Frequently Asked Questions

It depends. Many factors affect the test result including the patient, the specimen, as well as the laboratory test itself. Any result that is not consistent with expectation should be confirmed by another method, and investigated so you can be confident about the interpretation. The laboratory can be a partner to you in helping guide an appropriate investigation.

Most drugs are metabolized in the body, and it is the metabolites that appear most commonly in the urine. As such, the presence of parent drug in the absence of metabolites is unusual and could indicate that the drug was added directly to the urine. Specific questions about adulteration of a specimen with parent drug should be discussed with the testing laboratory. It is also possible that patients are unable to metabolize drugs due to genetic variation, impaired liver function, or drug-drug interactions.

Many drugs are eliminated and detected based on common patterns. For example, diazepam usually appears in the urine as a combination of nordiazepam, oxazepam, and temazepam. For buprenorphine, the norbuprenorphine glucuronide metabolite is most prominently observed. If the expected metabolite pattern is observed, it provides confidence that the drug was taken. It may also help determine the specific drug taken, as well as the approximate timing of the last drug administration. Specific questions about patterns of metabolites for a specific drug should be discussed with the testing laboratory.

In general, drug concentrations detected in urine and the dosage of a drug that was taken do correlate. However, the correlation is not precise, and urine concentrations cannot be used reliably to estimate what specific dose a patient was taking, or when the patient last took a dose, because of variation in amount of drug eliminated in the urine over time, and variation in the concentration of urine. Evaluation of timed blood concentrations, as per the fundamentals of therapeutic drug monitoring, is the preferred approach to estimating dose.

The opiate immunoassay (and the oxycodone immunoassay) in screen panels detect a rather narrow number of analytes, and normally do not cross react with other opioids such as buprenorphine, fentanyl, meperidine, tapentadol, or tramadol. The opiate immunoassay in the screening panels typically detects only codeine, hydrocodone, hydromorphone, morphine and the heroin metabolite (6-AM). Order quantitative LC-MS/MS test(s) specific for the opioid(s) that is not represented by the screen panel. See test menu

In urine, detecting a large amount of parent drug without (or with very little) drug metabolites usually indicates that the patient has added drug directly to his/her urine specimen (spiked, adulterated). This type of specimen adulteration may not be detected with a drug screen, but can be detected by ARUP’s quantitation tests that independently measure parent drug and common drug metabolite(s). Our buprenorphine paper shows some examples of the use of metabolite data in the detection of specimen adulteration. The lack of drug metabolites, however, does not always indicate adulteration: in rare cases, parent drug has been found without metabolite in urine of patients with compromised metabolism. In these cases the concentration of parent drug is relatively low compared to an adulterated sample.

The duration of time for which a drug can be detected is based on
(1) the pharmacokinetics of the drug itself,
(2) the dose and frequency of dosing,
(3) detection limits of the test utilized, and
(4) the quality of the specimen being tested.
Most drugs are detected in urine for 24-48 hours after last use. Some drugs are detected for shorter durations (e.g. methylphenidate, some benzodiazepines) and others for much longer (e.g. methadone, marijuana). Contact the laboratory for estimates on detection periods for a specific drug, or consult the half life and detection chart.

False positive rates in urine immunoassays are generally <5%, with the exception of amphetamines, which are notorious for false positives.

No. Methylphenidates do not belong to the class of amphetamines, and immunoassays for amphetamines do not detect them. Furthermore, the half-life of methylphenidates is very short (~ 2 hours). To monitor compliance for methylphenidates, a quantitative LC-MS/MS test and critical-frozen specimen are required. Urine should be collected within 8 hours of dosing, and blood (serum/plasma) within 4 hours of dosing.

It is important to investigate the active components of any drug that a patient is prescribed or has otherwise administered when interpreting a positive drug test. There are dozens of different trade names and formulations of popular drugs that may contribute legitimately to a positive drug test. There are also some drugs that are recognized to cause analytical interference and may contribute to a false positive drug test. Examples of drugs that cause false positive results include cyclobenzaprine in tricyclic antidepressant drug screens, and phentermine in amphetamine drug screens. A complete pharmacy history, including non-prescription medication, is critical. Consult the laboratory for discussion of possible false positive drug test results.

Not usually. Most benzodiazepine immunoassays do not detect therapeutic concentrations of clonazepam or its common metabolite, 7-amino clonazepam. Quantitation by LC-MS/MS is the best methodology at ARUP for detection of clonazepam compliance. LC-MS/MS benzodiazepine panel (urine 0090358, serum/plasma 0093300), or clonazepam (serum/plasma 0090055).

No. However, these drugs can be detected with quantitation by LC-MS/MS in serum/plasma or urine. See test menu for ordering information.

The immunoassay screens for opiates detect (but not individually report) codeine, hydrocodone, hydromorphone, morphine and the heroin metabolite (6-acetylmorphine, or 6-AM, 6-MAM). In the reflex screens, oxycodone, oxymorphone are also reported as "opiates".

It is unlikely for passive inhalation of marijuana smoke to result in a positive urine test. While second hand smoke is a source of drug exposure, the amount of drug that is absorbed is far less than the amount of drug absorbed after deliberate, intentional drug use. Concentrations of marijuana metabolites in urine observed after exposure to second hand marijuana smoke are usually below the cutoff of both the screening test (15 – 20 ng/mL) and urine confirmation/quantitation test (5 ng/mL). Exceptions may exist particularly if there was significant/constant exposure. Consult references below:
- German/Dutch study involving passive cannabis exposure in a coffee shop: urine and blood
- German study: blood

The ARUP Drug Screen Cup is a CLIA-waived FDA-cleared point-of-care test device. It can be performed by technologists, technicians, as well as nonlaboratory personnel (minimum of high-school diploma required). For instance, a nurse or medical assisatant in a physician’s office may perform the point-of-care drug screen using the urine testing cup. Alternatively, urine can be sent to a central lab where the specimen is transferred into the testing cup and results are recorded.
Waived testing under CLIA requires the laboratory/facility to register the procedure and obtain a waived certificate. Requirements for proficiency testing, quality control procedures, and record keeping vary depending on the type of facility. If the CLIA-waived test is performed in a nonhospital setting, the responsibility for and management of testing should be through affiliation with a pathologist or laboratory director of a parent health care organization, or through a clinical consultant with comparable credentials (such as a registered med tech (MT) or a clinical laboratory scientist (CLS)).

We do not include buprenorphine in any of our immunoassay screens (whether for the point-of-care cup or for the lab tests), because of concern over the performance of commercially available reagents for this target. We have observed higher than acceptable levels of false positives and negatives. If buprenorphine is prescribed to the patient, the best strategy at this time is to order the quantitative buprenorphine test by LC-MS/MS at the same time a screen is ordered for the patient.

Adderall contains d-amphetamine and should therefore be detected by the amphetamine screens, provided that specimen is collected at an appropriate time after drug administration (please inquire if you need to discuss this further). Ritalin is methylphenidate and will not be detected unless the test for methylphenidate is specifically ordered.

A good way to evaluate elimination of marijuana is to normalize results to creatinine, and compare results for specimens collected at least one week apart. If a person has abstained from new use of marijuana, normalized concentrations should decrease over time. For further details, consult the following references:

- Schwilke EW, Gullberg RG, Darwin WD, Chiang CN, Cadet JL, Gorelick DA, Pope HG, Huestis MA. Differentiating new cannabis use from residual urinary cannabinoid excretion in chronic, daily cannabis users. Addiction. 2011 Mar;106(3):499-506.

- Smith ML, Barnes AJ, Huestis MA. Identifying new cannabis use with urine creatinine-normalized THCCOOH concentrations and time intervals between specimen collections. J Anal Toxicol. 2009 May;33(4):185-9.

To monitor compliance for methylphenidate or dexmethylphenidate, a quantitative LC-MS/MS test and critical-frozen specimen are required. Urine should be collected within 8 hours of dosing, and blood (serum/plasma) within 4 hours of dosing. Urine (2003115), and serum/plasma (2003114). These tests do not distinguish between d- and l- isomers of methylphenidate.

Quantitation by LC-MS/MS is the best methodology at ARUP for detection of clonazepam compliance. LC-MS/MS benzodiazepine panel (urine 0090358, serum/plasma 0093300), or clonazepam (serum/plasma 0090055).

Confirmation (which is usually a quantitative test) is important when actual concentrations for a specific drug or drug metabolite are required. For example, interpretation of opiate and benzodiazepine testing requires knowing what specific compound(s) are responsible for a positive result, and with what proportional relationship. Confirmation/quantitation is also preferred when the performance of available screening tests is poor. For example, if a screen is not very sensitive to the drug of interest, a false negative is likely; a quantitation test should be ordered instead. Screens are most useful when it is not known what the patient may have taken.

Order a quantitation test specific for the prescribed drug at the same time you order a screen panel. Many clients order the quantitation test for opiates and oxycodone (0090364) together with the urine screen panel (0090453). Quantitation of benzodiazepines and individual opioids are also commonly ordered together with the screen. If you wish to confirm every analyte that was screened positive automatically AND confirm the prescribed drug even if screened negative, order the quantitation test for the prescribed drug in addition to the screen-reflex test (0092186). If the prescribed drug was positive by the screen, the additional test will be canceled automatically to avoid duplicate testing.

No. Traditional drug abuse testing incorporates routine adulteration testing due to suspicions regarding donors trying to “beat” the drug test. Adulterants in traditional drug abuse testing may include specimen dilution, and additives such as nitrites or oxidants. However, in a pain management setting, the donor/patient is concerned about “passing” the drug test. Adulteration in a pain management population may involve the addition of drug (as powder or liquid) directly to urine specimens to mask the fact that the patient is not taking the drug as prescribed. This type of adulteration is best detected through targeted quantitative (confirmation) testing. Urine substitution is also a concern. Some substitutions can be detected by measuring creatinine or specific gravity. However, substitution with human urine (perhaps archived urine from the patient) cannot be detected by adulteration testing. When specimen adulteration is suspected, observed collections or blood testing is recommended. Adulteration of blood specimen is rare.

If more than one specimen is collected for an individual patient at the same time, those specimens can be combined to provide a larger testing volume. Mixing routine blood preservatives (such as EDTA and heparin) is not expected to interfere with drug testing.

When adulteration of the urine specimen is of concern, a blood specimen (serum or plasma) is often used. Also, a serum or plasma specimen is appropriate for patients on dialysis, for suspected cases of malabsorption (e.g. gastric bypass), and for evaluating other aspects of individual patient's pharmacokinetics.

Urine is preferred because drugs concentrate in the urine over time, which extends the time over which a drug may be detected. Urine is also non-invasive and inexpensive to collect and test, in most cases. Urine is, however, susceptible to adulteration or substitution by the donor. In contrast, both saliva (oral fluid) and blood are observed collections, thus lowering the likelihood of specimen adulteration or substitution. Saliva concentrations and the time course for detection more closely approximate blood (including serum/plasma) than urine. Of concern, however, is that not all drugs are represented in saliva. For example, opiates and amphetamines are observed in saliva, but benzodiazepines and barbiturates are not. Blood is the preferred specimen for correlating signs and symptoms with drug concentrations in a real-time acute setting. Hair is useful for demonstrating chronic exposure/use. Each centimeter of head hair represents approximately 1 month of time. Sampling errors, external contamination of the hair sample, efficiency of drug deposition into the specific type/color of hair, and laboratory performance limitations may compromise utility of hair for drug testing.

A serum or plasma specimen is appropriate for patients on dialysis, for suspected cases of malabsorption (e.g. gastric bypass), and for evaluating other aspects of individual patient's pharmacokinetics.

Yes, if you are using the testing cup supplied in the ARUP Drug Screen Kit. Transfer the urine from the cup into the tube included in the kit, and send to ARUP for quatitation/confirmation testing.