From analytical interference to the detection of intoxication.

This article describes the case of a 66-year-old man who attended the emergency department due to a decrease in the level of consciousness. When determining creatinine in blood plasma using the enzymatic method on the Roche cobas c702® (Roche Diagnostics, Manheim, Germany), an undetectable creatinine value was obtained. Recently, both the literature and the manufacturer of the assay have described that the toxic metabolite of paracetamol, N-acetyl-p-benzoquinone imine, interferes with the enzymatic measurement of creatinine. Therefore, the concentration of paracetamol was determined in the same sample confirming toxic levels. On the other hand, the determination of creatinine by the Jaffe method did not present such interference. This case underlines the importance of determining creatinine by non-enzymatic methods in cases of paracetamol overdose in order to correctly assess renal function.