Case Presentation: A 51-year-old man with a past medical history of diabetes mellitus, polysubstance abuse, chronic kidney disease stage 3a and major depressive disorder presented to a Texas hospital after a suicide attempt using liquid mercury. While intoxicated from cocaine days prior, he broke into old abandoned homes and obtained liquid mercury from their thermostats which he injected into his left hand using his insulin syringe. Poison control was contacted to ensure containment and community cleanup. Physical exam including vitals were all within normal limits. Laboratory studies were only remarkable for a mild creatinine elevation of 1.9 from a baseline of 1.2. Serum and urine mercury levels were ordered. ECG was normal. Xrays of his left arm and chest were consistent with mercury poisoning demonstrating small high-density opacities in his left forearm as well as innumerable diffusely distributed opacities in his lungs. His creatinine returned to baseline with fluids. He exhibited no signs of neurological, gastrointestinal, pulmonary or renal deficit from mercury poisoning. Mercury serum level was elevated to 55 mcg/L however with lack of symptoms, he was not given chelation therapy and was instead monitored closely. Subsequently, he was transferred to psychiatry for management of his suicidal ideations.
Discussion: Previously a common constituent of many medications, mercury now can be found in blood pressure cuffs, thermometers, thermostats, manufacturing, mining, fungicides and vaccines. The three most common exposures are fish consumption, dental amalgams and occupational exposure. Mercury naturally exists in three forms: organic, inorganic and elemental/metallic which is most common. Mercury poisoning symptoms include fatigue, anxiety, depression, headache, insomnia, weight loss, fevers, memory loss, gingivitis, salivation, metallic taste in mouth, gastroenteritis, paresthesia, ataxia, tremors, erethism, acrodynia, proteinuria as well as pneumonitis, erosive bronchitis, bronchiolitis and renal failure. Blood mercury levels do not correlate with symptoms, however normal limits for blood mercury some have been proposed at 7.1 mcg/L with neurological findings found at 200 mcg/L. Mean half-life in blood is about 40-50 days. Chelating agents such as dimercaprol (BAL), 2,3-dimercaptosuccinic acid (DMSA) and penicillamine are usually reserved for symptomatic patients. Any subcutaneous deposits may need surgical removal. GI decontamination may be considered if ingestion was acute.
Conclusions: Although mercury poisoning is now rarely seen in the United States, the differential diagnosis for many common subjective complaints including fatigue, insomnia, weight loss should include mercury toxicity. The ability to identify the presenting symptoms will allow hospitalists to diagnose and manage this rare although serious exposure.