WBR0067

Author	PageAuthor::Ogheneochuko Ajari MB.BS, MS
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Biochemistry, MainCategory::Pathology, MainCategory::Pharmacology
Sub Category	SubCategory::Cardiology, SubCategory::Dermatology, SubCategory::Gastrointestinal, SubCategory::Neurology, SubCategory::Pulmonology, SubCategory::General Principles
Prompt	[[Prompt::A 49 year old factory worker comes to the emergency room with complaints of weakness, abdominal cramps, vomiting and passage of loose stools characteristically described as being like “rice water”. Physical examination reveals an abnormal cardiac rhythm, peripheral motor and sensory neuropathy. Skin examinations reveal hyperkeratosis of the palms and feet with a “garlic” odor. Which of the following is responsible for this patient’s condition?]]
Answer A	AnswerA::Lead
Answer A Explanation	[[AnswerAExp::Lead poisoning usually occurs in children ingesting lead-based paint from old houses. Clinical manifestations are cerebral edema, petechial hemorrhages, lead encephalopathy and peripheral neuropathy with segmental demyelination and/or axonal degeneration. Lead lines are seen in bones on X-ray. In addition, anemia, renal and GI symptoms could be manifested.]]
Answer B	AnswerB::Arsenic
Answer B Explanation	[[AnswerBExp::Arsenic poisoning usually occur among factory workers who work with pesticides, wood preservatives and ceramics. They become poisoned through either ingestion or inhalation. The typical symptoms are nausea and vomiting, abdominal pain, “rice water stools” and garlic breath.]]
Answer C	AnswerC::Mercury
Answer C Explanation	[[AnswerCExp::Sources of mercury include dental amalgam, batteries, wood preservatives and contaminated food. They may be inhaled causing tremors, gingivitis, chest pain, pneumonitis and confusion. Chronic exposure can lead to renal failure, acrodynia and several CNS manifestations.]]
Answer D	AnswerD::Cobalt
Answer D Explanation	AnswerDExp::Cobalt poisoning result from industrial use, medication, radioactive tracer and cancer therapy. Toxicities include nausea, vomiting, paralysis and hypotension.
Answer E	AnswerE::Organophosphate
Answer E Explanation	AnswerEExp::Organophosphates cause time-dependent aging. Toxicities cause Diarrhea, Urination, Miosis, Bradycardia, Bronchoconstriction, CNS and muscle Excitation and Lacrimation, Salivation and Sweating (commonly used mnemonic: DUMBBBELSS)*
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient described in this vignette has Arsenic poisoning, which is common among factory workers who work with pesticides, wood preservatives and ceramics. They become poisoned through either ingestion or inhalation. The typical symptoms are gastrointestinal (nausea and vomiting, abdominal pain, “rice water stools”), sensory neuropathy and weakness. Although there are no morphologic CNS changes, the patients manifest signs suggestive of peripheral neuropathy following segmental demyelination, axonal degeneration, and occasionally onion bulb formation and angiosarcomas (usually from repeated exposures). The typical mechanism in arsenic toxicity is the inhibition of enzymes by binding to sulfhydryl groups, including respiratory enzymes. This poison has a predilection for vascular endothelium, thereby increasing its permeability. In toxic amounts, it can exert multi-systemic effects. Cutaneous: Bowen’s disease, “Mees lines,” hyperkeratosis of palms and soles, and the peculiar “garlic odor”). The typical autopsy findings are multiple keratoses, generalized visceral hyperemia, cerebral edema and many would reveal hepatocellular necrosis and fatty liver, interstitial myocarditis and/or subendocardial hemorrhage, renal tubular degeneration and hemorrhagic arsenical encephalitis. Amounts of 200–300 mg are considered lethal. Educational Objective: References: ]]
Approved	Approved::Yes
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