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Re:New Guy wants to know if he can do one of those wooooohoooot things?
Jul 14, 2008

Dr. Bob, Dr. Bob thank you so much for answering my question! I cannot thank you enough! I'm so sorry but I left out a crucial question, I was so mad when I realized that I left it out.

In regards to the Hepatitis C Quantasure Plus test. I just wanted to know if that was a good test? And are you 100% sure that since it said <10 Iu/mL that I am ok? I was weirded out when I read that the FDA hadn't approved of the HCV Quantasure Plus (serial) test. I trust your professional expertise but can you educate me a little on the accuracy of the test? Also, do alot of people have viral loads less than <10? Thanks so much! I am gonna make a donation, my friend has your foundation's address.

Response from Dr. Frascino

Hello,

First off, I should mention I am not a hepatologist (liver specialist), but rather an HIV/AIDS specialist. We do have an entire expert forum devoted to hepatitis and HIV coinfection. You might want to check with experts in that forum as well.

What I can tell you is that there are several blood tests that can be performed to ascertain if someone has contracted hepatitis C virus (HCV). Different physicians use different tests or combinations of tests, depending on the situation. Personally, I order an anti-HCV antibody test (antibody to HCV) using either EIA (enzyme immunoassay) or CIA (enhanced chemiluminescence immunoassay) and /or a qualitative HCV-RNA PCR depending on the individual situation and patient circumstances. There are both qualitative and quantitative tests available for HCV, which utilize HCV-RNA PCR technology. The qualitative tests detect whether HIV is present in the blood and has become the "gold standard" for diagnosing HCV in many settings. The quantitative tests detect the amount of virus in the blood and are primarily used to monitor efficacy of anti-HCV therapy. The HCV QuantaSure Plus assay is a quantitative HCV RNA-PCR test that uses the Roche TaqMan technology for simultaneous amplification and detection of HCV RNA. This allows the test to have a greatly improved dynamic range over the more standard PCR assays. It measures HCV values from 10 IU/mL to 100,000,000 IU/mL. When using PCR technology, a single positive PCR test is conclusive and confirms that HCV infection is present. However, a single negative test does not absolutely prove that a person is not infected. In other words, in rare cases HCV may be present in the blood, but not found by a single PCR test. When HCV is suspected and the PCR is negative, the PCR should be repeated. As you can see, this gets a bit confusing. Your doctor should be able to review your HCV risk and laboratory studies to ascertain if any additional or repeat studies are warranted. I have no information about your potential risk for HCV; consequently, it's difficult for me to give you very specific advice.

I'll reprint some information from the CDC that addresses frequently asked questions about HCV testing. Don't get frustrated if this seems a bit nebulous. It's difficult to explain over the Internet exactly how and why we order various diagnostic tests to evaluate HCV risk depending on the individual patient and individual circumstances. Your physician should have no difficulty in definitively screening you for any type of hepatitis and/or STD. OK?

Dr. Bob

What blood tests are available to check for hepatitis C?

There are several blood tests that can be done to determine if you have been infected with HCV. Your doctor may order just one or a combination of these tests. The following are the types of tests your doctor may order and the purpose for each:

A) Anti-HCV (antibody to HCV)

EIA (enzyme immunoassay) or CIA (enhanced chemiluminescence immunoassay)

Test is usually done first. If positive, it should be confirmed. RIBA (recombinant immunoblot assay)

A supplemental test used to confirm a positive EIA test. Anti-HCV does not tell whether the infection is new (acute), chronic (long-term) or is no longer present.

B) Qualitative tests to detect presence or absence of virus (HCV RNA)

C) Quantitative tests to detect amount (titer) of virus (HCV RNA) A single positive PCR test indicates infection with HCV. A single negative test does not prove that a person is not infected. Virus may be present in the blood and just not found by PCR. Also, a person infected in the past who has recovered may have a negative test. When hepatitis C is suspected and PCR is negative, PCR should be repeated.

Can you have a "false positive" anti-HCV test result?

Yes. A false positive test means the test looks as if it is positive, but it is really negative. This happens more often in persons who have a low risk for the disease for which they are being tested. For example, false positive anti-HCV tests happen more often in persons such as blood donors who are at low risk for hepatitis C. Therefore, it is important to confirm a positive anti-HCV test with a supplemental test as most false positive anti-HCV tests are reported as negative on supplemental testing. Click here for more information on Guidelines for Laboratory Testing and Result Reporting of Antibody to Hepatitis C Virus.

Can you have a "false negative" anti-HCV test result?

Yes. Persons with early infection may not as yet have developed antibody levels high enough that the test can measure. In addition, some persons may lack the (immune) response necessary for the test to work well. In these persons, research-based tests such as PCR may be considered.

How long after exposure to HCV does it take to test positive for anti-HCV?

Anti-HCV can be found in 7 out of 10 persons when symptoms begin and in about 9 out of 10 persons within 3 months after symptoms begin. However, it is important to note that many persons who have hepatitis C have no symptoms.

How long after exposure to HCV does it take to test positive with PCR?

It is possible to find HCV within 1 to 2 weeks after being infected with the virus.



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