View source for WBR0967

 {{WBRQuestion
|QuestionAuthor= {{M.P}}
|ExamType=USMLE Step 3
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|SubCategory=Hematology
|MainCategory=Emergency Room
|MainCategory=Emergency Room
|SubCategory=Hematology
|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 respirations: 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 probability 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 would have been the most useful step that would have prevented the condition?

|Explanation=Heparin-induced thrombocytopenia is diagnosed when the platelet count falls by > 50% typically after 5-10 days of heparin therapy.  Low molecular weight (LMW) heparin, the heparin analogue [[fondaparinux]], and [[heparinoids]], such as [[danaparoid]], are associated with a much lower incidence of HIT than unfractionated heparin.  Limiting heparin duration to less than five days and starting warfarin early to minimize the length of heparin use in patients requiring long-term anticoagulation are two often overlooked strategies.
|AnswerA=Initial regimen on low molecular weight heparin 


|AnswerAExp=''' Correct ''' : [[Low molecular weight heparin]] (LMWH), the heparin analogue fondaparinux, and heparinoids, such as danaparoid, are associated with a much lower incidence of HIT than [[unfractionated heparin]].
|AnswerB=Monitoring prothrombin time and platelet count

|AnswerBExp=''' Incorrect ''' : [[PT]] and platelet count are used to monitor [[warfarin]] response and heparin complications.  They do not affect the development of HIT.
|AnswerC=Initial regimen with bivaluridin

|AnswerCExp=''' Incorrect ''' : [[Lepirudin]], [[fondaparinux]], [[bivalirudin]], [[argatroban]], danaparoid or other direct thrombin inhibitors are used to treat the thrombotic state after the patient develops HIT.
|AnswerD=Adding  I.V corticosteroids to heparin and warfarin

|AnswerDExp=''' Incorrect ''' : There is no role for steroids in the prevention of HIT.  They are used in the treatment of [[ITP]].
|AnswerE=Higher doses of unfractionated heparin and warfarin
|AnswerEExp=''' Incorrect ''' : 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.  Increased doses of heparin and warfarin are given to sub-therapeutic anti-coagulation. 
|RightAnswer=A
|WBRKeyword=HIT
|Approved=Yes
}}