Scope of testing
One reason why postmortem toxicology is so challenging is that, in theory, it can require a search for any drug or poison of toxicological significance. However, this approach, while idealistic, is not practicable for any laboratory that receives many hundreds or thousands of cases each year. A more practical approach includes a search for the common drugs of abuse, prescription and non-prescription drugs, followed, as necessary, by specific analyses as indicated by the case history. Any laboratory that claims to perform general ‘drug screening’ should, at a minimum, have protocols that include gas chromatography (GC) and mass spectrometry (MS) or, as is becoming more common, liquid chromatography–mass spectrometry (LC-MS) and that are not limited to a panel of immunoassay assay screens (e.g. for drugs of abuse). Other substances may be included, depending on the case history. Carbon monoxide should be tested for in garage-related deaths, or circumstances in which malfunctioning fossil-fuel devices are a possibility (e.g. house furnace/boiler, propane-powered devices). Deaths caused by cyanide are often occupation ally related (e.g. metal plating, geology, agriculture). In practice, the laboratory investigation is directed by information received from the submitter of the specimens, including basic details of the circumstances of death and the key autopsy findings. No matter how good the laboratory is, some relatively common prescription and non-prescription drugs are not detected readily by commonly used methods. Also, in some geographical regions, particularly those devoted to large-scale agriculture and with relatively limited access to drugs, deaths caused by pesticides and rodenticides may be common, which necessitates a modified approach to drug screening .The scope of laboratory testing may vary considerably with case history and is often progressive. Initial negative findings after preliminary testing may prompt further discussions with investigators or pathologists. The death may involve drugs or other poisons that are not detected readily by the screening methods used by the laboratory.
