Specimen validity testing (SVT) is performed on a urine drug screen specimen to detect substitution, adulteration, or dilution. See the Drugs of Abuse Reference Guide for additional information on SVT. Use of a Medical Review Officer is recommended to evaluate out of range SVT results.
- Substitution - Submission of a specimen that is not characteristic of human urine. Typically, this may be water or water with salt in it and is identified by extreme creatinine and specific gravity results.
- Adulteration - Adding a substance to a specimen after it has been collected. The product added is designed to mask the presence of, or chemically destroy, the drug or drug metabolite that the specimen may contain. An adulterant product may be added with the intention of adversely affecting the testing reagents.
- Dilution - Result of ingestion of large amounts of water typically just before urine donation or as a result of physiological conditions. If drug/metabolites are diluted to a concentration below the initial test cutoff, a dilute urine may result in a false negative.