What is specimen validity testing (SVT)?

Specimen validity testing (SVT) often called testing for nitrates or Test Sure (TS) is is performed on a drug screen specimen to detect substitution, adulteration, or dilution.

  • 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.  Adulterants are foreign substances either ingested or added directly to a urine specimen to prevent the detection of drug use. Promoted as "cleansing agents," these substances range from everyday household items to specific chemical additives easily obtained through the Internet
  • 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.  Donors sometimes attempt to drink large quantities of  fluids in an attempt to dilute their urine. By measuring and reporting creatinine and specific gravity, the lab and our medical review officer (mro) will have additional information to assess the validity of the urine specimen.

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.

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.  

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.

At Quest Diagnostics, TestSure adulterant testing helps to ensure that your donor's urine sample has not been adulterated. When you request TestSure, Quest will screen the specimen for a variety of compounds by using state-of-the-art secondary testing methods. The results are then provided to the medical review officer (MRO) for interpretation.