Urine Test Confirm Cutoff/Error Question

[tzr916]

Knew a test was coming so abstained for 10 days & drank water like crazy. Picked up two home tests from local drug store & both home tests said I passed (negative result). Submitted to official medical test and came up positive by 4ng/mL:

Screening Cutoff = 50 ng/mL
Confirm Cutoff = 15 ng/mL
Confirm Quantity = 54 ng/mL

If the confirm cutoff is 15ng, shouldn't a positive need to be at least 65ng (50+15)? Isn't the 15ng the error threshold? If not, what is "confirm cutoff" ?

tzr916 Reviewed by tzr916 on 09-30-2009. Urine Test Confirm Cutoff/Error Question Knew a test was coming so abstained for 10 days & drank water like crazy. Picked up two home tests from local drug store & both home tests said I passed (negative result). Submitted to official medical test and came up positive by 4ng/mL: Screening Cutoff = 50 ng/mL Confirm Cutoff = 15 ng/mL Confirm Quantity = 54 ng/mL If the confirm cutoff is 15ng, shouldn't a positive need to be at least 65ng (50+15)? Isn't the 15ng the error threshold? If not, what is "confirm cutoff" ? Rating: 5

[killerweed420]

GC/Ms is the confirm quantity set at 15ng.
You were at 54ng.
You're fucked.lol

[tzr916]

Please

More explanation of what "Confirm Cutoff = 15 ng/mL" means... And less comedy at the expense of my life crushing job loss, probable mortgage foreclosure, and increased chances of suicide in the near future...

[slantedeyes]

should have thought about that before you smoked. Its a shame you were so close to passing. Missing by 4ng really sucks.

[slantedeyes]

Confirm cut off of 15ng mean that after they did the original cutoff it was more than 50ng. If the inital cutoff would have been 49ng or less they would have not sent the sample for gs/mc cutoff of 15ng. The second confirmation showed you were 54ng. That is why i said you were so close to passing the first step of 50 ng. Basically like killerweed stated you are fucked.

[tzr916]

Confirm cut off of 15ng mean that after they did the original cutoff it was more than 50ng. If the inital cutoff would have been 49ng or less they would have not sent the sample for gs/mc cutoff of 15ng. The second confirmation showed you were 54ng. That is why i said you were so close to passing the first step of 50 ng. Basically like killerweed stated you are fucked.

I completely understand that 54ng is over 50ng, but I still don't get what 15ng is???

[slantedeyes]

The 15ng means that the second confirmation must come in at 15ng or less for the test to be negative. You came in at 54ng. Now you see how close your were to passing the first confirmation that it would have never gone to the second confirmation if your first confirmation was 49ng or less.

[tzr916]

The 15ng means that the second confirmation must come in at 15ng or less for the test to be negative. You came in at 54ng. Now you see how close your were to passing the first confirmation that it would have never gone to the second confirmation if your first confirmation was 49ng or less.

Ok.
So they don't reveal what the second confirmation actual quantity/result is?
Is 50ng quantity on the first somehow equal to a 15ng quantity on the second, or something?
15ng is very confusing...

[kermitthehermit]

If your first sample tests above 50ng, the lab confirms the positive test with another, more sensitive test. If that test comes back below 15ng, the presumption is the first positve result was erroneous.

And I'm with you, no need for lectures. And intrusive tests that change your life are not funny. People come here for support and advice. Let's try to keep that in mind.

[Burnt Toast]

Even though the cutoff numbers are different, a 50 ng assay screen is essentially equivalent to the 15 ng GC/MS. The difference is the assay screen recoginzes the composite of the 31 metabolite concentrations. THC enters the body in its ingested form and exits the body as 31 metabolite concentrations, the most prevelant form being the THC-COOH metabolite concentration.
In order to test negative, the whole composite must test below 50 ng.

The GC/MS has a lower cutoff at 15 ng because the machine only recognizes 1 metabolite concentration (THC-COOH). In order to test negative, that one metabolite concentration must test below 15 ng.