Aim: To evaluate urine integrity tests performed before illegal and abused substance analysis and to reveal their limitations.

Materials and Methods: This retrospective study was conducted between January 1, 2023 and June 15, 2023, in the AMATEM laboratory affiliated with Şanlıurfa Mehmet Akif İnan Training and Research Hospital.The results of substance analysis (amphetamine, ecstasy, benzodiazepine, cannabis, cocaine, opiate, heroin and synthetic cannabinoid-3) and urine integrity tests (creatinine, specific gravity, pH and nitrite) on 8858 urine samples belonging to 5495 people were examined.

Results: There were 116 diluted urine samples with urine creatinine values between 4.52-20 mg/dL, and 40 (34.5%) of them were positive for the substance. The number of samples with urine creatinine values between 200-400 mg/dL and above 400 mg/dL were 2915 and 141, respectively, and their substance positivity rates were 46.1% and 59.6%, respectively. There were 32 urine samples with urine specific gravity between 1.001-1.003 and 7 (21.9%) of them were positive for the substance. Substance positivity was detected in 223 (64.6%) of 345 urine samples with a urine specific gravity above 1.035.

Conclusion: These results showed that urine samples should be studied even if they are diluted, as diluted urine samples may have positive substance analysis results. Our findings also support that the creatinine and specific gravity criteria defined for adulterated urine samples in our national guide to be re-evaluated.