Postmortem biochemistry: Current applications

Abstract

The results of biochemical analyses in specimens obtained postmortem may aid death investigation when diabetic and alcoholic ketoacidosis is suspected, when death may have been the result of drowning, anaphylaxis, or involved a prolonged stress response such as hypothermia, and in the diagnosis of disease processes such as inflammation, early myocardial infarction, or sepsis. There is often cross-over with different disciplines, in particular with clinical and forensic toxicology, since some endogenous substances such as sodium chloride, potassium chloride, and insulin can be used as poisons. The interpretation of results is often complicated because of the likelihood of postmortem change in analyte concentration or activity, and proper interpretation must take into account all the available evidence. The unpredictability of postmortem changes means that use of biochemical measurements in time of death estimation has little value. The use of vitreous humour is beneficial for many analytes as the eye is in a physically protected environment, this medium may be less affected by autolysis or microbial metabolism than blood, and the assays can be performed with due precaution using standard clinical chemistry analysers. However, interpretation of results may not be straightforward because (i) defined reference ranges in life are often lacking, (ii) there is a dearth of knowledge regarding, for example, the speed of equilibration of many analytes between blood, vitreous humour, and other fluids that may be sampled, and (iii) the effects of post-mortem change are difficult to quantify because of the lack of control data. A major limitation is that postmortem vitreous glucose measurements are of no help in diagnosing antemortem hypoglycaemia.

Postmortem Biochemistry and Toxicology

“…Clinical interpretation of postmortem biochemistry and toxicology results is a complex area [22,26,27]. It used to be assumed that concentrations of drugs and some other poisons measured in blood obtained at autopsy reflected the situation at the time of death, hence interpretation of results could be made simply by comparison with 'normal' or 'therapeutic' plasma concentration data.…”

“…Sampling for postmortem biochemistry and toxicology is not always straightforward, yet is of vital importance if all subsequent analytical work is not to be invalidated [22][23] (Table-1 • Name of the individual collecting the specimen…”

“…Some laboratories provide specimen containers for collecting postmortem blood, urine, and other specimens. Vitreous humor is preferred for much postmortem biochemistry because it lies in a relatively protected part of the body and is less susceptible to postmortem change than fluids such as blood [22].…”

Valores de magnésio no humor vítreo de bovinos abatidos para consumo no sul do Estado Do Rio De Janeiro

“…Atualmente as possibilidades investigativas são inúmeras e incluem DNA (Belsey & Flanagan, 2016), anticorpos (Tormey, 2016), choque anafilático (Han et al, 2015), glicemia (Boulagnon et al, 2011), gestação (Han et al, 2015), álcool e drogas (Metushi et al, 2016). Em veterinária, a análise do vítreo é pouco empregada, havendo relatos de sua aplicação diagnóstica na hipomagnesemia (McDowell 1992;Ramírez et al, 1998;Mattioli et al, 2000;McCoy et al, 2001), alterações renais (Choo-Kang et al, 1983) e intoxicações (Lincoln & Lane, 1985).…”

Targeted autopsy practice for coroners is likely to miss diagnoses

“…Alcohols, drugs of abuse, salicylate, paracetamol and glucose were the only analytes reported 2. A recent review detailed the current potential of appropriate postmortem biochemical analysis of vitreous and other samples which could improve the quality of cause of death certification 3. Unsuspected cases of dehydration, renal failure, alcoholic ketoacidosis and diabetes are likely missed currently, particularly in the elderly.…”