Potential Adulteration or Excessive Dilution of Samples

Potential Adulteration or Excessive Dilution of Samples

Workplace drug testing provides information to employers about potential drug use of their employees.  It is meant to act as a deterrent for drug use in the workplace. Urine is one of the specimen types collected for drug testing.  The employee provides a urine specimen at a collection site under chain-of-custody to ensure the specimen is actually the donor’s specimen. The collector follows established protocol to collect the specimen, reducing the potential for the donor to adulterate the specimen (i.e., add a something to the specimen).  

At Vanguard Lab Sciences, we test for possible adulteration or excessive dilution of the urine specimen by performing Specimen Validity Testing (SVT).  These tests are Creatinine, Specific Gravity, pH, and Oxidant. The following chart lists the Expected Ranges for each of the SVT tests and possible reasons for a specimen to be outside the Expected Range.

 

Test Expected Range Possible Reason for Specimen Result to be Outside Range
Creatinine 20 – 500 mg/dL 0:  specimen not human urine;           possible substituted
<2:    possible excessive dilute
<20:  possible dilute
>500: highly concentrated urine
Specific Gravity 1.003 – 1.035 1.000:   specimen not human urine; possible substituted
<1.003:  possible dilute
>1.035:  highly concentrated urine
pH 4.7 – 7.8 <4.7:  possible adulterated;

>7.8:  possible adulterated

Oxidant < 200 µg/mL ≥200: possible adulterated

 

For a specimen that has a creatinine of 0 and a specific gravity of 1.000, the specimen is not human urine.  A voided urine specimen from a live person would have a detectable creatinine and specific gravity. These values are seen if water has been substituted for the urine specimen.  A specimen with a creatinine value <2 and a specific gravity <1.003, may indicate excessive dilution of the specimen. The donor may be drinking lots of water, or may have added water to the urine specimen.  A specimen with a creatinine value <20 but >2 and a specific gravity >1.003 may indicate dilution of the specimen. The donor may be drinking lots of water, or may have added some water to the urine specimen.  A specimen with a creatinine value >500 or a specific gravity value of >1.035 indicates a highly concentrated urine; the donor may not be drinking enough water, or may have a kidney disease. None of these scenarios affect the analytical methods used by the laboratory to identify drugs in the urine.  However, possible dilute or possible substituted specimens may have drug concentrations in the urine that are below the laboratory’s cutoff levels and be reported as negative.

For a specimen with pH values outside the expected range, the specimen may be possible adulterated.  A specimen with a pH outside the expected range does not affect the analytical methods used by the laboratory to identify drugs in the urine.

For a specimen with an Oxidant value outside the expected range, the specimen may be possible adulterated.  The donor may have added a substance to the provided urine. A specimen with an Oxidant value outside the expected range does not affect the analytical methods used by the laboratory to identify drugs in the urine.