Ethylene Glycol, Serum
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Ethylene glycol, present in antifreeze products, may be ingested accidentally or for the purpose of inebriation or suicide. Ethylene glycol itself is relatively nontoxic, and its initial central nervous system (CNS) effects resemble those of ethanol. However, metabolism of ethylene glycol by alcohol dehydrogenase results in the formation of a number of acid metabolites, including oxalic acid and glycolic acid. These acid metabolites are responsible for much of the toxicity of ethylene glycol.
Three stages of ethylene glycol overdose occur. Within the first few hours after ingestion, there is transient excitation followed by CNS depression. After a delay of 4 to 12 hours, severe metabolic acidosis develops from accumulation of acid metabolites. Finally, delayed renal insufficiency follows deposition of oxalate in renal tubules.
Ethylene glycol toxicity is treated with 4-methylpyrazole (4-MP; fomepizole) or ethanol to saturate the enzyme alcohol dehydrogenase and prevent conversion of ethylene glycol to its toxic metabolites.
Confirming and monitoring ethylene glycol toxicity
Toxic concentrations greater than or equal to 20 mg/dL may cause intoxication, CNS depression, metabolic acidosis, renal damage and hypocalcemia. Ingestion of ethylene glycol can be fatal if patients do not receive immediate medical treatment.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Propionic acid produced in the rare inborn error of metabolism methylmalonic acidemia may be confused with ethylene glycol in the gas chromatographic assay.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Toxic concentration: > or =20 mg/dL
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Porter W: Clinical toxicology. In Tietz Textbook of Clinical Chemistry. Edited by CA Burtis, DE Bruns. Vol 4. St. Louis, MO. Elsevier Saunders, 2006, pp 1287-1369
2. O'Brien CP: Drug addiction and drug abuse. In Goodman and Gilman's The Pharmacological Basis of Therapeutics. Edited by LL Brunton, JS Lazo, KL Parker. Vol 11. McGraw-Hill Book Company, Inc, 2006. Available at http://www.accessmedicine.com/content.aspx?aID=941547
3. Anderson IB: Ethylene glycol and other glycols. In Poisoning and Drug Overdose. Edited by KR Olson. Fifth edition. Available at http://www.accessmedicine.com/content.aspx?aID=2683943