236 Ch 38 39
Which type of VWD gives a positive response to low-dose ristocetin-induced platelet aggregation?
2B
A patient arrives at the emergency department complaining of pain in the calf of his left leg and shortness of breath. A "stat" D dimer is ordered. Why is this useful information for this patient's care?
An elevated D dimer supports the possibility of deep vein thrombosis.
What procedure is used to quantitate a factor VIII inhibitor?
Bethesda assay
What test is useful for detection of a female carrier of hemophilia A?
Factor VIII to VWF ratio
Which unusual laboratory finding may be present in sepsis-induced DIC?
Fibrinogen may be high because it is an acute phase reactant.
A 67-year-old woman arrives at the emergency department with acute bleeding into the back of the throat. A coagulation screen is ordered with the following results: TestResultReference Range1:1 Mix with Normal PlasmaProthrombin time (PT)12 seconds11-15 seconds Partial thromboplastin time (PTT)57 seconds25-37 seconds36 seconds (immediate)Fibrinogen450 mg/dL150-400 mg/dL What would be a reasonable next step to perform?
Incubate the 1:1 mix at 37° C for 1 hour and then repeat the PTT.
What coagulation screening test is the most sensitive for detecting mild liver disease?
PT
Which of the following tests is increased in a patient with severe hemophilia A?
PTT
What tests should be performed on a regular basis on patients receiving therapeutic heparin?
PTT and platelet count
A thrombosis risk testing profile is ordered on a patient being treated with warfarin for a blood clot in the leg. Select the best course of action.
Recommend the testing be postponed until the warfarin is discontinued.
When the chromogenic assay for antithrombin is performed, which of the following is true?
The colored end-product intensity is inversely proportional to the antithrombin concentration.
What is important about the test systems used for detection of the lupus anticoagulant?
The patient plasma and normal plasma used for mixing studies should be platelet poor.
A 21-year-old woman has a primary complaint of menorrhagia. Her coagulation screen gives the following results. TestTest ResultReference rangeProthrombin time (PT)12.0 seconds11-15 secondsPartial thromboplastin time (PTT)40 seconds25-37 secondsFactor VIII activity35%50%-150%Platelet count225 ´ 109/L150-400 ´ 109/L What disorder is most likely?
VWD, type 1
Desmopressin acetate (DDAVP) is used to treat
VWD, type 1
What substance is used to activate protein C in the chromogenic assay to determine its concentration?
a specific snake venom
Which of the following makes a patient more prone to hemorrhage?
acute disseminated intravascular coagulation (DIC)
What is or are the possible mechanism (or mechanisms) for bleeding in patients with severe liver disease?
all of the above
Which of the following is used to treat DIC?
all of the above
Which of the following screening tests would be normal when the plasma for the patient in Question 26 is analyzed?
all of the above
What is the best test to perform if a patient's PTT does not rise after the typical heparin dose?
chromogenic antithrombin
Which of the following results puts the patient at an increased risk for thrombosis?
chronically elevated fibrinogen
Which of the following is the cause for most strokes and heart attacks in the United States?
consequences of thrombotic events
Which of the following is an expected finding in DIC?
elevated D-dimer and fibrin split products
Why does prothrombin G20210A increase the risk of thrombosis?
elevates prothrombin levels
Which of the following proteins is the best test to distinguish moderate to severe liver disease from vitamin K deficiency?
factor V concentration
In what is a patient with the following coagulation test results most likely deficient? TestTest ResultReference RangeProthrombin time (PT)17 seconds11-15 secondsPartial thromboplastin time (PTT)31 seconds25-37 secondsThrombin time (TT)16 seconds15-21 seconds
factor VII
Which of the following single-factor inherited deficiencies is most common as the cause for hemophilia?
factor VIII
A 39-year-old male patient shows evidence of poor wound healing and a history of joint bleeding. What protein deficiency is most likely present?
factor XIII
The urea solubility test is used to detect deficiencies in which factor?
factor XIII
Select the next best test to run given the following PTT results on a patient's plasma: Initial PTT:75 secondsImmediate 1:1 mix with normal plasma:38 secondsIncubated 1:1 mix with normal plasma:36 seconds
factor assays
Which of the following is decreased in DIC?
fibrinogen
All of the following can mask a deficiency of VWF and thus of type 1 VWD except
fibrinogen levels
Two children in the same family have recurrent, chronic bruising in multiple sites, repeated long-lasting epistaxis, and minor bleeding after dental work. Which type of disorder is most likely?
generalized, congenital, systemic
All of the following are associated with an increased risk of thrombosis except
high high-density lipoprotein (HDL) cholesterol
A 37-year-old female patient has a PTT of 76 seconds (reference range, 25 to 37 seconds). Her plasma is mixed 1:1 with normal plasma. An immediate PTT performed on the mix is 74 seconds. Which of the following is the most likely diagnosis?
lupus anticoagulant
What are the primary roles of VWF?
mediates platelet adhesion and carrier molecule for factor VIII
A patient who is not on heparin and has no history of a factor deficiency has a prolonged partial thromboplastin time (PTT). Select the test that should be performed next.
mixing studies for lupus anticoagulant
A patient has a quantitative D dimer of 800 ng/mL. Which can be ruled out from the following list?
patient is normal
The bleeding associated with renal disease is related most to defective
platelets.
Which of the following would be appropriate initial testing for the siblings in Question 1?
prothrombin time (PT), partial thromboplastin time (PTT), and platelet count
What is the purest form of factor VIII that is available for treating a bleeding patient with hemophilia A?
recombinant factor VIII concentrate
What is the typical clinical picture in patients with severe hemophilia A?
serious anatomic bleeds into joints
What is the best test to distinguish hemophilia A from B or C?
specific factor assays
Inappropriate formation of platelets or fibrin clots that obstructs blood vessels is called
thrombosis.
Which is the most common form of von Willebrand disease (VWD)?
type 1
