Here’s a little coagulation quiz to start your morning.
1. Which of the following initiates the coagulation cascade IN VIVO?
A. Factor XII
B. Thrombin
C. Tissue factor
D. Factor X
E. Prekallikrein
2. What does von Willebrand factor do?
A. Binds platelets to each other
B. Binds platelets to the subendothelium
C. Binds platelets to the phospholipid surface
D. Carries factor VII
E. Cleaves factor V
3. Which of the following is true?
A. The extrinsic system is activated first, and then the intrinsic system is turned on later
B. The intrinsic system is weak and short-lived
C. The extrinsic system is only important in vitro
D. Factors V and VII are only important in vitro
4. Which of the following anti-clotting substances acts on factors V and VIII?
A. ATIII
B. Protein C
C. TFPI
D. Plasmin
E. t-PA
5. Which of the following is a cofactor?
A. XII
B. X
C. VIII
D. VII
E. II
6. What are the ingredients in a PTT?
A. Â Plasma + phospholipid + calcium
B. Plasma + thromboplastin + calcium
C. Plasma + phospholipid + thromboplastin
D. Plasma + thrombin + calcium
E. Plasma + plasmin + calcium
7. Which test evaluates the extrinsic pathway?
A. PT (INR)
B. PTT
C. TT
D. Closure time
E. Bleeding time
8. Which of the following is true regarding the bleeding time?
A. It is a highly reliable and reproducible test
B. The sample is evaluated using an optical densitometer
C. It evaluates platelet function in vivo
D. It is a commonly ordered test
E. It evaluates the coagulation system
9. What is the most common inherited bleeding disorder?
A. von Willebrand’s disease
B. Hemophilia A
C. Hemophilia B
D. Factor V Leiden
E. TTP
10. Which disorders may show “factor-type” bleeding?
A. von Willebrand’s disease
B. Hemophilia A
C. Both
D. Neither
11. Patients with which of the following diseases may have a normal PTT?
A. von Willebrand’s disease
B. Hemophilia A
C. Hemophilia B
D. Factor V Leiden
12. TTP:
A. May present with CNS deficits
B. Is caused by a toxin produced by E. coli
C. Is treated supportively
D. Does not show a microangiopathic blood picture
Answers: 1. C, 2. B, 3. A, 4. B, 5. C, 6. A, 7. A, 8. C, 9. A, 10. C, 11. A,D 12. A
The gorgeous photo of Leiden (as in Factor V Leiden) was taken by Motumboe (http://www.flickr.com/photos/motumboe/2709667509/).
The quiz was really helpful. Thanks!
Number 9 is incorrect, it’s B. Hemophilia A
Von Willebrand disease (a hereditary bleeding disorder) has an incidence as high as 1 in 100 (according to some sources). The incidence of hemophilia A is about 1 in 10,000. If the question had asked about the most common hereditary factor deficiency, however, Hemophilia A would be correct.
Unrelated to the quiz but felt like sharing my experience with a patient with Factor V Leiden. He had multiple AMIs since 30s, a TIA and later a stroke, severe peripheral vascular disease requiring extensive bypass and came with what later turned out to be PE. Strong family history for this guy and he has been on warfarin since a young man. He seemed to think that was all normal (seriously).
Also I encourage people who are not familiar with the Cell-Based Model of Haemostasis to look it up and appreciate how it describes coagulation in the body more accurately than the cascade model we are so used to which as far as I can tell more adequately describes the laboratory process.
Thanks for your comment, Kevin! It’s always good to hear about a real patient’s experiences – it makes the disease so much more real. Thanks also for mentioning the cell-based model of coagulation. Fascinating how our understanding of coagulation keeps changing!
I have developed a more reality-based cascade of coagulation. Although a bit detailed, one can find many different diagrams combined in a single page.
Plus it avoids the typical extrinsic and intrinsic Y-shaped model of haemostasis.
If any one wants to add something, one is highly welcome. 🙂
http://haematologywatch.net/forum.php#/20111204/coagulation-cascade-1070962/
Thanks Dr. Mehmood-ul-Hasan!
Question no 6.
Ingredients in PTT….
Plz Explain it.
Here’s a post that explains the ingredients in the PTT.
What is the difference between
Inherited
and
Heriditary ?
Dr.Kristine
Hi Mahesh – The words inherited and hereditary mean the same thing.