The Role of Confirmation Testing

Urine drug screening is an effective tool to rule out the presence of drugs in the donor’s sample.  Drug screening technology provides a reliable, rapid and inexpensive means of ruling out drug abuse.

The most common drug screens are immunoassays.  Immunoassays employ a concept that is similar to a vaccination.  The test drug is an “antigen”, in this scenario it is similar to a virus.  The test reagent includes an “antibody”, this is similar to the antibodies produced by our body when injected with an antiviral vaccine.  If drug is present in the sample, it reacts with the antibody.  This reaction is measured and reported as a positive drug screen.

The reliability of a urine drug screen is at least 97%.   One factor that may cause a “false” positive result includes “look alike” drugs.  The amphetamines are the class of compounds that are most at risk for this issue.

The immunoassay used by Ammon Analytical Laboratory detects amphetamine, methamphetamine and MDMA (“Ecstasy”).  High amounts of chemically similar compounds may cross-react and cause a positive Amphetamines assay. Amphetamine-like drugs include ephedrine, pseudoephedrine, and phenylpropanolamine (PPA).  Confirmation testing rules out “false” positives.

The role of confirmation testing is to provide an alternate scientific method that positively identifies the drug(s).  The most common confirmation method is GC-MS (gas chromatography-mass spectrometry).  GC-MS provides a positive identification of the drug; it gives information about the drug’s chemical structure.  The reliability of GC-MS is at least 99%. GC-MS identification is analogous to a “fingerprint” of the drug’s chemical structure.

Some drug screens detect a class of compounds, such as, opiates, benzodiazepines, and barbiturates. There are as many as six or more compounds in each of the noted drug classes.  Many donors provide a prescription when confronted by a positive drug screen result.

 “The positive Benzodiazepines screen was due to the Klonopin I take.”

When GC-MS was performed, it was learned that the result was actually due to Xanax.  The strength of GC-MS includes the ability to identify the different substances that make up a drug class.  Similar scenarios can be imagined for the other classes of compounds.

When the consequences of a positive drug screen are severe, such as incarceration or child welfare issues,  confirmation testing must be considered.  The positive result must be as reliable as possible, i.e. beyond a shadow of a doubt.

If you have any further questions or need to discuss how to request a confirmation test, please contact one of Ammon Analytical’s professional staff at 866-857-8378.

Post Written by: Jerry Meenan

Reliability of Point of Collection (POC) Testing

iCup Drug Test Kit

     Point of Collection (POC) testing devices are a rapid and reliable means of testing for drugs of abuse in a variety of circumstances.  POC devices, such as the iCup, provide quick screening results that identify presumptive positive results.

Presumptive positive results should be confirmed by an alternative scientific method, e.g. gas chromatography/mass spectrometry (GC/MS).  In our laboratory we offer GC/MS confirmation of presumptive positive urine results.  Confirmations are done on urine samples tested by POC devices and laboratory based testing.  The results are essentially the same – the majority of specimens confirm positive.  Opiates, cocaine, and marijuana, all confirm and show good agreement between the iCup POC devices and GC/MS.  Amphetamines do not always confirm positive because of the many sympathomimetic-like compounds in the marketplace.  The issue of cross reactivity is a problem whether the screening test is a POC device or laboratory based.

Ammon Analytical Laboratory’s extensive experience with the iCup POC device and GC/MS confirmation demonstrates that the reliability is the same as laboratory based testing.

Post Written by: Jerry Meenan

Diabetic Patients Test Positive for Ethanol

Synthesis of Ethanol by bacteria in urine may cause false identification of alcohol consumption. Scientific studies have demonstrated ethanol production from either bacteria added to urine containing glucose or urine containing yeast and glucose.

The risk of glucose in the urine of a diabetic patient is high.  Microbial fermentation of the glucose to produce ethanol is likely.  Bacterial contamination of the urine because of a urinary tract infection can occur.  Thus, the likelihood of a positive Ethanol result in the urine of an uncontrolled diabetic patient is possible.

More more information or questions concerning alcohol testing, contact Ammon Analytical Laboratory.


Cross-reactivity Information for Immunoassay Screening Tests

Immunoassay screening tests provide rapid and reliable results for Urine Drug Tests.  On occasion a positive result is questioned by a client.  Is the positive test a “False Positive” result, i.e. caused by a substance other than the intended drug for the assay.  On the other hand, the patient may be taking a drug that is not readily identified as a member of a Drug Class.  The following table summarizes the immunoassays that are performed at Ammon Analytical laboratory and their respective cross-reactivity information.

Cross-reactivity information PDF:    Cross Reactivity


Post Written by: Jerry Meenan

Ethyl Glucuronide (EtG) New Developments and Concerns

Ethyl glucuronide, EtG,  is a biomarker for recent alcohol use.  The media has reported that individuals have been accused of abusing alcohol because of a positive EtG test result.  Only to find out later that the individual was accidentally exposed to alcohol in a cleaning agent or hand cream.  Similar to other drug test results, such as opiates and cannabinoids,  if the cutoff is too low, a positive due to accidental exposure is difficult to rule out.

A number of years ago the cannabinoids test cutoff was 20 ng/mL to identify marijuana abuse.  A number of instances were reported in the scientific literature of positives due to passive inhalation.  The drug testing community responded by raising the cutoff levels to 50 ng/mL in order  to rule out wrongly accusing an individual of marijuana abuse.  Similarly,  the opiate test cutoff was 300 ng/mL to identify opiates abuse.  When it was identified that poppy seed containing foods might cause a positive opiates drug test,  agencies such as the Department of Defense reacted by raising the cutoff to 2,000 ng/mL.  Thus, individuals would not be wrongly accused of opiates abuse.

EtG is a biomarker of alcohol ingestion, but definitive data about a reliable cutoff  to differentiate between alcohol abuse and accidental exposure is still under investigation.

Information in the scientific literature has reported that levels greater than 500 ng/mL are extremely unlikely to be caused by accidental exposure to alcohol.  Hearsay information describes an individual who only used a hand sanitizer and tested positive for urinary EtG  at a level of about 750 ng/mL.

Because of the concerns about accidental exposure to alcohol containing products,   Ammon Analytical Laboratory has adopted a prudent approach to testing for urinary EtG.

The screening cutoff for EtG is 500 ng/mL.  All positive EtG results are confirmed by an alternate scientific method, mass spectrometry.  Thus,  Ammon Analytical Laboratory provides a reliable means of identifying urinary  EtG.

Similar to other laboratory tests a positive EtG result should be used as a sign.  In this case a sign of alcoholic beverage consumption.  Upon reporting the result to a physician further evaluation of the donor is important.

Post Written by: Jerry Meenan