Illicit drug abuse remains a serious public health issue, and with it comes the potential for users to try to cheat on drug tests. Writing in a mini-review in CLN’s February issue, Dr. Amitava Dasgupta says people try to cheat drug testing in three different ways: substituting their urine with synthetic urine or drug-free urine purchased from a clandestine source; drinking a commercially available product to flush out drugs; or adding an adulterant in vitro to the urine specimen after collection. Synthetic urine is difficult to detect because it has similar pH, creatinine, and specific gravity to normal urine. Specific tests are needed to identify compounds that are normal constituents of human urine but not found in synthetic urine, such as cortisol.

Dasgupta is a professor of pathology and laboratory medicine at the University of Texas-Houston Medical School. He is the medical director of laboratory services of TIRR-Memorial Hospital as well as director of clinical chemistry and point of care testing at Memorial-Hermann Hospital in Houston.

Commercially available products that adulterate urine or flush out drugs can be classified under two broad categories. The first includes fluids or tablets that, along with drinking large amounts of water, dilute urine. Common products are Absolute Detox XXL drink, Absolute Carbo Drinks, Ready Clean Drug Detox Drink, Fast Flush Capsules, and Ready Clean Gel Capsules.

The second category of products is in vitro urinary adulterants that are added to urine after collection. Examples include Stealth (peroxidase and peroxide), Klear (nitrite), Clean ADD-IT-ive (glutaraldehyde) and Urine Luck (pyridinium chlorochromate, (PCC). In addition, iodine is a strong oxidizing agent and may potentially destroy abused drugs, especially marijuana metabolites. Research also indicates that papain with intrinsic ester hydrolysis ability could significantly reduce the concentration of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH), a metabolite of marijuana, if added to the urine specimen in vitro.

Would-be drug test cheaters might also try adulterating their specimens with household chemicals, but most can be detected by specimen integrity testing. Both collection sites and laboratories have at their disposal a number of mechanisms to detect potentially invalid specimens. The temperature, for instance, should be within 90.5–98.9°F. The specific gravity should be between 1.005–1.030, and pH should be between 4.0–10.0. The creatinine concentration should be 20–400 mg/dL. However, some drug testing laboratories consider a creatinine concentration of 15 mg/dL as the lower-end cutoff. One common adulterant, sodium chloride, always produces a specific gravity greater than 1.035 if added at a concentration necessary to produce a false-negative result.

However, specimen integrity testing doesn’t detect all adulterants. For example, it won’t pick up adulteration of urine with Visine eye drops, isopropanol, or other urinary adulterants, but effective spot tests and special urine dipsticks are available.

Pick up the February issue of CLN to read more about methods used to detect attempts to cheat on drug tests.