The nitrite or oxidant threshold level established by the federal government is 200 mg/mL. This is based on the level at which a drug screen may be impacted by this type of adulterant and is higher than what would be expected from normal physiological processes. Nitrites or other oxidants > = 200 mg/mL are reported as “Invalid”. Specimens with nitrite levels > = 500 mg/mL are reported as “Adulterated”.
At a minimum, the SVT panel includes testing for creatinine; a creatinine < 20 mg/dL reflexes to a specific gravity test. Results of both creatinine and specific gravity are used to identify dilute, substituted or invalid specimens. Tests for pH and nitrite can also be added to a panel, and are used to assess whether the physiological parameters of the collected specimen are in the expected range.
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.
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.