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PTD - 229

Test Directory - Ethylene Glycol


Antifreeze, coolant, brake fluid.

Clinical Indications

Ethylene glycol is very toxic and a fatal dose is approximately 90 mL of pure ethylene glycol (commercial products vary in their concentration of ethylene glycol). Peak concentrations occur 1 to 4 hours after ingestion and it is metabolised to glyoxylic and oxalic acids which are responsible for its toxic effects (acidosis, renal failure, cerebral oedema).

Patients will develop high osmolal gap as they absorb ethylene glycol over the first few hours. Thereafter as the glycol is metabolized to acids the osmolal gap will fall and acidosis worsens. A severely poisoned patient can present early with normal pH; however their osmolal gap will be high. Conversely, absence of an elevated osmolal gap does not exclude serious poisoning since the osmolal gap begins to fall once the elthylene glycol is metabolized in the later stages of poisoning. A elevated anion gap suggests late presentation as a result of development of metabolic acidosis.

Full details of presenting features and patient management are given on Toxbase.

Request Form

Combined Pathology Blood form (Yellow/Black)


Referred test: Analysed by Toxicology Laboratory, Cardiff if specific criteria met. Please note that this assay is not readily available and antidote therapy (either ethanol or fomepizole) must not be withheld whilst waiting for a result. Urgent ethanol levels are available to monitor ethanol treatment, but the laboratory must be contacted.

Specific Criteria

Agreed with Consultant Biochemist in suspected ethylene glycol overdose.

Turnaround Time

3 to 4 days




2 ml


Grey top (Fluoride tube).

Yellow top (SST gel) tubes must not be used as this may cause a false positive result.

Causes for Rejection

Not meeting specific criteria.


An information sheet is available from National Poisons Service (Toxbase)

Lab. Handling

Processing: Aliquot and store at 4C in the separating fridge (CB39). Referral: SASOD & send or BPRO & save.

Version 1.0 / May 2014                                                                                                           Approved by: Consultant Biochemist