Detection of ingested nitromethane and reliable creatinine assessment using multiple common analytical methods.

Aim: Nitromethane, found in fuels used for short distance racing, model cars, and model airplanes, produces a falsely elevated serum creatinine with standard creatinine analysis via the Jaffé method. Erroneous creatinine elevation often triggers extensive testing, leads to inaccurate diagnoses, and delayed or inappropriate medical interventions. Multiple reports in the literature identify "enzymatic assays" as an alternative method to detect the true value of creatinine, but this ambiguity does not help providers translate what type of enzymatic assay testing can be done in real time to determine if there is indeed false elevation.

Methods: We report seven cases of ingested nitromethane where creatinine was determined via Beckman Coulter analyser using the Jaffé method, Vitros analyser, or i-Stat point-of-care testing. Nitromethane was detected and semi-quantified using a common clinical toxic alcohol analysis method, and quantified by headspace-gas chromatography-mass spectrometry.

Results: When creatinine was determined using i-Stat point-of-care testing or a Vitros analyser, levels were within the normal range. Comparatively, all initial creatinine levels obtained via the Jaffé method were elevated. Nitromethane concentrations ranged from 42 to 310 μg/mL.

Conclusions: These cases demonstrate reliable assessment of creatinine through other enzymatic methods using a Vitros analyser or i-STAT. Additionally, nitromethane is detectable and quantifiable using routine alcohols gas chromatography analysis and by headspace-gas chromatography-mass spectrometry.