a 3.08.  My girlfriend was suspected to have cervical cancer about a year and a half ago and gets tested regularly with no positive results to date.  My last sexual encounter prior to my current monogamous relationship was in mid October, after which I was tested and came back negative for HIV, Herpes, Gonorhea, Chlamydia and Syphillis.  After my long winded story, I come back to the question, does a higher value on an IgM test represent a greater possibility of a true "positive", or is it absolutely irrelevant based on the inaccuracy of the test? Thnx

[seeker75]

Thanks HHH,

It actually wasn't you who made the comment about a higher number in the IgM test indicating a higher possibility of a true positive, but a response comment from another member.  The comment inferred that number in the low 1's was most likely a false positive while a 3+ indicated a greater chance of a true positive.  As I don't know the medical background of the other posters on here I wanted to post the question to you directly.  Thanks for your help, I know that everyone here appreciates you!!

J

[H. Hunter Handsfield, M.D.]

To my recollection, I never said that "...a higher [IgM] result may give a greater likelihood of a true positive."  That is true for type-specific IgG testing, but I do not know that it is true for IgM.  Maybe, maybe not.

I am ignoring the unnecessarily detailed information about the nature of the sexual exposures you describe.  It is theoretically possible that the IgM result legitimately indicates new infection and that the IgG test will later turn positive.  However, if the type-specific IgG test was done 12 or more weeks after your last possible exposure, the results reliably indicate you did not acquire HSV of either type.  The strength of the IgM result doesn't matter.  Further, you cannot get useful information by side-to-side comparison of the IgG and IgM numerical results.  They reflect totally different test methods and the numbers don't measure the same thing.

Bottom line:  Since you describe no symptoms that suggest herpes, if the type-specific IgG test was done 12 or more weeks after your last possible exposure, you can be confident you don't have HSV.

I hope this helps.  Best wishes---  HHH, MD