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|SubCategory=Hematology
|SubCategory=Hematology
|Prompt=A 23 year old woman is brought to the emergency department after consuming rat poison in a suicide attempt. On arrival, EMS report several episode of hematemesis on the way to the hospital. The patient is found to be hypotensive and tachycardic with altered mental status. Which of the following mechanisms are responsible for this patient's presentation?
|Prompt=A 23 year old woman is brought to the emergency department after consuming rat poison in a suicide attempt. On arrival, EMS report several episode of hematemesis on the way to the hospital. The patient is found to be hypotensive and tachycardic with altered mental status. Which of the following mechanisms are responsible for this patient's presentation?
|Explanation=Rodenticides, or rat poisons are a variety of agent used to exterminate rodents. The most commonly used rodenticides are anticoagulants typically of the coumarin class notably warfarin, coumatetralyl, difenacoum, and brodifacoum. These agents act as they would for therapeutic purposes by inhibiting the gamma-carboxylation of coagulation factors that requires vitamin K. Coumarins inhibit the enzyme epoxide reductase that forms the active vitamin K needed for carboxylation. Blood levels of factors II, VII, IX and X drop to dangerously low levels after ingestion of large doses of rat poison usually leading to massive GI bleeding that may manifest as hematemesis. Treatment for early ingestion includes syrup of ipecac and gastric lavage. For late cases presenting with massive bleeding, treatment is typically with fresh frozen plasma and vitamin K administration.
Reference: The most common types of rat poison are anticoagulants form the coumarin family that inhibit epoxide reductase and lead to a decrease in clotting factors.
|AnswerA=Inhibition of epoxide reductase
|AnswerA=Inhibition of epoxide reductase
|AnswerAExp=Rodenticides are usually derivatives of coumarin and inhibit epoxide reductase leading to a decrease in clotting factors.
|AnswerB=Activation of plasminogen
|AnswerB=Activation of plasminogen
|AnswerBExp=Fibrinolytics typically cause activation of plasminogen. Rat poison works by a different mechanism.
|AnswerC=Activation of antithrombin III
|AnswerC=Activation of antithrombin III
|AnswerCExp=Heparin causes activation of antithrombin III. Rat poison works by a different mechanism.
|AnswerD=Inhibition of GpIIbIIIa expression
|AnswerD=Inhibition of GpIIbIIIa expression
|AnswerDExp=ADP receptor blockers such as clopidogrel cause inhibition of GpIIbIIIa expression. Rat poison works by a different mechanism.
|AnswerE=Inhibition of thromboxane A2 production
|AnswerE=Inhibition of thromboxane A2 production
|AnswerEExp=Aspirin inhibits thromboxane A2 production leading to a decrease in platelet aggregation.
|RightAnswer=A
|RightAnswer=A
|WBRKeyword=Rat poison, Vitamin K, Fresh frozen plasma, epoxide reductase
|WBRKeyword=Rat poison, Vitamin K, Fresh frozen plasma, epoxide reductase
|Approved=No
|Approved=No
}}
}}

Revision as of 08:00, 21 November 2013

 
Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pathophysiology, MainCategory::Pharmacology
Sub Category SubCategory::Hematology
Prompt [[Prompt::A 23 year old woman is brought to the emergency department after consuming rat poison in a suicide attempt. On arrival, EMS report several episode of hematemesis on the way to the hospital. The patient is found to be hypotensive and tachycardic with altered mental status. Which of the following mechanisms are responsible for this patient's presentation?]]
Answer A AnswerA::Inhibition of epoxide reductase
Answer A Explanation AnswerAExp::Rodenticides are usually derivatives of coumarin and inhibit epoxide reductase leading to a decrease in clotting factors.
Answer B AnswerB::Activation of plasminogen
Answer B Explanation AnswerBExp::Fibrinolytics typically cause activation of plasminogen. Rat poison works by a different mechanism.
Answer C AnswerC::Activation of antithrombin III
Answer C Explanation AnswerCExp::Heparin causes activation of antithrombin III. Rat poison works by a different mechanism.
Answer D AnswerD::Inhibition of GpIIbIIIa expression
Answer D Explanation AnswerDExp::ADP receptor blockers such as clopidogrel cause inhibition of GpIIbIIIa expression. Rat poison works by a different mechanism.
Answer E AnswerE::Inhibition of thromboxane A2 production
Answer E Explanation AnswerEExp::Aspirin inhibits thromboxane A2 production leading to a decrease in platelet aggregation.
Right Answer RightAnswer::A
Explanation [[Explanation::Rodenticides, or rat poisons are a variety of agent used to exterminate rodents. The most commonly used rodenticides are anticoagulants typically of the coumarin class notably warfarin, coumatetralyl, difenacoum, and brodifacoum. These agents act as they would for therapeutic purposes by inhibiting the gamma-carboxylation of coagulation factors that requires vitamin K. Coumarins inhibit the enzyme epoxide reductase that forms the active vitamin K needed for carboxylation. Blood levels of factors II, VII, IX and X drop to dangerously low levels after ingestion of large doses of rat poison usually leading to massive GI bleeding that may manifest as hematemesis. Treatment for early ingestion includes syrup of ipecac and gastric lavage. For late cases presenting with massive bleeding, treatment is typically with fresh frozen plasma and vitamin K administration.


Reference: The most common types of rat poison are anticoagulants form the coumarin family that inhibit epoxide reductase and lead to a decrease in clotting factors.
Educational Objective:
References: ]]

Approved Approved::No
Keyword WBRKeyword::Rat poison, WBRKeyword::Vitamin K, WBRKeyword::Fresh frozen plasma, WBRKeyword::epoxide reductase
Linked Question Linked::
Order in Linked Questions LinkedOrder::