Diagnostic Use
Ethanol level may be useful in assisting clinical management on whether the presenting symptoms can be at least partly explained by alcohol exposure. However, note that there isn’ t always a good correlation between blood alcohol concentration and level of consciousness. Beware of co-existing head injury or hypoglycaemia in causing impaired consciousness. This assay does not measure methanol.
If methanol ingestion is suspected, methanol test should be specifically requested. Under that circumstance, if ethanol is used as an antidote to retard methanol metabolism, a moderate ethanol level should be maintained by serial monitoring on plasma. In selected cases, also consider likelihood of ethylene glycol ingestion.
Rate of metabolism: ethanol is eliminated at a constant rate between 2.4 and 4.8 mmol/L per hour, depending on the individual.
Reference Intervals
Signs and symptoms of intoxication and blood ethanol concentration in non-alcohol dependent population: (significant inter-individual variability between signs/symptoms and blood ethanol levels)
| Signs and symptoms |
Ethanol level |
| Below detectable limit of the ethanol assay: |
< 3 mmol/L |
| Impaired judgement, sensorium, co-ordination. Emotional lability, decreased reflex and increased reaction time. |
> 11 mmol/L |
| Spectrum ranged from confusion, stupor, severe emotional lability, nausea/vomiting, cerebellar/vestibular dysfunction at lower levels to stupor, coma, incontinent and respiratory depression at higher levels. |
> 22 mmol/L |
| Respiratory paralysis, loss of protective reflex, hypothermia, death. It has been reported that the lethal level for 50% of the non-ethanol dependent population is at 98 mmol/L although individuals have survived blood ethanol as high as 326 mmol/L. |
> 88 mmol/L |
This test is NOT accepted for medico-legal purposes. |
The current legal driving limit for adult in NZ is 10.9 mmol/L (50 mg/100mL).
Conversion factor: mg/100 mL = mmol/L x 4.6
Test Method
Principle: Enzymatic
Analyser: Roche Diagnostics Cobas c703/c503
Reagent: ETOH2