Q: What is specimen validity testing?
A: Specimen validity testing (SVT) is performed on a drug screen specimen to detect substitution, adulteration, or dilution. See the Drugs of Abuse Reference Guide for additional information on SVT.
- 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. Specimens meeting dilute specifications typically are not considered questionable donations.
Q: Does the lab conduct SVT before screening for drugs?
A: No, specimen validity testing is performed simultaneously with the initial drug screens. Depending upon the drug screen and the specimen validity results, the laboratory will release (1) both the drug screen and the specimen validity test results, (2) the specimen validity test results only, or (3) the drug screen results only.
Q: Is the nitrite test threshold based on body functions, or does it allow for infection, food ingestion with high nitrates, and water consumption with high nitrites?
A: The nitrite threshold level established by the Federal Government is 500ug/mL. This is based on the level at which a drug screen may be impacted by this adulterant and by which no normal physiological level has been detected.
Q: How would a drug test be evaluated when nitrates are 490 ng/mL?
A: The nitrite result would be negative, as this level would not interfere with our testing process. The drug test(s) ordered would be conducted and reported following standard operating procedures.