Urine is the most commonly used specimen for drugs of abuse testing. This is primarily because urine is readily available in large quantities and contains high concentrations of parent drugs and metabolites. It is hence, an accepted way of testing for specimen validity when monitoring for abused drugs whether within the workplace, criminal justice system (e.g. drug courts) or for compliance.1 In general, human urine reflects drugs consumed within the past several days depending on drug use.
Despite all the benefits and ease in testing urine specimens, urine samples are extremely susceptible to tampering1, making it tempting for participants to either use adulterants or dilute their urine. In addition to performing specimen validity testing, collectors should also check temperature and visually inspect the specimen for color and viscosity to assess possibility of adulteration. Urine samples are adulterated in order to obtain a false negative result by the patient or participant. Testing for adulterants assures validation of negative results and confirms sample validity.
Specimen validity tests (SVT) are methods used on a urine drug screen specimen to detect for substitution, adulteration, or dilution. Thermo Fisher Scientific provides Specimen Validity Tests for creatinine, specific gravity, oxidizing agents (e.g. nitrites) and pH.
Testing participant samples every time using multiple Specimen Validity Tests allows you to create a historical map of the expected “normal” results for a particular participant. A deviation from the normal parameters is evidence of dilution or adulteration. For problematic participants with a history of relapse, urine specimens should be routinely tracked using various specimen validity tests. Doing so allows drug testing facilities to track participants and creates a powerful tool to help confront denial. At the end, testing urine samples for specimen validity ensures for a more effective drug monitoring program.
Drug concentrations in urine can be influenced by dilution (drinking large amounts of water) or dehydration. Creatinine levels in the urine are a good indicator of this phenomena.2,3 The higher the creatinine, the more concentrated the urine and vice versa. Creatinine Adjustment, also referred to as Creatinine Normalization, is used to normalize the creatinine concentration of urine to an expected average creatinine concentration.
Download our SmartNotes brochure to learn more about Specimen Validity Testing.