# Beyond lactate: prognostic value of metabolic and biochemical parameters in methanol poisoning - a retrospective observational study

## TL;DR

This study shows that lactate levels and metabolic markers in the emergency department can predict outcomes in methanol poisoning, helping guide early treatment decisions.

## Contribution

The study introduces lactate clearance and anion gap as novel prognostic tools for methanol poisoning in the emergency department.

## Key findings

- High admission lactate and poor lactate clearance strongly predict mortality in methanol poisoning.
- Anion gap and base excess help predict ICU admission and discharge outcomes.
- Early metabolic markers can improve risk stratification and management decisions in the ED.

## Abstract

Methanol poisoning carries high mortality and morbidity, and early risk stratification in the emergency department (ED) remains challenging. We evaluated the prognostic value of lactate dynamics alongside readily available metabolic markers.

This single-center, retrospective observational study included adults (≥18 years) presenting to the ED with methanol intoxication between 01/2020–03/2023. Demographics, clinical findings, and laboratory values were extracted from electronic records. Lactate was measured at 0, 2, and 4 hours; lactate clearance was calculated as (Initial lactate−Follow-up lactate)/Initial lactate × 100. Outcomes were in-hospital mortality, intensive care unit (ICU) admission, and discharge. Group comparisons and ROC analyses were performed (α = 0.05).

Eighty-two patients were included (mean age 52.9 ± 14.2 years; 92.7% male). In-hospital mortality was 11.0% and ICU admission 54.9%. Non-survivors had higher lactate at presentation (9.04±6.09 vs 4.21 ± 3.83 mmol/L, p < 0.001) and markedly lower/negative lactate clearance (−33.4±95.3% vs 43.1 ± 29.9%, p < 0.001). Lactate predicted mortality with AUC 0.785 (cut-off > 8.5 mmol/L; sensitivity 77.8%, specificity 72.6%). Delta lactate was associated with mortality on univariate analysis but did not yield a clinically useful cut-off. For level of care outcomes, anion gap predicted ICU admission (AUC 0.722), while anion gap ≤18.4 mmol/L predicted discharge (AUC 0.793; sensitivity 85.1%, specificity 73.3%). Base excess contributed to prediction of ICU admission and discharge.

In methanol intoxication, both admission lactate and early lactate clearance are strong prognostic indicators of mortality. Anion gap and base excess add complementary value for predicting ICU need and discharge. Incorporating these routinely available parameters into ED assessment may improve early risk stratification and guide timely management decisions.