Positive antibody test, negative viral load--so why a genotype test?

[OpenSource]

Hi! As the title suggests, I recently had a positive antibody test, but my viral load test came back undetectable. Now my nurse says I need to go in to get a genotype test. Why is this so? My nurse had no clue. I would think I would just have to go in in 6 months to see if I have a sustained undetectable viral load (and if it ended up being detectable, THEN get the genotype test done). Thoughts?

Thank you!

[KimInTheForest]

Hi! As the title suggests, I recently had a positive antibody test, but my viral load test came back undetectable. Now my nurse says I need to go in to get a genotype test. Why is this so? My nurse had no clue. I would think I would just have to go in in 6 months to see if I have a sustained undetectable viral load (and if it ended up being detectable, THEN get the genotype test done). Thoughts?

Thank you!

I am not a doctor... but there was a time when the genotype test (qualitative PCR) was more sensitive and could detect a smaller quantity of virus than the viral load test (quantitative PCR). The genotype test couldn't count the virus, but it could detect a smaller amount. I don't know if they were done on different machines then or what. I thought in recent years that these two tests were being done at same time on same machine from same vial of blood. But maybe that is not true everywhere.

If you don't have to pay for the genotype test, and if your doctor has recommended it - why not? That would be my approach.

best,
kim

[Lynn K]

That is odd

If you have a not detected HCV RNA by PCR aka viral load there is no virus to test for so nothing to genotype. Were you treated for hep c? I ask because you used the word sustained undetectable and we normal use that to confirm treatment has worked and that we have a sustained viral response (SVR) to treatment once we stop taking meds.

From what I understand if you have had a positive antibody test the next step is to check for a viral load with the thest for the virus itself the HCV RNA by PCR test. If the test result for the virus is "not detected" you don't have hep c and no additional hep c testing is required. If the viral load is negative you don't have hep c there is no need to retest in 6 months the viral load test is definitive.

When I last had a genotype test done in 2014 it was a separate test it was not a part of my viral load test.

What kind of doctor is this? Are they familiar with treating hep c? Just to ask are you absolutely sure if was a test for the virus? Can you ask your doctor for clarification?

Good luck,
Lynn

[Lynn K]

I found this info from the CDC it has a flow chart for testing there is a not on the flow chart on how to proceeded after a negative viral load test

HCV antibody reactive, HCV RNA not detected
No current HCV infection
No further action required in most cases.
If distinction between true positivity and biologic false positivity for HCV antibody is
desired, and if sample is repeatedly reactive in the initial test, test with another
HCV antibody assay.
In certain situations§ follow up with HCV RNA testing and appropriate counseling.

http://www.cdc.gov/mmwr/pdf/wk/mm62e0507a2.pdf

But as Kim said if it doesn't cost anything sure why not but I am curious as to the rational for a genotype test with no detectable virus.

[OpenSource]

Hi, and thanks for the responses. I will definitely go ahead and do as my nurse suggests. For reference, I am a member of Kaiser Permanente (USA), and given how top-heavy the system is I would think this is their protocol. It just seems super weird and counterintuitive. I called again to confirm that I wasn't mishearing, and the nurse confirmed that they want me to do the genome test even though my viral load is undetectable.

To answer your question, Lynn, it was definitely a Hep C test. Also, I have never been treated for Hepatitis C, and I just meant I had an undetectable viral load (please forget the "sustained" part of my statement).

[Lynn K]

No worries about the sustained just threw me off because we here use it in a specific way.

Good luck but pretty sure you are good to go.

I guess it is their money so sure why not

[OpenSource]

I even wonder if they're doing this as a precaution because I have multiple sclerosis? I just posted a new question on the topic of autoimmune diseases and false positive antibody tests. Here's the link if anyone's interested in this topic: http://forums.hepmag.com/index.php?topic=3784.msg36617#msg36617

[Lynn K]

I guess the only way to know their reasoning would be to ask

I personally would be curious to know

[OpenSource]

Sure, I'll post here when I can speak to someone who knows. 

[BillT]

Hi Opensource,
                     As with everyone else I'm not a Dr either.One thing that I have run across in all my reading is the fact that some people have been exposed to the HCV and their immune system has been able to fight it off so they show positive for the antibodies but aren't infected.As Kim said,why not test to be sure.Maybe you are one of the lucky one's,but the only way to tell is by testing.Let us know how it turns out for you.