Urinary endogenous concentrations of GHB and its isomers in healthy humans and diabetics

Urinary endogenous concentrations of γ-hydroxybutyric acid (GHB), α-hydroxybutyric acid (AHB) and β-hydroxybutyric acid (BHB) have been investigated for both healthy humans and diabetics by using a newly optimized GC-MS procedure. The endogenous concentrations in healthy volunteers' urine ranged 0.16-2.14 μg/ml for GHB, 0.10-2.68 μg/ml for AHB and 8.51-34.7 μg/ml for BHB. In diabetics, the concentrations ranged 0.17-3.03 μg/ml for GHB, 0.14-124 μg/ml for AHB and 4.94-4520 μg/ml for BHB. Although notably elevated BHB and AHB concentrations were observed for severely uncontrolled diabetics, their GHB concentrations ranged within or near the range seen in healthy humans. The results of this study confirm the previously suggested 10 μg/ml cutoff concentration of urinary GHB to distinguish exogenous GHB, even for uncontrolled diabetic patients suffering severe ketoacidosis.