ABSTRACT
The diagnostic use of biochemical tests on post-mortem specimens dates back to the earliest development of the technology that enabled us to measure the blood concentrations of various compounds.1 It is safe to assume that almost every analyte measured during life has been investigated in post-mortem samples. Unfortunately, the changes associated with death can profoundly affect the concentration of many intermediary metabolites. As all the dynamic energy systems normally maintaining various concentration gradients begin to fail or run out of substrate, compounds rapidly equilibrate across the various body compartments and cell membranes. Such changes occur in the first few minutes to hours after death. Indeed, many such changes may already be under way before a formal declaration of death by the medical attendants. With time, as cells die, intracellular compounds are released into the surrounding tissue and circulation, compounding the difficulties in the interpretation of results. This is well illustrated by the onset of haemolysis in the circulation. The rupture of red cells and the release of the haemoglobin and all the intracellular enzymes into the bloodstream often signal the end of the useful period for the measurement of many metabolites. Not only does the concentration change in unpredictable ways, but also the ‘matrix’ in which a particular analyte is normally measured may be significantly altered and this can have an important the
fluids decreases, compounds may dissociate from proteins and other ligands thus changing their measured concentration. This is especially important in the interpretation of drug levels. A recent study, which included a large compendium of drugs detected in post-mortem blood, examined the possible factors affecting their concentrations.2 Hormones and other compounds may be similarly affected.
