WBR0067
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1] (Reviewed by Will Gibson)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry, MainCategory::Pathology, MainCategory::Pharmacology |
| Sub Category | SubCategory::General Principles |
| Prompt | [[Prompt::A 49-year-old male factory worker presents to the emergency room with complaints of weakness, abdominal cramps, vomiting and passage of loose "rice-water" stools. Physical examination reveals an abnormal cardiac rhythm, peripheral motor and sensory neuropathy. Skin examination reveal hyperkeratosis of the palms and feet. The physician notes the patient's breath has a strong “garlic” odor. Which of the following is most likely 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 occurs 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. Mercury 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::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. Poisoning occurs either through ingestion or inhalation. Typical symptoms include gastrointestinal disturbances (nausea and vomiting, abdominal pain, “rice water stools”), and sensory neuropathy/weakness. Because arsenic is a metabolic poison, highly metabolic tissues such as the CNS are impacted. In particular, patients may manifest signs suggestive of peripheral neuropathy. This neural pathology is thought to arise from segmental demyelination, and axonal degeneration. One late complication of chronic arsenic exposure is angiosarcoma.
Arsenic's toxic metabolite arsenite binds to the sulfhydryl (thiol) groups found in nearly all proteins with high affinity , thereby inhibiting their activity. While its mechanism of toxicity is highly pleiotropic, arsenic is considered a glycolytic poison that causes glycolysis to produce zero net ATP. Acute ingestion damages capillaries and small vessels, increasing permeability, leading to hypoxia, transudation of fluid, inflammation, necrosis, and hypovolemia. Treatment should involve gastric lavage, IV hydration, and pharmacologic chelation with either dimercaprol or succimer. Note: Penicillamine is no longer recommended for arsenic poisoning; First Aid 2014 (page 252) is incorrect. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Poison, WBRKeyword::Arsenic poisoning, WBRKeyword::Toxin, WBRKeyword::Toxins, WBRKeyword::Arsenic, WBRKeyword::Biochemistry |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |