Urine Drug Screens

You should order a drug screen for any patient who has a substance use disorder, or whom you suspect may have one. Drug screens are the key diagnostic tests that help us determine what we are treating and whether our treatment is successful.

They are the only way to keep patients accountable for what they tell you, because substance-using patients are often ashamed of their use and hide the truth. Drug screening is not about “catching” or punishing patients. Instead, it’s a way to help establish honesty and accountability.

At a minimum, you should order drug screens in the following situations:
• Your patient has a current or recent substance use problem. This is the major reason to get a drug screen: monitoring the sobriety of patients who are acknowledged drug/alcohol users and want to get clean.
• Your patient has a remote substance use problem and you are considering prescribing a medication with potential for abuse.
• Your patient is not improving despite receiving evidence-based treatment, and you are wondering if drug use is interfering with treatment. The estimated lifetime prevalence of drug or alcohol abuse in depression is 16%–27%, in bipolar disorder 43%–56%, and in schizophrenia 20%–65%, depending on the study methodology used (Bradizza et al, 2006). The lifetime prevalence of drug abuse in the general population is around 8 (Compton et al, 2007), and around 18% for alcohol abuse (Hasin et al, 2007).
• You are prescribing a controlled substance medication (such as a psychostimulant or a benzodiazepine) and your patient has been requesting early refills or increased dosages.

WHICH TYPE OF SPECIMEN SHOULD YOU ORDER?
Specimens of urine, blood, hair, saliva, sweat, and even nails can be used to do lab drug testing. See Table 2-1 for more detail on types of drug tests.

Most clinicians will order only urine testing.

Available Drug Tests
Test Detection Time
Frame Notes
Urine 3–4 days Most commonly used
Blood 6–12 hours Can detect only recent drug use
Hair 7 days–3 months Expensive, but good for discovering use in more distant past
Saliva 24 hours Convenient; patients can’t adulterate or substitute; may not detect benzodiazepines
Sweat 7–14 days Patient can remove patch
Nails 7 days–3 months Not commonly ordered
Breathalyzer (for drugs: amphetamines, cocaine, marijuana, some opiates, and phencyclidine.
The comprehensive panel adds methadone (and sometimes other opiates) and sedative/hypnotic medications, such as benzodiazepines, barbiturates, and the “z-drugs” like zolpidem (Ambien) and zaleplon (Sonata).

Alcohol 7–12 hours
Alcohol metabolites, ethyl glucuronide
and ethyl sulfate (ETG/ETS) 3–4 days
Amphetamine/methamphetamine 1–2 days
Barbiturates 2–4 days (2–3 weeks for long-acting phenobarbital)
Benzodiazepines 24 hours (short-acting); 2–4 days (longacting); > 7 days for chlordiazepoxide, diazepam
Cocaine 6–8 hours (2–4 days for benzoylecgonine metabolite) LSD 2–4 days
Marijuana 3 days for single use; 5–7 days for moderate use (4x/week); 10–15 days for daily use; > 30 days for long-term heavy use MDMA 1–2 days Nicotine 12 hours Opioids
• Codeine
• Buprenorphine
• Heroin, hydromorphone, morphine, oxycodone
• Methadone
1–2 days
2–3 days (5–7 days metabolites)
2–4 days
2–3 days; 7–9 days for chronic use
PCP 2–8 days; up to 30 days for chronic use

Alcohol is not usually part of urine drug testing because it is only detectable in the urine for a very short time—around 9 hours—depending on
the quantity and chronicity of alcohol consumption. Blood or breath alcohol testing give a better idea of a person’s alcohol level, but the window of detection is shorter. With the various labs and collection methods, it can be difficult to decide which test to order for which patient.

Here’s my bottom-line advice:
• If you have no collection facility at your office, I suggest working with

Urine Testing Detection Periods by Drug
Drug Detection Period for Urine Testing
Alcohol 7–12 hours
Alcohol metabolites, ethyl glucuronide and ethyl sulfate (ETG/ETS) 3–4 days
Amphetamine/methamphetamine 1–2 days
Barbiturates 2–4 days (2–3 weeks for long-acting phenobarbital)
Benzodiazepines 24 hours (short-acting); 2–4 days (longacting); > 7 days for chlordiazepoxide, diazepam
Cocaine 6–8 hours (2–4 days for benzoylecgonine metabolite) LSD 2–4 days
Marijuana 3 days for single use; 5–7 days for moderate use (4x/week); 10–15 days for daily use; > 30 days for long-term heavy
use MDMA 1–2 days Nicotine 12 hours
Opioids
• Codeine
• Buprenorphine
• Heroin, hydromorphone, morphine, oxycodone
• Methadone
1–2 days
2–3 days (5–7 days metabolites)
2–4 days
2–3 days; 7–9 days for chronic use
PCP 2–8 days; up to 30 days for chronic use

one or more local lab collection sites. Large national laboratory service companies such as LabCorp or Quest Diagnostics have multiple collection sites in many areas and are usually set up to do urine collection for drug testing. Which lab(s) you send patients to will often depend on the individual patient’s health insurance. Just fill out a lab order requisition (available online or through an electronic health record system) and give it to the patient or send it to the lab.
• If you have a collection facility, the on-site lab can often help you determine what tests to order.

Blood
Blood sampling is an accurate way of determining how much of a drug is in a patient’s system, but its detection window is only 6–12 hours, so it’s hard to use for random screens unless you can draw the sample in your office.

Hair
Hair analysis gives you a much wider detection window (up to 90 days) and is an easy and noninvasive collection method. However, it won’t tell you about your patient’s current substance use (it doesn’t detect use within the previous 7–10 days), and it can’t detect alcohol use. Other limitations of hair testing include difficulty in detecting low-level (single-time) use, and potential inaccuracy depending on your patient’s hair color (some drugs have enhanced binding to melanin in dark hair). While it’s hard to adulterate a hair sample, some patients may bleach their hair or shave their head to avoid this kind of testing; if so, hair on any other part of the body can be used.

Saliva
A quick swab of the inner cheek provides easy collection for saliva, which can be used to detect traces of drugs and alcohol. Oral fluid testing is comparable to urine testing and is less invasive; it’s also harder for patients to adulterate or substitute. However, not all labs are equipped to test this type of sample.

Sweat
A skin patch that looks like a large adhesive bandage can be worn by patients for up to 7–14 days to measure drugs in their sweat. This has become a popular way for parole programs to monitor drug use. It’s noninvasive, easily administered, and hard to adulterate (unless the patient removes the patch). This method is limited by the availability of testing facilities; it’s also not entirely clear whether its results are affected by how much a person sweats.

Commercial manufacturers have developed several wearable detection devices to monitor blood alcohol level; these are primarily aimed at consumers who are worried about getting a DUI, so they can plan to limit their alcohol consumption or find a ride home. Nails Drug testing from nails is rare compared to testing of urine, hair, or oral fluid. Similar to hair testing, nail testing has a long window of detection. However, not many labs test nails, and there is insufficient scientific data tosupport its routine use. Other limitations include the risk of environmental contamination of nails for some drug classes; nail testing also cannot detect alcohol.

Breath
Not every clinic needs an alcohol breathalyzer, but it can be helpful if you think your patient has been drinking and you need to consider safety issues (such as whether the patient should drive).

The patient blows into a breathalyzer device, which returns a number representing the patient’s blood alcohol concentration. A breathalyzer’s detection window is similar to blood testing (6–12 hours), but varies depending on the amount of alcohol consumed over time. Some court systems mandate alcohol breathalyzer ignition interlocks for the vehicles of DUI offenders, which prevent the car from being started if the breath alcohol
level is too high. alcohol only)
A few hours Often used by patient’s family to assess driving safety

Urine
Urine drug testing is the most common test ordered because it’s noninvasive, it’s available in large volume, and it generally has high concentrations of drugs and metabolites (allowing for a longer detection time frame than in blood, for example). Many factors can affect how soon and for how long a drug can be detected, but you can make reasonable predictions. It takes about 2–3 hours for most drugs to be concentrated in urine (only 30 minutes for alcohol), so testing too soon after use in a non-chronic user of a drug may give you a negative result. Most drugs will be detected in urine for about 2–4 days after use; some will be detected for longer (see Table 2-2 for urine testing detection windows). Although labs vary, there are two common urine drug screening panels that you can order: basic and comprehensive. The basic test screens for 5

Benzodiazepines
Not all benzodiazepines are detected on drug screens. Alprazolam and diazepam, the most commonly misused benzodiazepines, are reliably detected. Lorazepam and chlordiazepoxide are sporadically detected, and clonazepam is often not picked up. Sometimes when I see unexpected
positive results for benzodiazepines, the patients are legitimately receiving the medications from another doctor and do not realize they are potentially abusable. I make sure they recognize the issue, and this usually offers a teaching opportunity about the disadvantages of taking a benzodiazepine while struggling with recovery from another drug.

Stimulants
Some OTC preparations can cause false positives for stimulants, such as pseudoephedrine, but a patient will have had to ingest several boxes of it to produce a false positive. Vicks VapoInhaler is an OTC product in a plastic lipstick-size tube that contains levo-methamphetamine (a racemic isomer of methamphetamine that is not psychoactive), which can cause a false positive result for amphetamines. The cocaine assay is very reliable—there are very few false positives, and it doesn’t cross-react with lidocaine or Novocaine.

Phencyclidine
Phencyclidine (PCP) false positives are possible from dextromethorphan in OTC cough medications, and from some antipsychotics. False negatives False negatives are more common than false positives, since patients who are continuing to use despite treatment have a strong incentive to be creative in efforts to mask their use—and there is a robust internet-based industry catering to this market (see Table 2-4).
The most common way of achieving a false negative is water loading, which I discussed earlier. There are various other readily available substances that can be used to adulterate a urine sample. For example, patients can add table salt to a sample, which can be effective, but if they add too
much it can precipitate out and make the effort obvious.

Vinegar will mask THC testing, but it lowers the pH of the urine sample, which will be picked up on dipstick testing or by the lab in more formal testing. Other specialized adulterants are available on the internet, usually selling for about $19.99 per use. Some labs will test for the more common adulterants like glutaraldehyde. The marketing for these products can be amusing.

For example, the product “Urine Luck” hired Tommy Chong (from Cheech TABLE 2-4. False Negatives on Drug Screens Potential Cause of False Negative Drugs Masked Notes Visine OTC eye drops (tetrahydrozoline) THC benzodiazepines Visine is squirted into urine cup (squirting in eyes is not effective for urine) Drano or laundry bleach (sodium hypochlorite) amphetamine barbiturates benzodiazepines cocaine opiates THC Increases pH, but may cause visible foam in urine Vinegar (acetic acid) THC Lowers pH of urine sample Ammonia multiple, depends on assay Increases pH, has characteristic smell Table salt (sodium chloride) amphetamine barbiturate cocaine opiates THC Increases specific gravity of urine sample (>1.035), may precipitate out Hydrogen peroxide THC opiates LSD May cause bubbles in urine Liquid hand soap multiple, depends on assay May cause bubbles or make urine cloudy Glutaraldehyde (UrinAid) cocaine amphetamine barbiturates benzodiazepines opiates THC Internet purchase, some labs may test for this adulterant Pyridinium chlorochromate (Urine Luck) opiates THC Internet purchase Potassium nitrite (Klear, Whizzies) THC Internet purchase  to deliver the memorable slogan, “When you’re caught with your pants down, Urine Luck.”