Lactate as a diagnostic marker in transient loss of consciousness

Seizure. 2016 Aug;40:71-5. doi: 10.1016/j.seizure.2016.06.014. Epub 2016 Jun 23.


Purpose: The diagnostic classification of disorders of consciousness is often challenging, particularly the distinction between epileptic and non-epileptic seizures. The aim of the study was to examine serum lactate as a diagnostic marker of transient loss of consciousness.

Method: Serum lactate levels in blood samples drawn within 2h of the event were compared retrospectively between patients with generalized tonic-clonic seizures (n=195) and patients with other seizures (syncopes [n=52], psychogenic non-epileptic seizures [n=17], and complex focal seizures [n=37]), respectively.

Results: Serum lactate in patients with generalized tonic-clonic seizures was significantly (p<0.001, Mann-Whitney-U test) increased in comparison to other forms of seizure incidences. The area under the ROC-curve was 0.94 (95% CI 0.91-0.96). For a cut-off concentration of 2.45mmol/l, the sensitivity was 0.88 and the specificity 0.87.

Conclusions: Serum lactate levels in the acute diagnosis were an excellent biomarker for the discrimination of generalized seizures from psychogenic non-epileptic and syncopal events, corroborating its importance for the standard work-up of acute disturbances of consciousness.

Keywords: Diagnostic marker; Lactate; Loss of consciousness; Seizure; Syncope.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers / blood
  • Female
  • Humans
  • Lactic Acid / blood*
  • Male
  • Middle Aged
  • Psychophysiologic Disorders / blood*
  • Retrospective Studies
  • Seizures / blood*
  • Syncope / blood
  • Unconsciousness / blood*


  • Biomarkers
  • Lactic Acid