WBR0957

Author	[[PageAuthor::Mugilan Poongkunran M.B.B.S [1]]]
Exam Type	ExamType::USMLE Step 3
Main Category	MainCategory::Emergency Room
Sub Category	SubCategory::Hematology
Prompt	[[Prompt::A 54 year old woman comes to the emergency department with complaints of shortness of breath. She was in her usual state this morning but suddenly developed these symptoms. Her past history is otherwise insignificant and her family history is unremarkable. She is a chronic smoker and smoked two packs of cigarette for the past 25 years. She attained menopause at the age of 50 and is taking estrogen supplements. Her vitals are temperature: 36.7 C, blood pressure: 130/80 mmHg, pulse: 90/min and respiration: 15/min. The patients pulse oximetry shows 92 % on 4-litres of oxygen. All system examinations are normal. V/Q scan of the chest shows high probablity for pulmonary embolism. Her initial laboratory values are : Hb : 11 g/dl Hct : 37% RBC’s : 3 million/cmm WBC’s : 8000/cmm Platelet’s : 300,000/cmm PT : 13 sec (N 11-15 sec) INR : 1.06 You start the patient on unfractionated heparin and warfarin. Her symptoms gradually resolve over the next three days. A repeat CBC on the 5th day reveals a platelet count of 60,000/cumm. Which of the following is the most appropriate step in the management of this patient?]]
Answer A	AnswerA::Stop unfractionated heparin, warfarin and start low molecular weight heparin
Answer A Explanation	AnswerAExp::''' Incorrect ''' : LMW heparin should not be substituted for unfractionated heparin after HIT develops.
Answer B	AnswerB::Stop unfractionated heparin and continue warfarin
Answer B Explanation	[[AnswerBExp:: Incorrect  : Warfarin should not be given to patients who have HIT until the thrombocytopenia resolves following the use of agents such as argatroban or hirudin.]]
Answer C	AnswerC::Stop unfractionated heparin, warfarin and start bivaluridin
Answer C Explanation	[[AnswerCExp:: Correct  : Patients who develop HIT will have an ongoing need for anticoagulation due to the HIT itself, and possibly due to the condition for which heparin was administered originally. Bivalirudin (Angiomax), a hemodialyzable direct thrombin inhibitor and Argatroban, a direct thrombin inhibitor should be initiated.]]
Answer D	AnswerD::Stop unfractionated heparin, warfarin and start I.V corticosteroids
Answer D Explanation	[[AnswerDExp:: Incorrect  : There is no role for steroids in HIT. They are used in the treatment of immune thrombocytopenic purpura (ITP).]]
Answer E	AnswerE::Continue unfractionated heparin and warfarin
Answer E Explanation	[[AnswerEExp:: Incorrect  : Type I heparin-induced thrombocytopenia that is typically characterized by a slight fall in platelet count (< 50%) within the first two days after heparin initiation and often returns to normal with continued heparin administration. This patient has type II HIT and hence warfarin and all heparin products need to be discontinued.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::Heparin-induced thrombocytopenia is diagnosed when the platelet count falls by > 50% typically after 5-10 days of heparin therapy. The first intervention in a patient with suspected HIT should be immediate cessation of all exposure to heparin and replacement with a suitable alternative anticoagulant as they are still at the risk of thrombosis. Low molecular weight heparin is deemed contraindicated in HIT. Lepirudin, fondaparinux, bivalirudin, argatroban, danaparoid or other direct thrombin inhibitors are used to treat the thrombotic state. Out of these lepirudin and argatroban are available for use in USA. Educational Objective: References: ]]
Approved	Approved::Yes
Keyword	WBRKeyword::Heparin induced thrombocytopenia, WBRKeyword::HIT
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