Unconscious man in his fifties with elevated anion gap

The use of GHB is still widespread with many hospitalised overdose cases.

A man in his fifties was found unconscious in the street and brought to our Acute Admissions. When first examined he was still unconscious, hypothermic, had snoring respiration and smelled of alcohol. He was otherwise haemodynamically stable. Blood samples showed elevated osmolal and anion gaps. The increase in the osmol gap could be explained by the ethanol level of 210 mg/dL (46 mmol/L), but the reason for the increased anion gap was unknown. Flumazenil and naloxone were administered without effect. As the ethanol concentration alone was unlikely to explain the clinical picture, extended toxicological tests were performed. GHB in plasma was very high (5.0 mmol/L; 520 mg/L) even though the sample was taken almost 4 hours after admission. The GHB concentration (present as an anion) corresponded to the increased anion gap. The patient was comatose for approximately 12 hours, which is unusually long in GHB poisoning.

Intoxication with GHB is important to consider in comatose patients where other causes are excluded. Prolonged clinical course may be due to a saturation of the GHB metabolism after a large dose or ingestion of GBL or 1,4-butanediol, both of which are precursors to GHB.