TOPIC: QUANTITATIVE PCRs with LLOQ missing - UK

HI All,

I just had a QUANTITATIVE PCR done through a private medical testing service here in UK.
Many of these services, indeed many UK private consultants use this lab:
"The Doctors Lab", Wimpole St, London.

My QUANTITATIVE PCR came back UND, but with no quantitative limits on the report.
(LLOQ - lower limit of quantification)
On my first enquiry I was told that the reason for no LLOQ was that I was UND. To anybody with half a brain, that is obvious rubbish.
The test limits are the test limits, irrespective of the result.
I have made further inquiries but with no further comment forthcoming.

Now I think that this is no small thing for anybody in the position of dealing with small numbers of detected virus. You want to know if your result is UND under the LLOQ. What if the LLOQ were something like 600? You'd go away thinking that you were UND when you might still be in the 599 region of detected virus. THAT'S NOT GOOD ENOUGH.

So I'm posting this to all, so that you don't spend your money and get a report back which for your purposes might be useless.
Why don't The Doctor's Lab put the LLOQ on their reports?
Until I find the answer to this question I'll not be using them next time.
If there is anybody out there that can add further info. I'd appreciate it.
For example, did your results from The Doctor's Lab come back not UND and with an LLOQ published?

dt

How very frustrating

Yes, LG. But I'm not done with this subject yet. I still have to get more PCR's, so either I can get this resolved with The Doctor's Lab or I have to find another UK lab to do them.

For heaven's sake - all I want to know is to what sensitivity the test works. It's not rocket science. I need the LLOQ to put the results in context. I mean, I could take a tube of my blood and look at it and pronounce that I am UND because I don't see any virus in it. The issue is - if the virus is indeed there, how much needs to be there for me to see it?

If a patient is only monitoring for a relapse after EOT then it is not that important because when there is a relapse the numbers go up very quickly, so any PCR will detect them. So in my case I might still use The Doctor's Lab. However for somebody like you who's numbers are going down slowly, you absolutely need to know at what numbers the vl count goes from quantifiable -> detected but not quantifiable -> not detected. I could live with an LLOQ at not more that 15, preferably less, but I would still need to know what it is.

Watch this space ......
dt

Don't know if this makes any sense but maybe below their "high" LLOQ, they would still see a virus but not know how much. And maybe at UND they can't see any virus at all. Maybe?

Yes, that's what I meant by frustrating - I wonder who you had on the phone? Maybe it was someone a bit clueless? Can you call and ask to speak to someone else maybe? or even better, email ?
Really, here in England, nothing ever seems to work properly, drives me nuts.

As you know , I looked up private VL tests, £245 - Then found a cheaper one, (a hundred and something) but the wait for result was 11 working days ... There is just this frustrating feeling with everything, chasing them up, things unanswered etc - As you know I had an issue with Blue Horizon too last time I used them.

It would indeed be extremely helpful if we could find a reliable service and post it on here for all, that's for sure. Seems so difficult!

Ken - Many thanks for chiming in here.

Anyway, here's what I expect to get from a VL report -

a)
DETected and the VL number given.
b)
DETected but no number because there were some virus found but not enough to count.
d)
UNDetected

However, to properly put these results in context I need to know the SENSITIVITY of the test. ie,
DOES UND mean that the test can't see any virus below 10? Below 15? Below 500?

We know that there can be virus still there, even if the most sensitive PCR can't see it. We all live with this concept. However, some people are monitoring small declines in their VL. To them it makes all the difference in the world if the test stops being able to see any virus at 500, or if it can still see the virus all the way down to 10. It's like trying to encapsule the meds with a scale that only measures to grams when you need it to measure to milligrams. Every scale tells you when you buy it to what limits it can measure accurately, right?

And every lab test also does. So why not put those limits on the PCR report? And why give me an answer which I can only call disinformation and double talk? Is their lab equipment not up to the same sensitivity as the competition and are they trying to keep that quiet?

Agree with you LG. We've both been through so much sub-standard medical service now that we shouldn't be surprised, but I still am. Indeed, has anything just worked first time, no problems. I think I'd be accurate to say - not much.

dt

Hi dointime,

When I have done viral load tests in private labs I checked the specifications of PCR method and LLOQ and price
on the lab web site.

I don't know this apply to you, but worth to check on the laboratory web site!

Yes I understand that. Just wondering the difference between seeing the virus and being able to quantify the virus. Hopefully if their machines can't quantify it below 500 or 50 or whatever, they can still see it, just not attach a number to it. It's all very frustrating. Maybe a doctor could chime in. That would be way cool....

hmm maybe they don't want to broadcast their detectable number because it's not very good?

Yes Ken, hopefully, but that 's not the difficulty.
If I know that the LLOQ is 10 then I know that even if it can't be quantified my vl must be between 0 - 10.
If I know that the LLOQ is 500, then I know that even if it can't be quantified my vl must be between 0 - 500.
The 2nd option is not good enough for some purposes. To continue with my metaphor, 0 - 500 is like having the gram scale.
0 - 10 is like having the milligram scale, which is what is required for some purposes.

And if I don't know the LLOQ at all, how do I know that somebody didn't just look at my tube of blood and say - nope, don't see any virus there, that one's UND.

dt

...but it's not their "detectable" number. It's their "quantifiable" number. Hoping there is a difference!

dointime wrote:
Is this your lab?

www.tdlpathology.com/about-tdl/publicati...hcv-multiplex-by-pcr

COBAS® AmpliScreen HCV Test, v2.0

Edit: Levels of Detection 15 HCV RNA IU/ml to 6.90E+07 IU/ml
LLOD=15

LG - there is a lab in UK - Quest Diagnostics.
www.questdiagnostics.com/uk/contact_us.html

I used them a while ago. Their parent company is big in the US. I didn't initially think of them because they have a strict policy to do tests only for doctors who are registered with them. That was a stumbling block for me but it might not be for you, dunno.

dt

Ken, you lost me there, don't understand, sorry.
dt

isaing4 -

What a star! Yes, that's the lab and it looks like you found the relevant info. I still need to digest it but -

Confirmatory Diagnostic Qualitative PCR
15 HCV RNA IU/ml to 6.90E+07 IU/ml

Which means that virus can be seen down to 15, although that's qualitative, not quantitative. That's good enough for my reading of UND. I know where I am with that. But what about LG? Can you see any info about the quantitative number? I mean, is it going to be able to distinguish between 150, 75, 25, .....

Thanks for this
dt