Endogenous γ-hydroxybutyric acid levels in postmortem blood

Abstract

The goal of this study was to determine how the postmortem interval and duration of storage of blood at 4 °C affect endogenous γ-hydroxybutyric acid (GHB) levels in blood. Forty-three autopsy cases of non-users of GHB were involved. The postmortem interval ranged from 8 to 132 h. Blood samples were collected and stored without any preservatives at 4 °C for 1 day up to 15 months until analysis. In some cases, samples were also stored at −20 °C for 10 days to 7 months to determine GHB levels at autopsy. Blood GHB concentrations were measured by headspace gas chromatography after GHB was converted to γ-butyrolactone. Blood GHB concentrations ranged from 0 to 43.0 μg/ml and averaged 9.80 μg/ml. A positive correlation was observed between concentration and postmortem interval ( r=0.571), but no correlation was found between concentration and storage interval at 4 °C. In 14 blood samples stored at −20 and 4 °C for 10 days, GHB concentrations were 4.55±3.88 and 6.06±4.27 μg/ml, respectively. In another eight blood samples stored at −20 and 4 °C for 1–7 months, GHB concentrations were 3.77±2.76 and 5.49±2.97 μg/ml, respectively. A large portion of endogenous GHB detected in blood of corpses may be produced during the interval between death and autopsy, rather than during storage of blood at 4 °C until analysis. In an additional experiment, it was suggested that glycolysis by bacteria may enhance endogenous GHB production.