module 1 Flashcards
3 mL of the blood is taken, and 1 mL of the blood is in each test tubes. Start two stopwatches as you see the blood in the syringe. Keep the blood in the water bath and check for clotting by tilting each tube at intervals of 30 to 60 seconds. Tilt the tube to greater than 90 degrees
Lee- White method
NV of Lee- White method
blood clots firmly within 4-8
minutes
This test is used to monitor heparin
therapy which prolongs the clotting
time.
Lee- White method
The procedure is carried out at 37 deg Celsius and the tube is tilted after the first minute and thereafter 5-10 seconds intervals until the clot is formed.
Activated coagulation time
NV - Activated coagulation time
coagulation time is complete in
less than 101 seconds
Reagents used in Prothrombin time
Thromboplastin and ionized calcium
when the reagents are added to citrated plasma, these substitute for tissue factor activates factor X in the presence of factor VII involving platelets or procoagulants in the intrinsic pathway.
Prothrombin time
NV - Prothrombin time
10-12 sec
Prolongation of PT when PTT is
normal, occurs only in
factor VII deficiency
Prolonged PT and and PTT occurs in
oral anticoagulation therapy, liver disease, Vit K deficiency and def of
common pathway
compares the local thromboplastic reagent against
international reagent
International normalized ratio (INR)
A normal INR is
1.0.
A normal INR is 1.0. Each increase
of 0.1 means
the blood is slightly
thinner (it takes longer to clot).
INR is related to the
prothrombin time (PT).
If there is serious liver disease and
cirrhosis, the liver may
the liver may not produce
the proper amount of proteins and
then the blood is not able to clot as it
should.
The test is performed in a citrated
blood.
Activated partial thromboplastin time
The plasma is recalcified.
Activated partial thromboplastin time
enhances the speed of contact
activation
Kaolin
provides a surface on
which coagulation enzyme substrate
can occur
Phospholipid
NV - Activated partial thromboplastin time
28-40 sec
assess the intrinsic
coagulation pathway
Activated partial thromboplastin time
APTT assess the intrinsic
coagulation pathway except
factor VII and platelets.
Performed exactly the same as APTT
except that an activator is not included
in the thromboplastin reagent.
Partial thromboplastin time
NV - Partial thromboplastin time
40- 100 sec
is a thromboplastin like
substance that activates factor X.
Stypven
When this reagent is added together
with platelets and CaCl2, the
coagulation process has begun at the
point of factor X activation.
Stypven
Stypven time is used to detect
It is used to detect deficiencies in
prothrombin, fibrinogen, factor X and
factor V.
Stypven time also called as
Russell’s viper venom time
it is an enzyme that is found
in the venom of the Bothrops atrox
snake
Reptilase
It is capable of converting
fibrinogen to fibrin and is not affected
by heparin.
Reptilase time
A measured amount of thrombin is
added to plasma. The legth of time for
a fibrin clot to form is recorded as
thrombin time.
Thrombin time
It measure the availability of
functional fibrinogen .
Thrombin time
Prolonged thrombin time is found if
fibrinogen level is
low (below 75- 100 mg/dl)
Patients with fletcher factor
deficiency will have a prolonged ———
APTT.
If the plasma + APTT reagent mixture is incubated for 10 minutes, the prolonged APTT will be shortened to normal or almost normal if the deficiency is due to
fletcher factor
If the plasma + APTT reagent
mixture is incubated for 10 minutes,
the prolonged APTT will be
shortened to normal or almost
normal
