Drugs of Abuse Testing

• This test is intended to be used by a physician or trained drug abuse counselor and interpreted in the context of the patient's symptoms and clinical and medication history.
• This is a screening immunoassay to identify drugs of abuse by class.
  Note: This test is performed on urine specimens only.
• This test has a high negative predictive value.
• Cross-reactivity: this test has a false-positive rate of approximately 5%.
  Note: The false-positive rate varies by analyte.
• Positive results are not definitive, and should be considered presumptive.
• This test is not intended to be used for employee drug screening.

The advantage of this test is low cost. The cross-reactivity of the antibody used in the assay varies by drug. For example, the test for amphetamines detects amphetamine with greatest sensitivity, but it cross-reacts with over-the-counter (OTC) sympathomimetics, such as pseudophedrine, if they are present in urine at high concentrations.

• This test is designed for clinical circumstances where the patient may be inclined to deny the test results.
• The test uses the same immunoassay as the Drug Abuse Survey to screen samples but also includes confirmation of screening results by more definitive analytical techniques.
  Note: This test is designed to provide definitive test results.
• All positive screen results are confirmed by gas chromatography with flame ionization detection (GC-FID), gas chromatography/mass spectrometry (GC/MS), or liquid chromatography/tandem mass spectrometry (LC/MS/MS).
• This test can be ordered in a variety of configurations, differing only by the target drugs.

When results must be definitive, the Confirmed Drug Abuse Survey provides a fast and cost-effective approach to screening for drugs of abuse. It takes advantage of the negative predictive value of the immunoassay screen and couples it with the true-positive capability of the confirmation techniques. When a drug is present, the report identifies the specific drug and concentration.

• These tests are designed to evaluate a patient known to use a specific drug.
• Tests are available for each drug of abuse class.
• This test is designed to detect lower concentrations of a drug.
• This test is useful when a drug may have a low cross-reactivity in the screening assay (eg, oxycodone in the urine opiate assay).
  Note: More sensitive and specific than screening tests.
• All drugs tested are named in the report.
• Concentration is reported down to the limit of quantitation (LOQ) of the assay.

Available confirmation tests include:

Urine

Amphetamine Confirmation, Urine

Barbiturate Confirmation, Urine

Benzodiazepine Confirmation, Urine

Cocaine Confirmation, Urine

Fentanyl Confirmation, Urine

Ketamine Confirmation, Urine

Lysergic Acid Diethylamide (LSD) Confirmation, Urine

Opiates:
     Opiates Confirmation, Urine

Methadone Confirmation, Urine

Methaqualone, Urine

Phencyclidine (PCP) Confirmation, Urine

Propoxyphene, Confirmation, Urine

Tetrahydrocannabinol (THC) Confirmation, Urine

Serum

Fentanyl, Serum

Ketamine, Serum

Opiates:
     Morphine, Unconjugated, Serum
     Oxycodone, Unconjugated, Serum

Methadone, Serum

Propoxyphene, Serum

• Tests to monitor serum levels of drugs to determine if a patient is receiving the optimum dose are also available from Mayo Medical Laboratories.

View more information on therapeutic drug monitoring.

Mayo Medical Laboratories does not perform workplace drug testing. In other circumstances where the test results could be challenged in a court of law, a chain of custody process should be utilized.

• Chain of custody starts at the time of initial patient contact. The specimen must be collected under controlled conditions. The collection facility initiates a documentation process that accompanies the specimen to the laboratory. The chain-of-custody process provides:
  • Clear and unique identification of the subject being tested
  • Clear and unique labeling of the specimen
  • Identification of all persons who handle the specimen—legible signature required
  • A historical record of events with action dates clearly stated
  • Security of the specimen using a sealed, tamper-evident process

Failure to complete the collection process correctly, including labeling of the sample, as well as all details of the accompanying documentation, may result in the inability to process the sample.

A convenient kit is available to facilitate the chain-of-custody process.

• This test is intended to manage an apparent overdose, intoxicated patient, or determine if a specific set of symptoms might be due to the presence of drugs.
• This test is designed to detect those drugs that have toxic effects, but drugs for which there are known antidotes or active therapies to treat the toxic effect.
• This test is not appropriate for detecting drugs of abuse. The test is not designed to screen for intermittent or illicit use of drugs.

The prescription and OTC drug screens are available to test for a broad spectrum of drugs in serum and urine. Testing is performed by GC/MS. When drugs are identified above the reportable (detection) limits in the specimen, they will be reported as "Present."

Note: Alcohol, LSD, digoxin, lithium, tetrahydrocannabinol (THC), and some benzodiazepines, opiates, amphetamine-type stimulants, and most drugs of abuse are not detected by this procedure. For these drugs, the specific confirmation tests should be ordered.