Poisoning by metals

Lead can be absorbed after inhalation or ingestion and is toxic to most organ systems. Management involves avoidance of exposure and, in more severe cases, chelation therapy with either sodium calcium edetate or dimercaptosuccinic acid. Iron poisoning causes metabolic effects in proportion to the concentrations of free iron, although individual responses vary. Toxicity is therefore related to the dose ingested. Iron concentrations can rise and fall, making plasma concentrations difficult to interpret in acute poisoning. Clinical features include severe gastrointestinal irritation, cardiovascular collapse and direct organ damage to the liver and kidneys. Unconsciousness occurs in severe cases. The chelating agent desferrioxamine is used as the antidote, although uncertainty remains over the optimal dose in individual patients. Chelating agents are also used in other metal poisonings. It is advised that the investigation and management of suspected heavy metal poisoning should be conducted in consultation with a poison centre and/or a clinical toxicologist.