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What do these drug test numbers mean?
Report is from Quest Diagnostics.
Test name: Marijuana by GC/MS, Urine
In Range column: 57
Out of range column: blank
Reference Range: ng/mL
Detection Limit: 15ng/mL
What does the 57 represent?
What specifically is this test measuring for – all marijuana related metabolites or THC COOH?
Was this a print-out provided at the collection facility, or results of the test sent later? In the case of the former the "57" refers to integrity of the sample, i.e. not-diluted, and could only be creatinine. If it is final results there are a lot of numbers missing.
If GC/MS, unusual unless as confirmatory test following an immunoassay (IA) positive, the metabolite would normally be THC-COOH (in urine). It is possible however to quantify THC, 11-OH THC, and THCCOOH proportionally for forensic purposes but usually only in blood.
Much depends on the purpose of the test, who ordered it and how much they are willing to spend. Quest offers many custom tests as well as the standard 5 panel > GC/MS.
To give you an example of why it's not possible to interpret numbers or procedures in isolation: SAMHSA regulated tests for federal employees restrict the means, methods and procedures of a test including what can be tested for in the confirmatory level. Non-regulated tests (employment, court etc) have no such restrictions and are developed around client needs and purposes---Could be testing for anything with or without cut-off.
The 15 ng cutoff is standard in THC confirmation (GC/MS) but usually only following a positive at 50 ng by IA.
This test was ordered by my personal physician at my request to confirm a positive immunoassay test.
I had anticipated receiving a report indication whether the THC COOH was either above or below 15ng. The way it was explained to me by the doctor's office is this number 56, read in conjunction with detection limit, meant I had 41 ng of "marijuana" in my urine. They were not able to tell me what specific marijuana related substances were included in that measurement. I think they may have tested for all metabolites instead of THC COOH, which is what I believe the positive immunoassay will be tested for. Quest termed the test "complete and confirmed." I think it was Quest test number 4846.
Does that additional info help?
The GC/MS is an extremely precise instrument. It isolates and quantifies each metabolite... the IA that you took does not... therefore the value of the GC/MS. It should not be reported as above or below the 15ng threshold (+ or -) but rather precisely quantified. There is no need or excuse for adding, subtracting or guessing about results. As you explain it I believe your physician 1) misunderstands the test, and 2) has, or should have, the complete printout.Quote:
Originally Posted by lacrosse1
The 15ng/ml is a cutoff below which the test is negative and not quantified. That is the only purpose of that number. If THC is present above that level then the quantitative result should be reported. That is true for any compound tested for. As example if your result was in fact 41 (I'm sure it wasn/t) the form should report that THC-COOH = 41ng/ml. The cutoff is advisory, identifying limitation and is not subtracted from any other number.
4846 is a Quest Test for Marijuana metabolites by GC/MS.
I am even more confused by the number 57. I can see how you would be confused by the incomplete results. The very purpose of this test is precision, and believe me it is precise. You and/or your physician are simply not being provided with the information that you paid for. Your physician is probably accustomed to lab results provided for urine and blood tests and obviously unfamiliar drug testing interpretation, a different animal.
You should, or ask the doctor to, contact Quest and obtain a complete report. Quest does millions of these tests each year and is usually very thorough in their processes. In your case, somewhere in the chain of responsibility, something or someone got off track.
Please let me know what the 57 was. GC/MS results are not reported in ranges.
ADDED: The IA would not isolate THC metabolites, therefore could not tell you which existed. It is not unusual for other cannabinoid metabolites to cross react with COOH screens.
Thanks for the response. It was very helpful. I am waiting to talk with the doctor. I believe you are right about the drug test being a different animal. I like my doctor a lot, but he is a GP and I don't think he has much experience with drug testing.
Do you have any suggestions on what he should request from the lab?
A complete printout of the results. It will contain the exact amount of each analyte/metabolite they tested for (probably only COOH). The GC/MS as noted measures ng/ml (that's parts per billion). So you should have an exact measure. In the event the test included other metabolites CBN, 11OH, etc, let me know, but I doubt it (in urine).Quote:
Originally Posted by lacrosse1
A lack of understanding of drug tests isn't a flaw peculiar to your doctor. According to an NIH funded study "Family medicine physicians who order urine drug testing to monitor their patients on chronic opioid therapy are not proficient in their interpretation." Even among certified pain management physicians, few doctors understand how to interpret the tests they order, according to the Annals of Clinical and Laboratory Science. Studies indicate that only 12% of physicians who regularly order drug tests understand the tests and know how to interpret them.
First I wanted to say I forgot to mention that in response to a question asked Quest told my doctor last week that my THC COOH was in the range of 4-16 ng/ml. They would not say how they determined that.
The doctor called back regarding the results. He said I tested positive for marijuana. I asked what the 56 was and he said marijuana. He did not ask if that was THC COOH despite my written request. However, he said he thinks the 56 may be the THC COOH level. The doctor kept focusing on the presence of marijuana in my blood and that I have a problem.
He was not very helpful. However, he did agree to call Quest back tomorrow and clarify what the 56 is a measurement of. I asked if he could get a printout of the lab analysis and he said there was not one available.:(
That is simply not the way drug testing is done. If Quest performed a GC/MS analysis on your urine sample they have a printout. The results are not something they write on the back of their hand and later call the doctor with. You paid for a very expensive analysis and have the right to see every component of it.Quote:
Originally Posted by lacrosse1
There is no such thing as marijuana in this test. They can only detect specific metabolites of ingested/metabolized cannabis, THC, THC-COOH, THC-OH, etc, one or a combination. The report should specify one or more of these and the quantity of each. It will also list the instrumentality used in the test and should list creatinine, specific gravity of the sample.
Oral representations don't cut it in drug testing. The results can have life-altering repercussions. Demand a full report directly from Quest. It makes no difference what your doctor "thinks" the number might represent or what someone on the other end of the phone "says" the number represents or some supplemental figures transmitted via telephone. It is out of context, ambiguous and requires precise clarification. If necessary, there are a number of agencies that can be contacted to force release of your results.
There is something awry with this entire process as you have explained it and that is exactly why a written report must be obtained. You could go on forever with this "they said-maybe this or that" routine. Quest is entirely familiar with the exactitude required of the testing process and the chain of responsibility that attaches.
I have no idea where the problem resides but, once again, this is not the way drug testing is performed, interpreted or reported.
The doctor called back today. I wasn't home and he spoke with my wife and told her he could not get anymore information from the lab. I guess I learned a lot about my doctor through this process.
Quest Lab reported TCH out of range as 247. How long do I need to be clean to test negative?
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