The Case for Laboratory Developed Procedures: Quality and Positive Impact on Patient Care

Kaul, Karen L.; Sabatini, Linda M.; Tsongalis, Gregory J.; Caliendo, Angela M.; Olsen, Randall J.; Ashwood, Edward R.; Bale, Sherri; Benirschke, Robert; Carlow, Dean; Funke, Birgit H.; Grody, Wayne W.; Hayden, Randall T.; Hegde, Madhuri; Lyon, Elaine; Murata, Kazunori; Pessin, Melissa; Press, Richard D.; Thomson, Richard B.

Ethylene glycol is a colorless, sweet-tasting liquid commonly encountered in automobile antifreeze. Because of this widespread availability, it is also a commonly encountered toxicological agent in both accidental and self-inflicted poisonings with 6078 exposures in 2014. 160 Ethylene glycol poisoning classically presents with a metabolic acidosis caused by the production of toxic metabolites, primarily glycolic acid and oxalic acid. This is also often accompanied by an anion gap and osmolal gap. Untreated ethylene glycol poisoning can also progress to acute renal failure when high levels of oxalate anions combine with calcium to develop crystals in the kidneys and urinary tract. 161 Ethylene glycol poisoning is an urgent, toxicological emergency. Once ethylene glycol is identified, the drug fomepizole is typically administered. Fomepizole inhibits alcohol dehydrogenase, the enzyme that metabolizes ethylene glycol, to slow the accumulation of toxic metabolites. Fomepizole and ethanol dramatically lengthen the half-life of ethylene glycol, and therefore, hemodialysis is often required to clear the poison. 162 Both the diagnosis and treatment of ethylene glycol poisoning are heavily dependent on laboratory measurements. No FDA-approved assays for ethylene glycol are currently available, and all testing is performed by laboratory-developed procedures. The 3 most common methods for the analysis of ethylene glycol are GC with flame ionization detector, GC with MS, and enzymatic assays. 163, 164 Gas chromatography with mass spectrometry is considered the gold standard for the analysis of ethylene glycol, as it can differentiate it from interferences that plague the other 2 methods. 163, 165 In addition to initial detection needed for diagnosis, the ethylene glycol blood concentration is used to determine when hemodialysis has cleared ethylene glycol to undetectable levels.