Laboratory testing in the poisoned patient

Evaluation and medical management of poisoning is often aided by laboratory tests. These range from basic analyses used widely in general clinical care to highly specific and sophisticated toxicology assays. For most poisonings, routine investigations such as measurement of blood glucose and electrolytes provide adequate information needed for management. Specific laboratory tests, such as quantitative assays for paracetamol, ethanol or other toxins, may be necessary. In some cases quantitative serum assays provide the primary information on which clinical management is based.Quantitative testing confirms the concentration of a toxin present and may help predict the anticipated clinical effects and guide management decisions such as the use of antidotes or haemodialysis. Qualitative testing to confirm the presence or absence of a toxin is less frequently helpful in clinical management of poisoning. Drug of abuse (DOA) testing is sometimes included in laboratory evaluation of poisoned patients. Though reported qualitatively as negative or positive, DOA testing is highly complex and easily misinterpreted.This review will discuss laboratory investigations for care of poisoned patients, including available tests and their indications, proper interpretation of results and testing limitations.