Module 1 Laboratory Flashcards
All of the following are obsolete tests except:
A. Bleeding time
B. Capillary fragility test
C. Blood clot retraction time
B
Capillary/tourniquet test is used for
dengue hemorrhagic fever
Process of cessation/stopping of bleeding
Hemostasis
Bleeding is stopped by
clot formation
Unwanted / excessive formation is prevented by
inhibitors
Key player in primary hemostasis
platelets
Key player in secondary hemostasis
coagulation proteins, at least 16
Product of primary and secondary formation
clot formation
If clot formation and clot dissolution is not balanced, this may cause
aneurysm (embolus)
It retards or stops a process or chemical reaction
inhibitors
A blood clot that obstructs a blood vessel
thrombus
A mass (clot) of blood or foreign matter carried in circulation
embolus
Process of forming a fibrin clot
coagulation
Enzymatic breakdown of blood clot
fibrinolysis
Under secondary hemostasis, produces stable fibrin clot
Coagulation cascade
What are the 3 pathways in coagulation cascade?
extrinsic
intrinsic
common pathway
Clot dissolution is also known as
fibrinolysis
Abnormal thickening and hardening of arterial walls, causing loss of elasticity and impaired blood circulation
Arteriosclerosis
A form of arteriosclerosis in which lipids, calcium, cholesterol and other substances deposit on the inner walls of the arteries
Atherosclerosis
2 major parts of physiologic hemostatic system
cellular component
plasma proteins
Enumerate cellular components
Platelets
ECs
Neutrophils
Monocytes
Group of plasma proteins which participates in
Clot formation (coagulation) Clot dissolution (fibrinolysis) Naturally occurring serine protease inhibitions (anti-coagulation)
activation happens before
platelet adhesion
Has platelet adherence to nonplatelet surface (platelet to subendothelial) through VWF (glue)
platelet adhesion
Membrane receptor in platelet adhesion
GP1b/IX/V
found in endothelial tissue, Weibel-Palate.
VWF (von Willebrand factor)
VWD disease types
1,2,2n
If GP1B is defective/missing, there will be
BSS (Bernard soulier syndrome)
platelet to platelet bonding
Platelet aggregation
membrane receptor for Platelet aggregation
GP IIIa/IIb
Acts as glue during platelet aggregation
fibrin
If GP2B is defective/missing, what diease
Glanzmann Thrombasthenia
If fibrinogen is missing
Afibrinogenemia (absent)
Hypofibrinogenemia (decrease)
Dysfibrinogenemia (defective fibrinogen)
- secretion of granules. Happens at late stages of platelet activation process.
Platelet secretion
If alpha granules are defective/missing
gray platelet syndrome (genetic defect)
If dense granules are defective/missing
May-Hegglin Anomaly
can also trigger activation in intrinsic factor
collagen
links platelet to subendothelial collagen
VWF
promotes platelet adhesion
VWF
It activates neighboring platelets
ADP
Acts as vasoconstrictor
serotonin
Enumerate those under alpha granules
beta-thromboglobulin factor V factor XI protein S fibrinogen VWF Platelet factor 4 Platelet derived growth factor
Enumerate those under dense granules
ATP
ADP
Calcium
Serotonin
Absent GP IIb/IIIa platelet membrane receptor
Glanzmann thrombasthenia
This test suggests the bleeding history
platelet count
When there is bleeding history, this test is needed
platelet function test
Reflects the platelet function
bleeding time
an infrequently performed in vivo measurement of platelet adhesion and aggregation on locally injured vascular sub-endothelium
Bleeding time
Provides an estimate of the integrity if the platelet plug
bleeding time
Measure the interaction between the capillaries and platelets
bleeding time
How many incisions are made in bleeding time
two incision
Use of lancet to make a small, controlled puncture wound (earlobe or fingertip)
duke’s method
Puncture site is blotted with filter paper every 30 seconds until the bleeding stops
duke’s method
In duke’s method of bleeding time, puncture site is blotted every
30 seconds
reference interval for duke’s method is
2-9 minutes
A blood pressure cuff is inflate to 40mmHg
standardized/modified ivy method
in modified ivy method, blood pressure cuff is inflated to
40mmHg
A calibrated spring-loaded lancet was triggered on the volar surface of the forearm a few inches distal to the antecubital crease
standardize/modified ivy
reference interval for standardize/modified ivy
2-9 minutes
Capillary fragility test also known as
rumpel-leede
tourniquet
defined as necessary requisites for diagnosis of dengue fever
capillary fragility test
A blood pressure cuff is applied and inflated to a point between the systolic and diastolic blood pressure for 5 minutes
capillary fragility/tourniquet/rumpel-leede test
positive result in capillary fragility test
10 or more petechiae per square inch
positive result for dengue hemorrhagic fever in capillary fragility test
20 or more petechiae per square inch
this test does not have high specificity
capillary fragility test
Capillary fragility test is only ______ test
screening
confirmatory test for dengue hemorrhagic fever
NS1Ag
In tourniquet test, after maintaining the point midway for 5 minutes, you have to reduce and wait for how many more minutes
2 mins
In tourniquet test, count petechiae in what area
below the antecubital fossa
Degree of clot retraction is
A. inversely proportional to number of platelets and directly proportional to hct and fibrinogen level
B. directly proportional to number of platelets and inversely proportional to hct and fibrinogen level
C. equal to hct and fibrinogen level
D. slightly higher than number of platelets
B
It evaluates how well platelets keep the clot adhered to the sides of specimen tube
clot retraction
Clot retraction uses what specimen and what tube
whole blood in red top tube
Clot retraction examine clot at _, _, _ and _ hours for clot retraction
1, 2, 4, 24 hours
During clot retraction, clot starts to shrink at _____.
30 minutes
After clot forms, remaing _ - _% consists of ____ and ____ will _____ from clot
40-60
serum and rbc
fall out
In order for clot retraction test to be accurate, there should be
normal fibrinogen and hematocrit
adherence of platelets to glass surface
platelet adhesion
counting the number of platelets before and after exposure to glass beads
platelet adhesion
not a reliable method
platelet adhesion
platelet adhesiveness to glass beads, diagnosis of VWD
salzmann method
Results in platelet adhesion
> 25% - normal (75), retain
<25% - abnormal/prolonged, retain
Based on some variation of born method
platelet aggregation
Platelet aggregation principle
PRP is treated with known aggregating agents
This will indicate aggregation
cloudy or turbidity
Cloudiness or turbidity can be measure by
spectrophotometer
As aggregation proceeds in spectrophotometer what will happen
more light passes through the sample
Enumerate aggregating agents
ADP Collagen Epinephrine Snake venom Thrombin Ristocetin
Measures VwF
ristocetin cofactor assay
mediated agglutination of platelets in the presence of antibiotic (ristocetin)
ristocetin cofactor assay
Most commonly used assay for measurement of functional activity of VWF
ristocetin cofactor assay
Introduced as an alternative procedure for RCo assay
Collagen-binding ELISA
In collagen-binding ELISA, this servers as a marker of endothelial dysfunction
vWF-antigen
Antibodies against platelet may appear in certain clinical conditions
Anti-platelet antibody assays
Antibodies are difficult to demonstrate in case of immune thrombocytopenia
Ant-platelet antibody assays
