Kreatininkoncentrationen i urin bör mätas vid drogtestning. Riktlinjer för beslutsgräns och tolkning behövs - inte minst för rättssäkerheten
Sammanfattning
Sample adulteration and substitution as ways to avoid detection are a constant concern in urine drug testing. Creatinine measurement is a common method to identify dilute urine samples that may cause false negative results. In Swedish laboratories, the lower creatinine threshold employed to indicate a dilute specimen currently ranges from 2.0–4.4 mmol/l. Given the severe implications of a positive drug test, and the risk for different legal consequences due to the variable creatinine cutoff values applied, a national harmonization of urinary creatinine measurement is warranted. Based on a meta-analysis of data compiled from four major Swedish laboratories, the recommended cutoff value for a urine sample to be considered dilute is 2.0 mmol/l, thereby adapting to international guidelines. However, it should be noted that a dilute urine specimen does not necessarily imply deliberate sample manipulation.