The number on a urine drug test indicates if the test is positive or negative, according to Healthline. Immunoassay urine drug tests measure in nanograms per milliliter with a cut-off point. The exact meaning of the numbers on a urine drug test depends on the type of test.
The immunoassay urine drug test does not measure the kind of used drugs, but, rather, how the body forms antigen-antibody complexes that normally get interrupted by drug usage, notes Healthline. Rather than showing the number on a urine drug test, most test labs show a negative or positive read-out, or use a strip that turns color. Urine drug test screen for drugs and alcohol.