View source for WBR0960

 {{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 44 year old female comes to the emergency department with an episode of bloody vomiting.  She was in her usual state this morning but suddenly developed these symptoms.  On further review of history, she says she had intermittent passage of black stools over the past 2 weeks.  She is a known hypertensive for past 10 years and on thiazide medications.  Her past history is otherwise insignificant and her family history is unremarkable.  Her menstrual cycles are normal.  She sexually active with her husband and does not use contraceptives.  Her vitals are temperature: 36.7 C, blood pressure: 140/80 mmHg, pulse: 80/min and respiration: 15/min.  Skin is normal and all system examinations are normal.  The patient is treated symptomatically and her laboratory values are as follows : 

Hb : 10 g/dl
RBC’s : 2.5 million/cmm
WBC’s : 6000/cmm
Platelets : 300,000/cmm
Neutrophils : 60 %
Eosinophils : 2 %
Lymphocytes : 32 %
Monocytes : 6 %
MCHC : 34 %
MCV : 85 fl
ESR : 15mm/hr
PT : 13 sec (N 11-15 sec)
APTT : 30 sec (N 25-40 sec)
BT : 18 min (N 2-7 min)
Serum creatinine : 3 mg/dl
Serum calcium : 9 g/dl

Whats is the most likely cause of her symptoms ?

|Explanation=Impaired platelet function is one of the main determinants of bleeding in [[uremia]].  This impairment is multifactorial and includes defects intrinsic to the platelet as well as abnormal platelet-endothelial interaction.  Uremic toxins and anemia also play a role.  Clinical bleeding in uremia may involve the skin resulting in easy bruising, or the oral and nasal mucosa, gingiva, gastrointestinal and urinary tracts, and respiratory system.  Uremic patients may display increased bleeding sensitivity to aspirin, as there is a transient, cyclooxygenase-independent, prolongation of the bleeding time following the use of aspirin in uremic patients that is greater than that seen in normal subjects taking aspirin.   Either [[hemodialysis]] or [[peritoneal dialysis]] can partially correct the bleeding time in approximately two-thirds of uremic patients.  The simplest, most rapidly acting, and probably least toxic acute treatment for platelet dysfunction in the uremic patient is the administration of [[desmopressin]] (dDAVP), an analog of antidiuretic hormone with little vasopressor activity. 
|AnswerA=Immune thrombocytopenia purpura

|AnswerAExp=''' Incorrect ''' : [[Idiopathic thrombocytopenic purpura]] (ITP) is the condition of having a low platelet count ([[thrombocytopenia]]) of no known cause (idiopathic) causing increased bleeding time with normal [[PT]] and [[PTT]].  As most causes appear to be related to antibodies against platelets, it is also known as immune thrombocytopenic purpura.  Although most cases are asymptomatic, very low platelet counts can lead to a bleeding diathesis and purpura.
|AnswerB=Thrombotic thrombocytopenia purpura

|AnswerBExp=''' Incorrect ''' : [[Thrombotic thrombocytopenic purpura]] (TTP or Moschcowitz disease) is a rare disorder of the blood-coagulation system, causing multiple blood clots to form in blood vessels around the body.  Most cases of TTP arise from deficiency or inhibition of the enzyme ADAMTS13, which is responsible for cleaving large multimers of von Willebrand factor, evidencing microangiopathic hemolytic anemia and thrombocytopenia.  This leads to [[hemolysis]] and end-organ damage.  Thus these patients present with increased [[bleeding time]], [[prothrombin time]] and [[partial thromboplastin time]] which is not event in this case. 
|AnswerC=Renal failure


|AnswerCExp=''' Correct ''' : Impaired platelet function is one of the main determinants of bleeding in [[uremia]] causing increased bleeding time with normal other coagulation parameters. 
|AnswerD=Drug-induced thrombocytopenia

|AnswerDExp=''' Incorrect ''' : Drug-induced thrombocytopenia is frequently associated with drug-induced antibodies that cause platelet destruction or clearance by the reticuloendothelial system or may be due to bone marrow suppression by drugs such as chemotherapy agents or [[heparin-induced thrombocytopenia]] (HIT) that is associated with a hypercoagulable state and thrombosis rather than bleeding.
|AnswerE=Von-Willebrand disease
|AnswerEExp=''' Incorrect ''' : [[Von Willebrand disease]] (vWD) is the most common hereditary coagulation abnormality described in humans, although it can also be acquired as a result of other medical conditions.  It arises from a qualitative or quantitative deficiency of von Willebrand factor (vWF), a multimeric protein that is required for platelet adhesion.  It also contributes to fibrin clot formation by acting as a carrier protein for factor VIII, which has a greatly shortened half-life and abnormally low concentration unless it is bound to VWF.  Thus these patients present with increased bleeding time and activated partial thromboplastin time.  The patient's personal and family history of bleeding indicating an autosomal dominant inheritance pattern is not seen in this patient.  
|RightAnswer=C
|WBRKeyword=ITP, HIT, Uremia, Von Willebrand disease
|Approved=Yes
}}