Urine Drug Testing

Generally, screen test results will become available within 3 business days of the sample’s receipt at the lab. If confirmation tests are requested, these results will be available within 5 business days of the sample’s receipt at the lab. The Lab will communicate with partners in the case of prolonged delays.

Please contact the Urine Drug Program with any needs for expedited test results, every effort will be made to accommodate these requests.

Adulteration is the tampering of a urine specimen with the intention of altering drug test results. The use of adulterants can cause false negative results in drug tests by either interfering with the screening test and/or destroying the drug metabolites present in urine.

Urine adulteration can be performed in several ways:

• Drinking excessive amounts of water before a urine drug test

• Submitting “synthetic urine” from a foreign donor

• Adding a substance to the urine during the collection process

• Dilution using sink or toilet bowl water

A notation of possible adulteration on the test report could indicate creatinine, pH or specific gravity outside of the acceptable range.

• The accepted method to test for adulteration or dilution is to measure the creatinine level, specific gravity, and the pH level of the urine sample. Although the laboratory is unable to determine the cause/intent of irregular adulteration test results, out-of-range measurements may indicate an attempt by the client to alter the outcome of the urine drug screening process. 

• If laboratory results indicate abnormal creatinine, specific gravity and/or pH levels, further panel testing is conducted to detect the addition to the urine sample of chromate, halogens (bleach), nitrite and/or oxidants (commercially available adulterants which can cause false negative results in drug tests). 

Please note: Additional adulterant panel tests are only included on the Patient Test Results report if an adulterant is determined “present” in the sample.

Creatinine is a breakdown product of creatinine phosphate in muscle and is usually produced at a fairly constant rate by the body. The amount of creatinine in a sample indicates the dilution level of the specimen as well as whether the sample is actually urine.

Creatinine levels above 20 mg/dL are within normal range. Specimens with a creatinine level of less than 20 mg/dL are considered to be dilute and indicate “Possible Adulteration of Sample.”  Drinking large quantities of water or other liquids (known as “flushing”) may dilute the urine enough to create a negative drug test. Furthermore, the absence of creatinine (less than 5 mg/dL) is indicative of a specimen not consistent with human urine.

The Specific Gravity test measures the dilution level of a urine sample. It is a measurement of the weight of a drop of urine relative to the weight of a drop of water (water has a specific gravity of 1.000). The specific gravity of unadulterated human urine should fall between 1.005 to 1.030. Values less than 1.005 indicate sample dilution, either by drinking large quantities of water or other liquids or by directly adding water or other liquids to the urine sample post collection. For specific gravity values greater than 1.030, the interpretation can be more ambiguous. A heavier than normal specific gravity can possibly come from a medical issue, such as bladder infection (bacteria in the urine which causes excess sedimentation), or from the addition of an adulterant.

The pH test measures for the presence of acidic or alkaline adulterants in urine. Normal urine pH levels should range from 4.5 to 8.0. Once collected, urine generally becomes more alkaline over time and a fluctuation in urine pH to a value greater than 8.0 will not affect urine drug test results. However, the lower the pH of a specimen (less than 4.5), the greater the likelihood that someone adulterated the specimen to make it more acidic. A person would have great difficulty passing a highly acidic specimen due to extreme burning and bladder irritation caused by the acidity.

• Screening and confirmation testing are performed using different testing methodologies that have different specificities and sensitivities. In general, screens allow us to determine what classes of drugs are present in the sample while confirmations allow us to report exactly which drug and how much of that specific drug is present. It is generally recommended that positive screen results be confirmed with additional GC/MS or LC/MS/MS testing.

• The immunoassay tests used to perform initial drug screening are designed to detect a wide range of chemically similar compounds that react with targeted antibodies. The combined cross-reactivity of compounds in the drug class may produce a positive response, even though an individual metabolite may be present below the initial test cutoff.

• When performing confirmation testing by GC/MS or LC/MS/MS, one or more specific metabolites can be identified, quantified and reported using the applicable confirmation cutoff for a positive test result.

• Confirmation tests can be ordered on the Urine Drug Test Request Form that accompanies the urine sample to the lab. Check the boxes next to the drugs you wish to have confirmed in the bottom right “Urine Drug Confirmation Analysis Requested” section. If confirmation tests are ordered on the initial requisition, a positive screen result will automatically trigger a confirmation test.  Negative screen results are not routinely confirmed.

• If you did not request confirmations on the initial Urine Drug Test Request Form but would like to have confirmation tests added to the analysis, please email your request to [email protected]. In your request, please include your name, the client’s name, and the drug(s) you wish to have confirmed.

• Although CBD is a chemical found in cannabis, tetrahydrocannabinol (THC) is the intoxicating component of the drug. By law CBD products may be comprised of only up to 0.3% THC. 

• While pure CBD generally does not produce false positives on THC drug screens, many largely unregulated CBD products can be contaminated with levels of THC greater than 0.3% and may lead to variable screen results. 

• Additionally, many CBD products may contain cannabinol (CBN), a derivative of THC which can react with drug tests and cause a false positive result.  A confirmatory test is recommended to definitively distinguish THC from CBD and CBN.

• Benzoylecgonine is the main metabolite of cocaine and therefore the target compound in urine drug screens and confirmations. If benzoylecgonine is detected in a urine sample, the client cannot claim that the result is a false positive due to Novocaine or any other "-caine" type of drug. Benzoylecgonine is only found in nature as a metabolite of cocaine, and there would be no other valid reason for it to be present in a urine sample.  

• Although our screen test is very analyte specific for benzoylecgonine, confirmatory testing with LC/MS/MS can further identify the cocaine metabolite in a sample and conclusively eliminate the possibility of a false positive result.