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Abstract: PO1485

Lactate Gap as Initial Indicator for Ethylene Glycol Toxicity

Session Information

Category: Trainee Case Report

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Madireddy, Varun, Zucker School of Medicine at Hofstra/Northwell, Great Neck, NY, Hempstead, New York, United States
  • Finger, Mark A., Zucker School of Medicine at Hofstra/Northwell, Great Neck, NY, Hempstead, New York, United States
Introduction

Ethylene glycol poisoning is a medical emergency which on initial presentation can be missed if the clinician does not have a high index of suspicion. Treatment of ethylene glycol toxicity is time dependent in preventing morbidity and mortality, thus early recognition and intervention is of critical value. In this case report we aim to focus on the lactate gap as the first indicator of ingestion.

Case Description

50-year-old female was brought in by EMS after being found unresponsive and covered in vomitus. Vital signs were stable. The patient was thought to have had a seizure causing the lactic acidosis and was post ictal. Labs are shown below.
Ethylene glycol toxicity was made the presumptive diagnosis. The patient was transferred to the medical ICU and given a loading dose of fomepizole while hemodialysis was being arranged. The patient then had one session of hemodialysis in the medical ICU and repeat blood gas is displayed below.

Discussion

The diagnosis of ethylene glycol poisoning remains challenging due to non-specific signs and symptoms on presentation. Presentation and lab values may differ depending on the time and amount since ingestion. Access to real-time ethylene glycol serum concentration is uncommon in many health facilities, so the diagnosis relies upon a high index of suspicion. Laboratory studies, specifically the “lactate gap”, can be used in aiding the diagnosis.
The “lactate gap” is a lab artefact due to a chemical cross reaction. Most POC whole blood analyzers use the enzyme lactate oxidase which cross reacts with the breakdown products of ethylene glycol, specifically glycolate. The lab instrument cannot differentiate between lactate and glycolate because of their structural similarity. Laboratory serum analyzers which are used for routine venous blood samples have less cross-reactivity and thus show a minimal elevation of lactate in comparison. In addition to securing the diagnosis, the lactate gap can be used to monitor clearance of the glycol metabolites.

Laboratory Values
MeasurementOn arrival2 hours laterPost HemodialysisRef Values
pH7.337.227.437.35-7.45
pCO225404035-45 mmHg
Bicarbonate1292323-30 mEq/L
Lactate (POCT)27232.40.5-2.2 mmol/L
Lactate, bloodN/A8.12.10.5-2 mmol/L
"Lactate gap"N/A14.90.3 
Osmolar gap99N/A9<10 mOsms