What is validity testing?

Specimen validity testing is used to determine whether:

1. Certain adulterants or foreign substances were added to the specimen;
2. A urine specimen was diluted; or
3. The specimen was substituted.

Urine specimens

A laboratory that conducts validity testing on a urine specimen must follow certain, specific procedures including:

• Testing the specimen for creatinine,
• Determining the specimen’s specific gravity if the creatinine concentration is less than 20 mg/dL,
• Measuring the specimen’s pH, and
• Testing for substances that may be used to adulterate the specimen.

A specimen is considered dilute if the creatinine concentration is less than 20 mg/dL and the specific gravity is less than 1.003.

A specimen is considered substituted if the creatinine concentration is less than or equal to 5 mg/dL and the specific gravity is less than or equal to 1.001 or greater than or equal to 1.020.

A specimen is considered adulterated if it is determined that:

• A substance that is not expected to be present in human urine is identified in that specimen,
• A substance that is expected to be present in human urine is identified at a concentration so high that it is not consistent with human urine, or
• The physical characteristics of the specimen are outside the normal expected range of human urine.

Oral-fluid (saliva) specimens

Specimen validity testing is the evaluation of the specimen to determine if it is consistent with normal human oral fluid. The purpose of validity testing is to determine whether certain adulterants or foreign substances were added to the oral fluid, if the oral fluid was altered.

If a specimen exhibits abnormal characteristics (e.g., unusual odor or color), causes reactions or responses characteristic of an adulterant during initial or confirmatory drug tests, or contains an unidentified substance that interferes with the confirmatory analysis, then the lab may conduct validity testing.

If the lab determines that the specimen is invalid and Health and Human Services (HHS) guidelines direct the lab to contact the MRO, the MRO and the lab and together decide if testing the primary specimen by another HHS-certified lab would be useful in being able to report a positive or adulterated test result.