New Ethylene Glycol Immunoassay

Effective Thursday October 21, 2010, the University of Iowa Hospitals and Clinics core Clinical Chemistry laboratory will introduce an immunoassay for ethylene glycol, the toxic component of most automobile antifreezes. This new assay will be available in Epic as "Ethylene glycol, plasma" [Epic: LAB7453] and will have a rapid turnaround time compared to the more labor-intensive gas chromatography method. There are two ways this assay will be performed:

1. Following clinician order in Epic

2. Automatic reflex order when the "Ethanol Volatile Panel" [Epic # LAB604] is ordered and the unexplained osmolar gap (including correction for plasma ethanol, if present) is greater than 15.

An ethylene glycol plasma concentration of 10 mg/dL or greater is considered a critical value and will be reported to the ordering clinician.

Currently, the pathology resident on-call is notified when there is a high unexplained osmolar gap. With the introduction of the ethylene glycol immunoassay, the pathology resident will be contacted only if osmolar gap is still greater than 15 after determining the ethylene glycol plasma concentration and estimating the contribution of ethylene glycol to plasma osmolality.

It should kept in mind that the ethylene glycol immunoassay will NOT detect methanol, isopropanol, or propylene glycol, which still require gas chromatography analysis for quantitation. Toxicity by these other alcohols and glycols are not common but do occur and can be clinically serious. Our retrospective analysis from 1996-2010 revealed 10 confirmed methanol and 15 confirmed isopropanol ingestions at the University of Iowa Hospitals and Clinics (i.e., 1 or less per year). If there is a persistent high unexplained osmolar gap and/or clinical suspicion of ingestion of methanol or isopropanol, the gas chromatography analysis can still be ordered after consultation with the pathology resident or attending. Other explanations for high unexplained osmolar gap include heavy ethanol ingestion (with ethanol metabolites and/or ketoacidosis), mannitol, activated charcoal, propylene glycol (often from intravenous medications such as lorazepam or diazepam), or contrast dye.

We hope that the new ethylene glycol immunoassay will facilitate rapid diagnosis of ethylene glycol poisoning, which continues to be a persistent public health issue. The availability of the ethylene glycol immunoassay will also allow for more frequent determinations of follow-up plasma concentrations (if clinically indicated) in patients undergoing therapy with the antidote fomepizole and/or hemodialysis.

Questions should be directed to Matthew Krasowski, MD, PhD, medical director of the Clinical Chemistry