4 replies to this topic

[Aussiegirl]

My Doctor uses  Genzyme Genetics lab for my BCR-ABL Quantitative RT-PCR analysis. The problem is that it takes 2 days to get to the lab. I believe I've read in Trey's blog that the sample degrades  by 50% within the first 24 hours. Am I wasting my time & money on this test? No BCR-ABL is found in these test yet after 4 years on Gleevec 400 mg my white count has never dropped below 14. How long should it take for the lab to run this test as it looks like it takes about 4 days before they send the report back to the pathologist.

[Trey]

Genzyme Genetics was bought out by LabCorp a couple years ago.  So LabCorp is your lab, I assume.

 

A PCR should ideally be run within 24 - 36 hours of blood draw.  Most labs will process the samples up to 72 hours after drawn.  However, a chemical can be added to extend the life of the sample and I do not know how useful that is.  Freezing works well, but most labs will not allow frozen samples.  If the stabilization chemical is being added to your sample (ask) then the timeline can be extended, but not all labs allow such chemicals to be added.

 

The report takes longer than the specimen processing, so you want to know how old the sample is when processed.  Ask your Onc how the shipping is done (should be express mailed within a couple hours of the draw).

 

Overall I cannot say if your samples are viable when processed.  Every sample is degraded to some degree, so zero degradation is not practical.  The lab tech visually looks for autolysis (breakdown of the sample) but that may not be good enough.  The only thing I can tell you is to call the lab which processes the sample and ask them what they consider to be acceptable timelines for PCR processing, what days they perform the test, and how they know the result is accurate.

 

Tips for assuring a viable sample:

1) Never have a blood draw on Friday.  Also avoid Thursday if possible.

2) Know when your lab processes PCRs.  Big labs are Monday - Friday, but many others are less often.  Then have the sample draw done to match shipping times.

3) Make sure your Onc knows you are interested in this issue, then he may become interested. 

Edited by Trey, 02 February 2015 - 03:37 PM.

[Aussiegirl]

Thank you Trey

[rcase13]

I asked my doctor about this because my blood for the PCR was drawn on a Friday. And being an astute forum reader I voiced my concerns about the viability of the blood. I was told not to worry because right after they draw the blood they "fix" the sample to prevent degradation.

 

I have no idea how they "fixed" the sample but I am happy! As long my results come back good I don't care what they do!

[Trey]

The same way they "fix" beef to make beef jerky.  Beef jerky tastes just like a fine steak but takes about 1000 years to degrade.

 

But actually, there are additives that slow down degradation but the PCR must be done differently.  Most labs won't fool around with that.  Ask your Onc what they put in it -- probably a wee dram from his flask.