γ-hydroxybutyrate serum levels and clinical syndrome after severe overdose

Study objective: We discuss a prospective case series of patients who present with a severe γ-hydroxybutyrate intoxication with confirmatory serum and urine γ-hydroxybutyrate levels. Methods: Patients with a clinical suspicion of γ-hydroxybutyrate-like drug overdoses and a Glasgow Coma Scale score of 8 or lower were identified from July 1998 through January 1999. Serial serum specimens and a single urine specimen were collected. The levels of γ-hydroxybutyrate were performed by gas chromatography-mass spectrometry. Results: All 16 suspected severe γ-hydroxybutyrate overdose patients had significant serum or urine levels of γ-hydroxybutyrate. Serum levels ranged from 45 to 295 mg/L, with a median of 180 mg/L (interquartile range [IQR] 235 to 118 mg/L). Patients who developed a Glasgow Coma Scale score of 3 had serum levels that ranged from 72 to 300 mg/L, with a median of 193 mg/L (IQR 242 to 124 mg/L). The time of awakening ranged from 30 minutes to 190 minutes, with a median of 120 minutes (IQR 150 to 83 minutes). Quantitative serum γ-hydroxybutyrate levels did not correlate with the degree of coma or the time to awakening. Urine levels ranged from 432 to 2,407 mg/L, with a median of 1,263 mg/L (IQR 1,550 to 796 mg/L). Mild transitory hypoventilation occurred in 5 of the 16 patients. Conclusion: All of our patients with clinically suspected severe γ-hydroxybutyrate overdose were confirmed to have significant serum and urine levels of exogenous γ-hydroxybutyrate. They presented with severe coma that lasted 1 to 2 hours. Transient hypoventilation occurred in one third of these patients. [Ann Emerg Med. 2003;42:3-8.]