Implications of unexpectedly detectable methanol in patients presenting to an urban emergency department

Methanol is ubiquitous, and early intoxication mimics other conditions. The prevalence of occult methanol intoxication is unknown. The goal of this study is to determine the frequency of unexpectedly positive methanol concentrations in patients at an urban safety net hospital with real-time testing capabilities, and to evaluate the clinical significance of these findings.

This was a retrospective cohort study of patients with detectable methanol concentrations presenting to an emergency department from 2015 to 2022. Dual column, dual flame ionization detection utilizing headspace sampling with gas chromatography is available 24 h/day. Ethanol and methanol concentrations result in tandem when either test is performed. For safety reasons, a positive methanol result triggers a reflex order to report the information in the electronic medical record. We reported descriptive statistics for cases of detectable methanol concentrations and compared expected and unexpected positive concentrations.

Orders for 20,666 ethanol and 1,868 methanol concentrations were identified; methanol results were positive in 101 (6%) cases. Twenty-eight represented repeated testing during one patient's hospitalization. The median methanol concentration among the remaining 73 patients (30.1% female) was 60 mg/L (IQR: 50-70 mg/L; range 50-5,000 mg/L). There were 26 expected (median methanol concentration 80 mg/L [IQR: 60-290 mg/L]) and 47 unexpected (median methanol concentration 50 mg/L [IQR: 50-60 mg/L]) positive methanol assays during the study period (Mann-Whitney U-test, P <0.001). No patients with incidentally positive methanol required directed therapies.

Unexpectedly positive methanol concentrations in this study population were uncommon and without clinical significance, in that none required specific treatments or directed therapies.

Our data suggest that history and clinical suspicion are likely sufficient to detect clinically important methanol exposures. Occult methanol exposures of clinical significance appear unlikely when clinical suspicion is low.