Clinical and forensic examinations of glycaemic marker methylglyoxal by means of high performance liquid chromatography–tandem mass spectrometry

The postmortem determination of hyperglycaemic coma is quite difficult because of the lack of morphological findings and the difficult interpretation of biochemical parameters. Methylglyoxal (MG) is a reactive oxoaldehyde, which is mainly derived from glycolysis. An electrospray ionisation liquid chromatography–tandem mass spectrometric procedure for the determination of methylglyoxal in human serum and postmortem blood was developed. It involves protein precipitation with perchloric acid and a derivatisation step with 2,3-diaminonaphthalene. The assay was validated according to international guidelines. Serum samples from diabetics obtained at a diabetes clinic and from non-diabetics were used to assess data about reference concentrations in human serum. The assay showed linearity within the physiological concentrations in serum (5–500 ng/ml). Intraday imprecision at three concentrations was 10.3, 9.2 and 8.3 %, and interday imprecision was 15.3, 14.2 and 9.4 %; the limit of detection was 1.3 ng/ml, and limit of quantification, 3.2 ng/ml. One hundred and eighteen clinical (100 diabetics, 18 non-diabetics) and 98 forensic samples (84 non-diabetics, 14 in a status of hyperglycaemic coma) were measured. During life, diabetics showed significantly ( p < 0.001) higher serum concentrations of MG than non-diabetics. After death, concentrations of MG increased significantly ( p < 0.001). However, there was no correlation between the sum formula of Traub in vitreous humour and MG femoral blood concentrations ( R = 0.237). This indicates that MG concentrations in the deceased cannot distinguish deaths due to a hyperglycaemic coma from other causes of death.