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Industry News: Why Is Creatinine Being Analyzed in Urine Drug Tests?

Published on: September 8, 2016

Written by: Confirm BioSciences.

The accuracy and reliability of urine drug test results depend heavily on the validity the urine specimen. When the specimen is pure and is free from adulteration or substitution, those who rely on the results of the analysis can be assured that that the reported outcome is precise.

Drug Test Adulteration

Adulteration or tampering with the specimen in order to alter the drug test results to produce a false negative is a known practice among drug users. A common way to do is by adding some products such as bleaching agents or detergents to the urine sample. Another is by concealing the metabolites or by-products of the ingested drugs by consuming excessive amounts of fluids or taking diuretics in an attempt to “flush” out the metabolites and “dilute” the urine.


See Also: Why Synthetic Urine Won’t Work 


The best way to check for “dilution” is to analyze some urinary characteristics such as creatinine levels. Creatinine is a waste product of creatine, an amino-acid contained in muscle tissue and found in urine. It is filtered out of the blood by the kidneys and some amounts are normally secreted into the urine.  Normal ranges are 0.5 to 1.0 mg/dl for women and 0.7 to 1.2 mg/dl for men. Below normal creatinine levels indicate that a person has been drinking excess fluids. Such a reading is a red flag in drug tests because it signifies that the person tested has attempted to tamper with the results by disguising other active by-products that would have otherwise been detected. When a result comes back negative in a situation like this, it would be referred to as a “Negative Dilute”.

In other words, the creatinine levels determine whether or not a person is trying to cheat a drug test. Most laboratories now perform advanced screening procedures that verify whether there has been adulteration or dilution. In the case of the latter, when the urine sample is too diluted, the results are normally labelled as “inconclusive.”

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