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How likely is a false positive HCV AB test?

I was recently tested and had a 1.0 on s/co ratio. My dr told me not to worry as I barely tested positive and it is more than likely not a true positive and assured me it is probably a false positive. I gave blood for the RNA test and am awaiting results to be sure. What are some examples of positive HCV AB results? Is 1.0 usually positive or what is the norm for positive individuals?
Best Answer
683231 tn?1467323017
Ok found some more information

“HCV INDEX: In order to improve the reliability of reported HCV Ab test results the manufacturer has established that all indexes > 1.0 are considered positive. However, the manufacturer's recommendation of the indexes reported can be interpreted in the light of the confirmatory strip immunoblot (RIBA) as follows:”

1.00 - 3.99 25%
4.00 - 7.99 77%
8.00 - 10.99 73%
> 11.00 99.9%

So basically while 1.0 is considered positive and additional testing is required to confirm infection with hepatitis c, for results between 1.0 and 3.99 the percent of people with that result who eventually do test positive is about 25%

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Avatar universal
False positives are quite common and there are many conditions that can cross-react. It used to be the ELISA was followed up with a confirmatory RIBA, which is basically a Western Blot. Then, they came out with a bunch of new drugs about 2013 and the RIBA went off the market. At the time, they said nucleic acid tests were "more reliable" - but they had been around essentially unchanged since 1997, which is really crazy because HCV wasn't even formally isolated and propagated in cell culture until 2005, so the EIAs you take today were never validated against the gold standard which is viral culture in vivo. They will claim stuff like 99% sensitive and 99% specific - but that's in a cell culture model - a bunch of laboratory hocus pocus.

A single EIA with a low signal to cutoff ratio even if coupled with detectable HCV-associated RNA should not be considered proof of infection, IMHO. Personally, I'd like to see these tests banned because they cause all sorts of anxiety and many people get overtreated with very toxic drugs - the whole HCV industry exists to sell drugs and test kits, not to help patients.

I'd step back and do a differential diagnosis and really evaluate the likelihood of risk exposures - if you're on a website like this are you really a junkie sharing needles? The evidence for HCV sexual transmission is surprisingly thin - the chance for most heterosexuals coming down with clinical hepatitis through sex is less than that of getting struck by a bolt of lightening. I'd also look at causes for cross-reacting antibodies. Any immune activation can cross react on an antibody test, and without the confirmatory test in the algorithm for a doctor to put you through this is cruel.
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683231 tn?1467323017
Did you get the HCV RNA by PCR results back yet?

Hoping you got good news
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683231 tn?1467323017
My question for you would be did you experience a risk of exposure?

Did you have a risk of having hepatitis c infected blood entering your blood stream?

“How Does Hepatitis C Spread?

Hepatitis C is spread only through exposure to an infected person's blood.

High-risk activities include:

Sharing drug use equipment. Anything involved with injecting street drugs, from syringes, to needles, to tourniquets, can have small amounts of blood on it that can transmit hepatitis C. Pipes and straws to smoke or snort drugs can have blood on them from cracked lips or nosebleeds. Get into a treatment program if you can. At the very least, don't share needles or equipment with anyone else.

Sharing tattoo or piercing tools. Nonsterile items and ink can spread contaminated blood.
Blood transfusions in countries that don’t screen blood for hepatitis C.
Nonsterile medical equipment. Tools that aren’t cleaned properly between use can spread the virus.
Blood or cutting rituals. Sharing the tools or exchanging blood can transmit hepatitis C.“

Medium-risk activities include:

Sharing or not disposing of grooming and hygiene supplies. This includes razors, toothbrushes, nail clippers, or anything else that could have your blood on it. Cover any open wounds or sores with bandages. Carefully dispose of tampons, sanitary napkins, tissues, used bandages, and anything else that might have your blood on it.
Unprotected sex. It’s rare, but you can spread and catch it from sex, especially during menstruation or certain sex practices like fisting. It’s more likely you’ll spread it if you have HIV or another sexually transmitted infection.
Pregnancy and birth. There’s a small risk for a mother to pass the disease on to their child before or during birth. The odds go up if the mother has HIV.
Needle-stick injuries. Health care workers and caregivers are most likely to get it this way.

Things that Don’t Spread Hepatitis C

It cannot be spread through:

Breastfeeding (unless nipples are cracked or bleeding)
Sharing utensils or glasses
Casual contact
Sharing food and water
Mosquito or other insect bites
That means everyday contact isn’t risky. The odds of it spreading between people in a household are near zero.
Helpful - 0
Never injected drugs and very low risk for HCV. Just wondering what normal positive results are for HCV AB test. I was told I was barely positive and that it is most likely a false positive .
A positive result is a positive result

Slightly positive is still a positive result.

The only way to know is to have the HCV RNA by PCR test that looks for the actual virus in your blood then you will know whether you are currently infected or not.

The most common reason for a so called false positive is when someone was infected in the past with hepatitis C but was able to resolve the infection on their own without medical intervention. About 25% of people initially infected with hepatitis c are able to beat the infection the remaining 75% will go on to be chronically infected and will need treatment to resolve their hepatitis c infection.

“What to know about false positives in hepatitis C testing”

Personally I have not seen anything in the literature to indicate a result of 1.0 on the antibody test is more likely to be a false positive. The testing parameters  say that a result of 1.0 is positive. I assume if what you say is the case they would revise the test result to require a higher score to indicate a positive result.

You should have the HCV RNA by PCR test results soon then you can move forward from there.

Just to add if you do test negative on the HCV RNA by PCR test you will likely always test positive for hepatitis c antibodies so if you do at some point suspect you may have been exposed to hepatitis c and are at risk of infection bear in mind you will likely test positive for hepatitis c antibodies and will need to have the HCV RNA BY PCR test to determine if you are infected.

Best of luck
683231 tn?1467323017
Diagnostic accuracy of tests to detect Hepatitis C antibody: a meta-analysis and review of the literature

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