Abstract
Background
Relying on a treatment threshold for methanol poisoning of 20 mg/dL (6.2 mmol/L) as
a stand-alone criterion may lead to unnecessary and invasive treatment because it
is likely too conservative, especially for patients with repeated, intentional methanol
exposures.
Objective
We investigated how often patients with recurrent intentional methanol exposures above
this threshold developed biochemical or overt clinical toxicity despite not being
treated with either an alcohol dehydrogenase inhibitor (ADHi) or hemodialysis.
Methods
We identified patients with ≥3 methanol-related emergency visits from 2002 to 2015
and selected every visit in which neither ADHi nor hemodialysis were administered
despite serum methanol >20 mg/dL but neither metabolic acidosis nor end organ toxicity
at presentation. The primary outcome was the incidence of visual deterioration or
death.
Results
Four patients accounted for the 17 visits that met inclusion criteria. All exposures
were intentional substance misuse, and 7 of 17 were via inhalation (i.e., huffing).
Initial methanol concentrations ranged from 22 mg/dL to 35 mg/dL (7–11 mmol/L). Four
of these 17 visits had undetectable initial ethanol concentrations at presentation,
including 1 with an initial methanol concentration of 35 mg/dL. No patients developed
visual deterioration, and all were known to have survived the exposure.
Conclusion
Following recurrent, intentional methanol exposure, isolated serum methanol concentrations
as high as 35 mg/dL (11 mmol/L) appear to be well-tolerated without treatment in the
absence of metabolic acidosis or end-organ toxicity. To better define the methanol
treatment threshold, prospective studies are warranted in which patients are followed
closely while fomepizole is withheld.
Keywords
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Article info
Publication history
Published online: April 16, 2020
Accepted:
March 18,
2020
Received in revised form:
February 28,
2020
Received:
November 8,
2019
Footnotes
Reprints are not available from the authors.
Identification
Copyright
© 2020 Elsevier Inc. All rights reserved.
