Why don't the labs make tests definitive before giving erroneous results?

[willy851]

I recently got tested for std's and hcv was one of them. I had a sexual encounter three months prior and wanted to get checked. The test came back and said patient is negative. Not infected with HCV unless recent infection is suspected. The level was .1 from 0 to .9 they didn't do any other test on it to prove it was HCV. The Doc said not to worry, but I am still a basket case. I thought it was hard to get HCV from sex.
I performed oral without protection but used a condom otherwise.

In reading I find that these tests come back false positive often.
I don't know if that is false positive or anything below a 1. is just negative.
My doctor doesn't seem to have a clue. I read articles on the CDC website that seem to suggest that this happens 35% of the time on people that are not likely to have been exposed.

Why would any Lab give results that could be misinterpreted by the patient, when most doctors are not experts in this area.
I have to get another test to make sure now, I can't wait six months like the doctor says.

[wyntre9]

"n reading I find that these tests come back false positive often."

Where did you read that?

My original bloodwork tested for HCV Antibodies.  When it came back positive, my doctor(s) ran more sensitive blood tests ( I don't know the names) to confirm the results.

The original test read HCV Ab 43.4 High, compared to the normal S/CO ratio of 0-.9 .

But there was a footnote that said samples with high s/co ratios (greater than 9.9) confirm positive (95%), but less than 5 out of 100 might represent false positive.

All the subsequent tests my doctor ordered confirmed the positive for HCV Ab diagnosis.

Unfortunately for me, I wasn't among the less than 5% with false readings.

Good luck.

[jmjm530]

False positive happen, but not a lot of the time. Sounds like you're OK, but based on "doctor hasn't a clue", I'd make an appointment with someone who does have a clue such as a  liver specialist (hepatologist)and let them put your mind at ease after reviewing your tests.

-- Jim

[copyman]

false "positives" although very rare are wrong only about 5%. but false "negatives" are even more rare and not sure but i would think not even 1% if that. relax and go on and enjoy your life. if you want get re-tested in 6 months but i do not think you have anything to worry about.

[willy851]

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.

[jboyhk]

Correct me if I am wrong but did not the dr tell you that you didn't have it and don't worry about it??

That means he had a clue.


You are reading too much into this test.

I won't pretend to understand everything about this test but it is NOT measuring the actual virus but what the body usually produces if it encounters the virus. The actual virus test is 10X more expensive and is usually done if the antibody test is positive.

What is your point? Do you want researchers to devote more time to come up with a 100% accurate antibody test instead of working in more helpful areas?

[jmjm530]

I think the CDC was using the phrase 'false positive' in the very broadest sense. What we usually term as false positives here are tests that come out positive but on re-test you get a negative. In your case, If you repeated your antibody test, you'd probably still get another positive, therefore the first positive was not "false". What it does mean is that your antibody test was positive. But a positive antibody test doesn't mean you necessarily have hep c.  It just means you're carrying the antibodies. To confirm HCV you need a viral load test, often called a PCR test. Hope this clarifies.

-- Jim

[jboyhk]

But he doesn't have an initial false positive. He tested negative.

My understanding of antibody tests is that some other virus', old flu's etc, may produce similiar antibodies like HepC. This is why there is a threshold limit of .9 to be positive.

I have a friend who 50%  tests positive on HIV antibody tests but always negative on HIV RNA PCR tests. That is because he has some conditions such as excema etc, and he someone naturally has similiar antibodies from HIV exposure. In HIV you have to test positive for maybe 5 out of 8 antibodies. I don't know exactly what it is for HCV but it may be 3 out of 4.

[jmjm530]

jboy: But he doesn't have an initial false positive. He tested negative.
------------------
LOL. Yes, it appears you're correct, thanks for the heads up. Didn't he post this before? I think I mentioned a false negative that time then but somehow missed it this time.

Anyway, so what he appears to be worrying about then is a "false negative" which as the report says would only be a factor if he had a recent infection and therefore the antibodies didn't have time to form yet.

His best bet is to have a viral load test and be done with the entire issue. I think we both suggested that in a follow-up thread.

Be well,

-- Jim

[bakou70]

Question: Being tested positive from chronic hepatitis B would mean that the person carrying the virus will die younger? I am 36 years old and got informed that I have chronic hepatitis B although I have never been sick except getting seasonally fllu symptom. I want to know if one could live longer (up to 80 years)having this desease? Or there is a limit in the life expectancy of the carrier? Do old people have Hepatitis B? Also is that mean that I can have children any more? Can one be infected by hepatitis B after being vaccined from it? I need answer to the foregoing set of questions. Thanks for doing that. I will be back in a couple or so hours.