[Question #6685] IGMs

12 months ago
Dear Dr. HHH,

I have read many posts saying the HSV IGM is unreliable however I got a recent positive score 1.99 and then  two days later 1.64 from a different lab and then I took one with IGM 1 and IGM 2 seperately from a third lab and that came back negative. All my HSV IGG scores both specific and non specific came back negative upto 9 weeks post exposure. The girl I was with tested and she came out HSV1 IGG positive. 

So my question is as follows: 

1. I was also diagnosed with Chlamydia - IGG was positive yet hers was not. I also had dengue recently about 2 months before the exposure. And I think I also got a fungal from her. 

You have said in some of your videos that false HSV IGMs can be due to the physical chemistry of the test and possibly due to other infections. Im just wondering if it is possible for dengue IGM or Chlamydia to cause the IGM to become a low positive as it seems you have a lot of knowledge on this subject. Do let me know your thoughts. 

Thanks for your time.

Best Regards,



12 months ago
The reason I ask is that 2 years ago I was tested for herpes and both my IGG and IGM came back negative. Also on this encounter I did not have a typical breakout either orally or on the genitals although I did have a bad penile rash that looked like balanitis and I had a two apthos ulcers/sores in the mouth (which could be due to stress, although I am not sure). I did not get a fever or anything other systemic symptoms either like body aches etc. And I also started doxycycline 100 mg with lacto acid bacillus for two weeks and took valcivir 500mg twice daily for 3 weeks. All other tests came back negative including HIV and the partner retested again in 7 weeks for HIV which came back negative.
Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
12 months ago
I'm confused here - you were diagnosed as having chlamydia but a blood test????  That is completely not the appropriate test - for men it should be a urine test and for women, either urine or swab from the vagina, optimally. 
The IgM has terrible issues with false positives - in my practice, 80-90% of positive IgM tests are NEVER confirmed with a positive IgG test and that's what you want to know.  However, you taking antiviral medicine can change the accuracy of the IgG test so if you do test again, consider staying off of antivirals.  If you do happen to be positive, and the test isn't picking it up because you took three weeks of antivirals, coming off medicine if going to make any partners more susceptible. 

Terri
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12 months ago
Hi thanks Terri for your response. Actually my question is a bit different. I wanted to understand what are the reasons for a false positive in the case of someone who has before the incident not had HSV 1 or 2 and therefore issues of cross reaction in this circumstance is not there (assuming I have not been infected).

I want to know if Chlamydia or fungal or dengue can cause a false IGM positive. This question may be out of the scope but thought I would ask. 

The reason I ask is because I did not have any real oral symptoms and neither did I have any real penile symptoms. My Dermatologist firmly says I don't have it and says that if my IGM was real, my IGG should have become positive by now since I have no history of previous antibodies to HSV.  I was tested two years ago for HSV and was negative on both IGG and IGM. 

Assuming Chlamydia diagnosis is accurate because my blood work showed IGG and IGM negative after taking the doxy, my theory is that maybe my hsv IGM went positive because of Rhuematoid Factor as Chlamydia is known to cause Reactive Arthritis. I have been having 6 months of unexplained severe joint pain in my left hip & lower back pain and I am an athlete so I thought it was because I had overdone it. But after taking the doxy my pain has also substancially subsided. The other reasons could be because of dengue which is a viral or the fungal which created antibodies which cross reacted to the HSV antigen. 

I will repeat my tests in 12 and 16 weeks. It just seems unlikely that HSV 1 IGG will not show up on my test yet it is showing up on my partner's test. And the Doctor here says antiviral will not change the IGG production and he says I can test in 12 to 16 weeks for a peace of mind. 

I'm just trying to close the loop on the IGM test which I know is very inaccurate. The Doctor does not know why IGMs can be false except he mentioned that it is 70% specific and 30% non specific. I just want to know potentially why this was the case. Perhaps it could also be something else like Mono that I have not tested or but my Doctor says again where are my symptoms for Mono as in fever etcetera should be evident.

Thanks for your time. 




Terri Warren, RN, Nurse Practitioner
Terri Warren, RN, Nurse Practitioner
11 months ago
Chlamydia is not to be diagnosed by blood antibody test but it's in the past and you feel you are better so case closed on that.
The IgM can be positive for a number of reasons as it is very specific to herpes - other viruses that you might have had in the past and don't even recall can trip this test.  We don't exactly what other infections might cause a false positive on this extremely poor test which the CDC says never should be used.
I would disagree strongly with your doctor who says that antiviral medicine, taken on a regular basis immediately after the first infection, cannot impact the IgG test.  We absolutely know that it can and the University of Washington that runs the western blot warns against this problem.  I had a patient who was diagnosed positive by swab test, chose to go on suppression for nine months but never seroconverted to a positive IgG test during that time.  She did not have a recurrence during that time and came to wonder if the swab was correct so she had an IgG done.  Negative.  I pulled her off suppression and she seroconverted to a positive IgG test within one month.  The function of antiviral medicine is to stop viral replication.  If it is working effectively and prevents viral replication, the immune system cannot see the virus because it isn't replicating and so antibody will not be made.  Does that make sense?

terri
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