Quantification of 3-hydroxyglutaric acid in urine, plasma, cerebrospinal fluid and amniotic fluid by stable-isotope dilution negative chemical ionization gas chromatography–mass spectrometry

This paper describes a stable isotope dilution method for quantification of 3-hydroxyglutaric acid (3-HGA) in body fluids. The method comprises a solid-phase extraction procedure, followed by gas chromatographic separation and negative chemical ionization mass spectrometric detection. This method is selective and sensitive, and enables measurement of 3-HGA concentrations in urine-, plasma-, and CSF- samples of controls. The control ranges for 3-HGA were: urine 0.88–4.5 mmol/mol creatinine (n=12); plasma 0.018–0.10 μmol/l (n=10), CSF 0.022–0.067 μmol/l (n=10). We applied this method to measure 3-HGA in body fluids of three patients with glutaric aciduria type I. We also quantified 3-HGA in amniotic fluid of controls (range 0.056–0.11 μmol/l; n=12) and in two samples from fetuses affected with glutaric aciduria type I.