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Lab Corp no longer offering <10 PCR.

Scared the c**p outa me for sure. As most of you know I dropped the RIBA a few weeks ago. Well I did a PCR, checking on break thru. When I called my lab lady she read the results saying "<43" HCV RNA not detected." I'm LIKE, what's this <43?? She doesn't know, she said it was the same test we've been doing from the start which is the 10 to 100,000,000 . (been UND <10 from week 2) Of course I'm thinking of the confusion during the Telaprivir trials and others. Well I'm a LITTLE worried at this point so she starts making calls trying to find something out. That was yesterday, got the word this morn. Lab Crop has stopped the 10-100,000,000 and in it's place is using a 43-69,000,000. The L.Corp lady told my lady that they considered this test more reliable and consistant. I am still UND. jerry
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Avatar universal
It is unfortunate that these test options are so confusing. In my experience, the docs and the NPs cannot keep up with all the options. Some patients choose Quest other LabCorp and others a third provider based on convenience. So if a medical office is going to keep up with these issues, they need to know the tests for multiple companies.

If you really care, the only way to get the best test is to inform yourself and then request a specific test from the doctor.

Apropos of HR's comments about IU vs. copies, I just received results from a LabCorp Quantasure test. The results were reported two ways: as copies with a cut-off of 5ml, and as IUs with a cut-of of 2ml. So at least in this case the 2.5 multiplier seems to be at play.

Note: if you want the super-sensitive LapCorp test you need to order Quantasure not Quantasure Plus. The first has a cut-off of 2 iu/ml the second 10 iu/ml. Are we confused yet?
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626749 tn?1256515702
Well, hate to tell you, but the NGI Superquant is <39..... test  # 140612

The test you wanted is NGI HCV QUANTASURE <2 is.... test # 140639

https://www.labcorp.com/pdf/One_Source_Infectious_Disease_Reference_Guide_1394.pdf


apache
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338734 tn?1377160168
I just had the NGI Superquant test drawn at Labcorp. I had to research the test code to get the right one as docs office could not find it. This test supposedly has a detection limit of <2 IU/ml. The previous two PCR tests I had done from Labcorp resulted in a substitution of a test with a limit of about <40 IU/ml.  I thought I was getting the <10 IU test and was shocked just like Orleans.

I'll see for sure in a few days when I get the results.

Brent
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Avatar universal
HR : the following published eurohep I/II summary
http://www.ncbi.nlm.nih.gov/pubmed/8783163
doesn't seem to rank the methods submitted. Is a more detailed summary available?

CS,Apache: the following, free-access, refs  may be helpful if interested in the details of quantification.

http://www.ncbi.nlm.nih.gov/pubmed/7665645
http://www.ncbi.nlm.nih.gov/pubmed/8385151
http://www.ncbi.nlm.nih.gov/pubmed/1452654

all, a bit dated now, cover introduction of  Roche's rna quant (amplicor ). I've never seen market share stats, but from the number of papers that reference that test, it seems one of the most common. The first two discuss the innovation of combining the polymerase needed for pcr with the reverse transcriptase, the third, which has nothing to do with hcv, discusses the use colorimetric detection of the the pcr product, the step that yields the copy number. From the methods section, my understanding of the basic recipe is: extract rna from serum, transcribe to dna, synthesize a dummy template with same end sequence that can be added at known concentrations, run pcr, run gel and Southern blot to purify product, hybridize product to probes in microwells, scan plates to get OD reading and convert this to copy number.

After all that, getting a count within an order of magnitude of the actual number of rna molecules seems nothing short of a miracle (and I'm not sure competing methods are any simpler).

From a patient's perspective, the take home messages seems to be (1) for purposes of low-level vl comparison pick one test and stick with it,  (2) consider any vl measurement as a range of +-  ,5 log units.
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626749 tn?1256515702
HR, thanks for responding to my question.

Its very interesting.

Do the NGI <2 test and the Heptimax use  
robust single copy detection.  
Or are those type of tests strictly used in research only.
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Avatar universal
MEDICAL PROFESSIONAL
600000 iu is the high Vl decision.
All labs should measure about the same iUs since they use the same internal standard.

Fluctuations in individual test accuracy are of course always present. This is called 1/reproducibility and inherent to the technology used .

The copy/iu differences reflect the fact that counting the virions, that means to determine the REAL COPY NUMBER in the standard itself requires extremely high sensitivity and technology and often comes out plainly off by quite a margin,. That's where the iu help, because the copies per iu factor is not as relevant as the capacity to compare in between labs, thus the same sample will have about the same iUs no matter where you send it. If you want to know the copy number, multiply the iUs by 2.5 and forget that some labs have a different ratio.
After all the iu standard DOES HAVE  A  CERTAIN INHERENT NUMBER OF COPIES. But how do you determine that number? It is extremely difficult, since you need what is called robust single copy detection so that you ( the laboratory)  can use the method of limiting dilution to measure the standard itself. The laboratory that achieved the highest level of sensitivity in two large international comparison tests for HCV sensitivity (Eurohep I and II) probably has the best way to actually count the copies/virions for the purpose of standardization.
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Avatar universal
MEDICAL PROFESSIONAL
The answer is in my post above:

The Labcorp code for the NGI Quantasure is LC 140639.

Once you are UND you might as well use the cheaper HCV NGI Ultraqual,
LC code 140609, it has the same sensitivity. thus if you are UND, you are very UND
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626749 tn?1256515702
==============================================================
quote from HR:
They key aspect is that this standard is used by all labs, so that the same patient gets approx the same value regardless by which assay he is measured.
=============================================================
HR, I  understand how the same patient gets approx the same value regardless by which assay he is measured by.
But doesn't the difference in actual iU/ml numbers between the tests have some clinical significance?

Amplicor HCV Monitor v2.0 ............. 1 IU/mL=0.9 copies/mL
Cobas Amplicor HCV Monitor v2.0 ... 1 IU/mL=2.7 copies/mL
Versant HCV RNA 3.0 Quantitative ... 1 IU/mL=5.2 copies/mL
Cx HCV RNA Quantitative ............... 1 IU/mL=3.8 copies/mL
SuperQuant ..................................... 1 IU/mL=3.4 copies/m


How about if a patients lab/Dr used a different baseline vl test, than the 12 wk test with its minimum 2 log drop cutoff point. Not uncommon for the baseline test to be a less sensitive test with reflex to genotype. Using different VL assay (just like orleans LabCorp did) could conceivably for some patients, make the difference to continue tx or stop as a non responder if going by IU/mL.

Low Vl 600,000, is it figured in iU/ml or copies/virions ?

So what would a Doctor do, use the actual iU/ml value on the test results, or research the copies factor number of the test used, and then translate to copies for his decisions on TX?  Is it common for Hepatologist to do this ?

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Avatar universal
I'm confused @ 12 weeks und used Lab corp 140639 ; now week 24 coming up what lab corp lab is necessary?
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Avatar universal
HR
From Standardization of Hepatitis C Virus RNA Quantification
Jean-Michel Pawlotsky,1,2 Magali Bouvier-Alias,1 Christophe Hezode,3 Francoise Darthuy,1 Jocelyne Remire,1 And Daniel Dhumeaux2,3

The situation has changed recently with the publication of 2 studies involving more than 1,700 treatment-naive patients with chronic hepatitis C and showing a significant benefit of combination therapy with IFN-a, 3 MU 3 times per week subcutaneously, and ribavirin, 1,000 to 1,200 mg/d orally, compared with the same dose of IFN-a alone.11,12 In these reports, both pretreatment viral load and the HCV genotype were independent predictors of sustained HCV RNA clearance after combination therapy.1

The cut-off point defining “high” and “low” pre-treatment viral loads was established as the HCV RNA load discriminating best between sustained virologic responders and nonresponders in the 2 studies.11,12
Both teams used the Superquant assay (National Genetics Institute, Los Angeles, CA),
an “inhouse” competitive PCR-based technique using multiple PCR cycles performed in a central laboratory.14 From these data the decision threshold was established at 2,000,000 copies/mL (i.e., 6.3 log10 copies/mL).11,12
More recently, the same authors reanalyzed their database and used the study group median viral load (i.e., 3,500,000 copies/mL or 6.5 log10 copies/mL) as the decision threshold.15

Unfortunately, these recommendations have been inapplicable on a global level, because most laboratories worldwide use commercial assays such as Amplicor HCV Monitor and Quantiplex HCV RNA.

Indeed, in the absence of standardized HCV RNA quantification units, 1 copy/mL in Monitor, 1 genome equivalent (Eq)/mL in Quantiplex, and 1 copy/mL in Superquant do not represent the same amount of HCV RNA in a clinical sample, these units having been defined independently, with quantified standards of different natures, lengths, and sequences. In addition, the same units can also vary from one version of a commercial assay to the next.16 Thus, 2,000,000 or 3,500,000 copies/mL in Superquant may not be 2,000,000 or 3,500,000 copies or Eq/mL in assays other than Superquant, meaning that these assays cannot be used to tailor the duration of combined treatment unless the exact correspondence between the various units has been established.


In other words HR its all your fault. -LOL
You know I am joking. It is ironic though.

So IUs came about because no one could work out how to convert from SuperQuant copies to whatever the other tests were using.

And this the bit I don’t understand
“do not represent the same amount of HCV RNA in a clinical sample,”

Why not. Either you detect a copy or you are detecting something that looks like a copy.
But 1 copy should be the same no matter what.
Or have I missed something

CS
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Avatar universal
MEDICAL PROFESSIONAL
Here is the root of the iU/copy difference;

The WHO standard, intended to be later used as a cross laboratory internal standard in 1999, used a genotype 1 sample that was "assigned' a value of 100000 "international units". That was an underestimate of the actual viral load, unfortunately, and the producers of this standard should have made an effort to determine the absolute Vl in copies or virions/ml , something that was regrettably not available to them. Thus this number in iu is always short/only a fraction  of the actual virion number. It would have been possible to determine the true copy number of this sample with good efforts and then assign one copy to be one international unit. They key aspect is that this standard is used by all labs, so that the same patient gets approx the same value regardless by which assay he is measured. That is very good and important. But they could have "assigned" the true number to this standard, not an estimate, that turned out to be too low.
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Avatar universal
MEDICAL PROFESSIONAL
Here is the abstract of the paper mentioned, I have the actual Journal in fron of me. I do however not see anything that fits the above remark by CS.

Standardization of hepatitis C virus RNA quantification.Pawlotsky JM, Bouvier-Alias M, Hezode C, Darthuy F, Remire J, Dhumeaux D.
Department of Bacteriology and Virology, Hôpital Henri Mondor, Université Paris XII, Créteil, France. jean-michel.***@****-hop-paris.fr

It was recently recommended that hepatitis C virus (HCV) RNA quantification be used to tailor the duration of combined interferon alfa (IFN-alpha)/ribavirin therapy in patients infected by HCV genotypes 1, 4, and 5. This recommendation has been difficult to implement in the absence of standardized quantitative units for HCV RNA. The aim of this work was to define clinically relevant HCV RNA loads in standardized international units (IU), for use in routine clinical and research applications based on standardized quantitative assays. Two hepatitis C virus RNA quantitative assays were used: (1) the Superquant assay (National Genetics Institute, Los Angeles, CA), for which possibly relevant thresholds were established; and (2) the semi-automated Cobas Amplicor HCV Monitor assay version 2.0 (Cobas v2.0, Roche Molecular Systems, Pleasanton, CA) that measures HCV RNA loads in IU/mL. Quantification in the Cobas v2.0 assay was linear over the entire range of values tested, including viral loads higher than 850,000 IU/mL after 100-fold dilution. The accuracy and precision of the measures in IU/mL were satisfactory with Cobas v2.0. The results obtained with Superquant and Cobas v2.0 correlated (r =.932; P <.0001). A value of 2,000,000 copies/mL (6.3 log(10) copies/mL) with Superquant was converted to nearly 800,000 IU/mL (5.9 log(10) IU/mL). In conclusion, all HCV RNA quantitative assays should give HCV RNA loads in international units and be validated with appropriate calibrated panels; 800,000 IU/mL in any of these assays should be used as the decision threshold to tailor the IFN-alpha/ribavirin treatment duration in patients infected by HCV genotypes 1, 4, and 5.

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Avatar universal
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Avatar universal
Sorry, that should have been "Jean-Michel Pawlotsky"
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Avatar universal
Have to run but here's the citation:

Hepatology, Volume 32 Issue 3 , Pages 453 - 680 (September 2000)

Standardization of Hepatitis C Virus RNA Quantification
Jean-Michel Pawlotski (and others)
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Avatar universal
Maybe the url is breaking up.  I condensed it here. Let me know if it works, if not I'll copy down the citations. Good to see you dropping in from time to time.

http://tinyurl.com/cb8vn7
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Avatar universal
MEDICAL PROFESSIONAL
Sorry link does not work. You have authors, title?
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Avatar universal
I think he may have been referring to the Superquant test mentioned frequently in this paper.

http://www3.interscience.wiley.com/cgi-bin/fulltext/106596948/PDFSTART?CRETRY=1&SRETRY=0
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Avatar universal
MEDICAL PROFESSIONAL
not sure was that actually means:

"the study that showed HVL or 2,000,000 copies was a neg used one of his tests.
and that couldn't converted easily to the other tests being used at the time. "

??

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Avatar universal
I am with you. It makes no sense.
While i can accept that the different amplication methods can produce different results
having a range of 0.9 to 5.2 for copies to IUs makes you wonder what it is thats actually being detected. It doesnt appear to be virons.

Indirectly IUs are all HRs fault anyway.
the study that showed HVL or 2,000,000 copies was a neg used one of his tests.
and that couldnt converted easily to the other tests being used at the time.

CS




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Avatar universal
The above comment is outdated on the current limit detection...but the ratio between I/U and copies /ml  seem to be about the same
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Avatar universal
Currently available PCR assays will detect HCV RNA in serum down to a lower limit of 50 to 100 copies per milliliter (mL), which is equivalent to 25 to 50 international units (IU).

http://digestive.niddk.nih.gov/ddiseases/pubs/chronichepc/
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Avatar universal
VIRIONS are virus particles: they are the INERT CARRIERS of the genome, and are ASSEMBLED inside cells,  from virus-specified components: they do not GROW, and do not form by DIVISION


http://www.mcb.uct.ac.za/tutorial/virions_are_virus_particles.htm
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Avatar universal
How is it standardized when one test uses 1ui/ml to equal 5.2 virons=iU/ml,  and another uses 1iU/ml to = 3.7 or 2.5, etc, as in your above chart of different tests protocols.
Isn't 1 virion equal to 1 virion standardization at its simplest ?
----------------------
I agree that 1 virion must equal 1 virion, but the chart and article showed different convesions between *copies* and IU/ml, not between virons and IU/ml as you're suggesting they might --  so I'm assuming that 1 copy does not necessarily equal 1 viron. If it does, then I need some clarification myself because then the whole IU/ml wouldn't make any sense and I don't believe even HR went that far, although I admit sometimes I don't follow completely some of his studied techincal explanations.

-- Jim
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