From analytical interference to the detection of intoxication

Area of Science:

• Clinical Chemistry
• Toxicology
• Nephrology

Background:

• Paracetamol (acetaminophen) overdose is a common clinical emergency.
• Accurate assessment of renal function is critical in paracetamol poisoning.
• Enzymatic creatinine assays are widely used but can be subject to interference.

Purpose of the Study:

• To report a case of undetectable creatinine levels due to paracetamol toxicity using an enzymatic method.
• To highlight the interference of paracetamol's toxic metabolite with enzymatic creatinine measurement.
• To emphasize the importance of using non-enzymatic methods for creatinine determination in paracetamol overdose.

Main Methods:

• Case report of a 66-year-old male presenting with decreased consciousness.
• Creatinine measurement in blood plasma using the Roche cobas c702® enzymatic method.
• Paracetamol concentration determination.
• Creatinine measurement using the Jaffe method for comparison.

Main Results:

• Enzymatic creatinine assay yielded undetectable levels.
• Toxic levels of paracetamol were confirmed in the patient's sample.
• The Jaffe method for creatinine determination showed no interference.

Conclusions:

• The toxic metabolite of paracetamol, N-acetyl-p-benzoquinone imine, interferes with enzymatic creatinine assays.
• Non-enzymatic creatinine methods (e.g., Jaffe) are more reliable in cases of paracetamol overdose.
• Accurate renal function assessment in paracetamol poisoning requires careful selection of creatinine measurement methods.