Endogenous GHB in Segmented Hair Part I: Inter-individual Variation for Group Comparisons.

While earlier studies have attempted to resolve the challenges encountered when interpreting gamma-hydroxybutyric acid (GHB) concentrations in hair (primarily due to its endogenous presence), few have had large sample sizes. The first objective of this study was to evaluate the inter-individual variation of endogenous GHB concentrations. The second objective, to be detailed in another report, was to assess intra-individual variation and the impact on exogenous GHB discrimination.