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KembaraXtra-Medicine – Mercury Poisoning
Mercury poisoning results from exposure to mercury in one of three primary forms: elemental, inorganic salts, or organic mercury. Mercury exerts its toxic effects by reacting with sulfhydryl groups, leading to enzyme inhibition and disruption of cellular membranes. It also binds to phosphoryl, carboxyl, amide, and amine groups of enzymes, further impairing normal cellular function.
Exposure most commonly occurs through inhalation or ingestion, and less frequently through dermal contact. Occupational and environmental exposures are well recognized and include industries such as chlorine and caustic soda manufacturing, dentistry, photography, taxidermy, mercury mining, and the production of thermometers, batteries, lamps, plastics, paints, pigments, fireworks, and explosives. Contaminated seafood is a major source of organic mercury exposure in the general population.
The clinical presentation varies depending on the form of mercury involved. Elemental mercury exposure most often occurs through inhalation, with symptoms developing within hours. Patients may experience cough and dyspnea that can progress to noncardiogenic pulmonary edema, along with metallic taste, excessive salivation, weakness, nausea, diarrhea, fever, headaches, and visual disturbances. Subcutaneous or intravenous exposure may lead to granulomas, abscesses, or pulmonary embolization. Elemental mercury is relatively nontoxic when ingested orally due to poor gastrointestinal absorption.
Inorganic mercurial salt ingestion causes severe caustic gastrointestinal injury. Symptoms include abdominal pain, nausea, vomiting, diarrhea, sore throat, and a metallic taste. Hemorrhagic gastroenteritis with hematemesis and hematochezia may occur, along with acute tubular necrosis and renal failure. Acrodynia, also known as pink disease, is an idiosyncratic reaction seen mainly in children and is characterized by painful extremities, pink discoloration, and desquamation.
Organic mercury exposure, commonly through contaminated seafood, primarily affects the central nervous system. While mild gastrointestinal symptoms may occur acutely, delayed neurologic toxicity predominates and may take weeks to months to appear. Manifestations include paresthesias, ataxia, paralysis, visual field constriction, dysarthria, hearing loss, progressive cognitive decline, and death. Fetal exposure in utero is associated with particularly severe neurologic outcomes.
Diagnosis relies heavily on a detailed exposure history, including occupational risks and recent seafood consumption. Physical examination focuses on identifying respiratory distress, signs of caustic gastrointestinal injury, and neuropsychiatric abnormalities. Laboratory evaluation may reveal renal dysfunction, but mercury levels in blood or urine can be misleading, especially after recent seafood ingestion. Imaging studies such as chest radiographs may show pulmonary edema or metallic deposits, abdominal radiographs can identify ingested mercury, and head CT may demonstrate cerebellar atrophy in chronic cases.
Management begins with immediate removal from the source of exposure and stabilization of airway, breathing, and circulation. Supportive care includes oxygen, intravenous fluids for hypotension, and treatment of altered mental status with dextrose, thiamine, and naloxone when indicated. Elemental mercury inhalation requires close observation for delayed pulmonary edema. Inorganic mercury ingestion warrants aggressive fluid resuscitation and early treatment of shock or renal failure.
Chelation therapy is indicated for symptomatic patients. Dimercaptosuccinic acid (DMSA) is commonly used for organic and some elemental mercury exposures, while dimercaprol (British anti-Lewisite) is preferred for severe inorganic mercury poisoning. Activated charcoal may be used for recent ingestions. Surgical incision and drainage may be required for subcutaneous mercury deposits.
Hospital admission is recommended for patients with respiratory compromise, renal impairment, caustic gastrointestinal injury, or those requiring chelation therapy. Asymptomatic patients exposed to elemental mercury may be discharged after an adequate observation period. Follow-up includes repeat mercury testing, avoidance of seafood before testing, and referral to medical toxicology. Early recognition, thorough exposure history, and appropriate chelation are critical to reducing morbidity and preventing long-term neurologic sequelae.
Mercury poisoning results from exposure to mercury in one of three primary forms: elemental, inorganic salts, or organic mercury. Mercury exerts its toxic effects by reacting with sulfhydryl groups, leading to enzyme inhibition and disruption of cellular membranes. It also binds to phosphoryl, carboxyl, amide, and amine groups of enzymes, further impairing normal cellular function.
Exposure most commonly occurs through inhalation or ingestion, and less frequently through dermal contact. Occupational and environmental exposures are well recognized and include industries such as chlorine and caustic soda manufacturing, dentistry, photography, taxidermy, mercury mining, and the production of thermometers, batteries, lamps, plastics, paints, pigments, fireworks, and explosives. Contaminated seafood is a major source of organic mercury exposure in the general population.
The clinical presentation varies depending on the form of mercury involved. Elemental mercury exposure most often occurs through inhalation, with symptoms developing within hours. Patients may experience cough and dyspnea that can progress to noncardiogenic pulmonary edema, along with metallic taste, excessive salivation, weakness, nausea, diarrhea, fever, headaches, and visual disturbances. Subcutaneous or intravenous exposure may lead to granulomas, abscesses, or pulmonary embolization. Elemental mercury is relatively nontoxic when ingested orally due to poor gastrointestinal absorption.
Inorganic mercurial salt ingestion causes severe caustic gastrointestinal injury. Symptoms include abdominal pain, nausea, vomiting, diarrhea, sore throat, and a metallic taste. Hemorrhagic gastroenteritis with hematemesis and hematochezia may occur, along with acute tubular necrosis and renal failure. Acrodynia, also known as pink disease, is an idiosyncratic reaction seen mainly in children and is characterized by painful extremities, pink discoloration, and desquamation.
Organic mercury exposure, commonly through contaminated seafood, primarily affects the central nervous system. While mild gastrointestinal symptoms may occur acutely, delayed neurologic toxicity predominates and may take weeks to months to appear. Manifestations include paresthesias, ataxia, paralysis, visual field constriction, dysarthria, hearing loss, progressive cognitive decline, and death. Fetal exposure in utero is associated with particularly severe neurologic outcomes.
Diagnosis relies heavily on a detailed exposure history, including occupational risks and recent seafood consumption. Physical examination focuses on identifying respiratory distress, signs of caustic gastrointestinal injury, and neuropsychiatric abnormalities. Laboratory evaluation may reveal renal dysfunction, but mercury levels in blood or urine can be misleading, especially after recent seafood ingestion. Imaging studies such as chest radiographs may show pulmonary edema or metallic deposits, abdominal radiographs can identify ingested mercury, and head CT may demonstrate cerebellar atrophy in chronic cases.
Management begins with immediate removal from the source of exposure and stabilization of airway, breathing, and circulation. Supportive care includes oxygen, intravenous fluids for hypotension, and treatment of altered mental status with dextrose, thiamine, and naloxone when indicated. Elemental mercury inhalation requires close observation for delayed pulmonary edema. Inorganic mercury ingestion warrants aggressive fluid resuscitation and early treatment of shock or renal failure.
Chelation therapy is indicated for symptomatic patients. Dimercaptosuccinic acid (DMSA) is commonly used for organic and some elemental mercury exposures, while dimercaprol (British anti-Lewisite) is preferred for severe inorganic mercury poisoning. Activated charcoal may be used for recent ingestions. Surgical incision and drainage may be required for subcutaneous mercury deposits.
Hospital admission is recommended for patients with respiratory compromise, renal impairment, caustic gastrointestinal injury, or those requiring chelation therapy. Asymptomatic patients exposed to elemental mercury may be discharged after an adequate observation period. Follow-up includes repeat mercury testing, avoidance of seafood before testing, and referral to medical toxicology. Early recognition, thorough exposure history, and appropriate chelation are critical to reducing morbidity and preventing long-term neurologic sequelae.
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