
Originally Posted by
Lauern12
I am curious about one thing concerning concentrations of creatine and etg. If the sample is in the range where it is not considered a dilute by the lab, but barely makes the cutoff for creatine levels and the etg levels just barely register under the cutoff, does that mean you pass? In other words if your creatine levels were on the high side and you gave a highly concentrated sample and the etg just registered over the cutoff, the lab would not adjust for the concentration and you would fail. Am I correct in my assumption that the labs do not take that into consideration for the most part?
Labs usually list creatinine level on the test results but do not adjust the EtG reading (called
normalizing). Anyone can make the calculation with both figures present but it is seldom done. Those administering or ordering the test usually have no knowledge of how to interpret results.
That is problematic as
all research recommendations since 2003 are based on this normalization. Recommended cutoff levels, ranges within which incidental exposure show up, are all based on creatinine normalization. Yet the labs and those using the test continue to rely on actual quantity in reporting and despite the recommendations of SAMHSA, the agency that regulates federal drug testing.
Most labs consider any creatinine reading >19 mg normal without further qualification.
Here is an example of an individual reported positive for EtG at 876 ng/mL. Creatinine was reported at 375. Test cutoff was 500 ng/mL.
Actual quantity measured: 876
Normalized to creatinine: 234
The formula is very simple:
100/creatinine X quantity of EtG: 100/375 X 876 = 234
This individual is a total abstainer. Hasn't had a drink in 30 years, either reading is clearly within range expected from incidental exposure, but the MD reviewing the test cut off her pain medication for non-compliance.
According to Greg Skipper, MD*
"Normal urine can vary up to 20 fold in concentration. The more concentrated urine will report 20 times higher EtG/EtS levels than more dilute."
*Dr. Skipper introduced this test in the US. His site provides valuable information.
The Role of Biomarkers in the Treatment of Alcohol Use Disorders, 2012 Revision Spring 2012, Volume 11, Issue 2, Department of Health and Human Services.