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.