Lab 3 - HAEMOSTASIS Flashcards
What does haemostasis mean
Hemostasis is the name of a group of processes initiated in the body in order to stop bleeding in case of tissue and/or blood vessel injuries.
What are the Major groups of hemostasis disorders.
- Vasculopathy
- Thrombocytopathy
- Coagulopathy
What is Vasculopathy
- *The first step** of the hemostasis process
- *Decreased ability** of vasoconstriction in case of blood vessel injury
What is Thrombocytopathy
- *The second step** of haemostasis
- *Decreased ability** of platelets to aggregate and adhere to the site of injury, and formation of the primary thrombocyte-thrombus,
What is Thrombocytopenia
Decreased amount of thrombocytes in the blood
What is coagulopathy
The third and final step of haemostasis
Problems with the extrinsic-, intrinsic-, or common pathway of the coagulation cascade, which
ends with the formation of a polymerized fibrin network, which keeps thrombocyte thrombi at the site of injury,
Which test are performed by the side of the animal
1 Signs of increased bleeding tendency:
2 Capillary resistance (human medicine)
3 Bleeding time
(buccal mucosal bleeding time test, BMBTT)
4 The appearance of the first fibrin strand (clotting time)
5 The appearance of the clot (clotting time on different surfaces)
6 Clot retraction time
Where do we look for signs of increased bleeding tendency
Signs of increased bleeding tendency:
- on the skin and mucous membranes:
- *anemia**, petechia, ecchymosis,
suffusion;
in the thoracic cavity: haemothorax;
in the abdominal cavity: hemoperitoneum;
in the gastrointestinal tract: haematemesis, melena
What do you know about the Capillary resistance test
- The test is usually used in human medicine,
- Also called Rumpel-Leed-test.
- Ligarture on arm
- Check for PETECHIA on palmar side
3- 5 min
Tells us about the capillary function
Capillary function due to disease
Capillaries are fragile in case of VASCULITIS or other diseases that affect the wall of blood vessels
What does bleeding time (BT, BMBTT) depend on?
Depends on
Thrombocytic function, the Platelet count, and the Capillary function.
What is Bleeding time a test for
1. Thrombocytopenia
2. Thrombocytopathy
3. Vasopathy
NOT COAGULOPATHY
What is normal BT
3-5 min
No danger in clinical bleeding if the platelet count is above 50*10^9/L
What is Coagulation time (CT) a test for
Test for COAGULOPATHIES
In CT test what blood do we use
Fresh, native (not anticoag) whole blood sample
Not cause increased tissue factor (Factor III)
= initiates coagulation cascade
In CT what methods do you use
2 syringe method
In CT - where/how can you examin it
The appearance of Fibrin strand
CT on watch glass
CT in plastic syringe
CT in glasstube
CT in ACT tube
In CT - when does the first fibrin strand appear
Within 1-2 min
In CT - on watch glass
Treated with paraffin or wax
(scratch may initiate coagulation cascade)
Solid like gelatin
7-15min
In CT - in plastic syringe - time
10-12min
In CT - in glasstube - time
4-5 min
In CT - in ACTtube - time
3min
CT in ACT (activated clotting time) tube
SiO2 in 37 degrees –> Activates Factor XII (Hagemann, contact factor)
Factor XII activates Factor IX –> Kallikreinogen –> Kinigogen
= Fibrolytic Pathway
Move tube every 15-20sec
What is platelet (Thrombocytic) Count important for
Especially when BT, BMBTT is INCREASED
Petechia are visuable on skin or mucous membranes
Platelet (Thrombocytic) count is measured from which blood?
ANTICOAGULATED BLOOD
Na2+, K2, EDTA
Platelet (Thrombocytic) Count
Methods
3 Methods
Platelet (Thrombocytic) Count
Method 1
- 1 ml EDTA anticoagulated blood sample
- 9 ml physiological saline solution,
sedimented for 2 hours.
upper layer
Bürker chamber (hemocytometer).
count the number of platelets in 10 rectangles.
the number should be multiplied by 10^9
= number of platelets in 1 liter blood.
How can you make the process quicker in case of platelet count
the process can be made quicker if the sample in NaCl-solution is centrifuged on 1500/min.
Thrombocyte counting in
Bürker chamber is not accurate.
True or False
True
How to estimatete Platelet count with
Method 2
Platelet count can be estimated by using a blood smear.
Platelet count method 2
Magnification and count
Magnification: 1000X
Count: 20*10^9
Platelet count Method 2
This method is also very uncertain, however checking a blood smear for any purpose can be very important.
TRUE OR FALSE
TRUE
Platelet count Method 2
What does big thrombocytes tell you
The propper fuction
Platelet count Method 2
How is low thrombocytic count measured?
Automatic cell counter
Platelet count method 3
How to measure?
Platelet count can be measured by using automatic cell counters.
Platelet count Method 3
Which particles are taken as platelets
Particles of the blood between 5-30 fl volume
are taken as platelets.
Platelet count method 3
What can happen due to regenerative processes of the bone marrow
(Big platelets)
Sometimes in regenerative processes of the bone marrow, when there are many young (big) platelets circulating i.e. in case of
chronic blood loss, or physiologically in cats and in King Charles spaniels
= Average thrombocytic volume can be so high, that these big platelets are taken as red blood cells by the counter.
Platelet count method 3
Why are evaluation of blood smares important
an important step of the diagnosis of thrombocytic disorders!
Platelet count
What are the General Platelet Count
200-800 x10^9/l
What are the Major causes of thrombocytopenia:
1. decreased production of thrombocytes in the bone marrow
2. increased utilization of thrombocytes: DIC (disseminated intravascular coagulopathy)
3. increased destruction of thrombocytes : autoimmune thrombocytopenia (AITP)
4. increased sequestration of thrombocytes: in case of (chronic) splenomegaly
5. increased loss of thrombocytes: subacute/chronic bleeding
Clot Retraction Test
If you leave the blood in a ube for some hours, what will happen?
If you leave the blood clot in a tube for some hours, it will become smaller, and serum will appear around the
clot.
Clot retraction test
If you leave the blood clot in a tube for some hours, it will become smaller, and serum will appear around the
clot. But WHY?
The reason for this clot retraction is that platelets contain a contractile protein called thrombostenin,
Clot retraction test
What is Normally the volume of serum released by the clot within one hour
approx. 25% of the whole volume of the
initial clot..
How can we measure Thrombocytic function
Estimated by performing Clot Retraction time test
If the clot retraction is slower or does not
happen at all, we can suspectthrombocytopathy.
When do we use the Platelet aggregation test
When we suspect thrombocytopathy, i.e. von Willebrand disease.
Using the Platelet aggregation test what do we use, and to estimate what?
use aggregometer to estimate the aggregating ability of platelets correctly.
Platelet aggregation test
What type of blood should you prepare?
Where do you find the platelet rich plasma?
Propperties of the fluid?
We have to prepare a citrated blood sample and the
upper layer should be used for this analysis.
This is the platelet rich plasma.
This fluid is slightly opaque.
Platelet aggregation test
Which drugs causes exaggerated aggregation of platelets
ADP,
epinephrine etc.
Platelet aggregation test
What can be analysed by a spectrophotometer.
The speed and the rate of the clearing can be analysed by a spectrophotometer.
Nummerical value
Thrombocytic morphology
Size
Thrombocytes have 1-2 μm diameter.
Horses, sheep, cattles, have the smallest platelets (3-5 fl),
Dogs and swine have bigger (7-8fl),
Cats have the biggest (10-15fl) thrombocytes.
Thrombocytic morphology
Center
Edges
Center= GRANULOMER
Edges= HYALOMER
Major causes of thrombocytopathies:
- improper development of platelets,
for example because of hereditary glycoprotein deficiencies, etc.
- von Willebrand’s disease (see later)
- Uraemia, liver failure,myelo-, and/orlymphoproliferative diseases,NSAID treatment, etc.
In case of thrombocytopenia, thrombocytopathies and vasopathies
- What can we expect?
Besides normal coagulation, we cannot expect
signs of a really severe bleeding disorder
(suffusion, haematoma, haemothrorax, haemoperitoneum),
Because these are prevented by the formation of polymerized fibrin strands (fibrin thrombus) at the end of the coagulation
cascade.
In case of COAGULOPATHY
- What can we expect?
Besides normal thrombocytic and blood vessel function and normal platelet count may lead
to the aforementioned severe bleedings, and sometimes bleeding to death, because thrombocytic thrombi are not
stable without a fibrin network, and in case of a big blood vessel injury, thepower of blood flow can sweep away
the thrombocyte-thrombus from the wound!
Major alterations of the basic tests in different haemostasis disorders:
COAGULOPATHY
INCREASED CT
Normal BT, PC (platelet count) and Platelet morphology
Major alterations of the basic tests in different haemostasis disorders:
THROMBOCYOPENIA
INCREASED BT, DECREASED PC
Normal CT and Platelet morphology altered or not
Major alterations of the basic tests in different haemostasis disorders:
THROMBOCYTOPATHY
INCREASED BT
Normal CT, PC (platelet count), and Platelet morphology altered
Major alterations of the basic tests in different haemostasis disorders:
VASCULOOPATHY
INCREASED BT
Normal CT, PC (platelet count), and Platelet morphology
How do you examine Coagulopathies
By using more specific “global “tests, so that we can evaluate, which group(s) of factors are not functioning properly.
Citrated blood should be used (citrate prevents coagulation by binding
calcium ions), which means, 3,8 % Na-citrate:blood = 1:9. (Prepared tubes are commercially available, usually
blue cap)
What is the ratio of a prepared citrate sample?
3,8 % Na-citrate:blood = 1:9.
Prothrombin time (PT): When do you have to perform it
This test must be performed within 1 hour after sampling.
Prothrombin Time (PT)
Bloodsample mix
Blood samples should be mixed with 3.8% sodium
citrate in 9:1 dilution (4.5 ml of blood and 0.5 ml of Na-citrate).
Then centrifuge the samples in 3000 rpm for 10 min. and separate the (decalcinated) plasma from the sediment.
The plasma must be kept on 37 degrees.
Prothrombin Time (PT)
What does the reagent contain
The reagent (Simplastin) for PT evaluation contains:
rat uterus tissue homogenate as tissue thromboplastin (Factor III.), and CaCl2. The reagent must be kept at 37 degrees before use.
Evaluation of Prothrombin time (PT)
The evaluation can be performed by using a
1. coagulometer (see on the practical!) or in
2. test-tube.
200 μl reagent
should be mixed with 100 μl decalcinated (citrated!) plasma and the time of coagulation should be noted.
Normal Prothrombin time (PT)
Normal PT: 10-15 sec.
What does the Prothrombin time (PT) give information about
The function of the extrinsic pathway,
- because the coagulation cascade is triggered by adding tissue factor (and calcium ion) to the dacalcinated plasma sample.
Factors involved in Prothrombin time (PT) are:
VII., X., V., II., I., XIII.
Activated partial thromboplastin time (APTT):
For this test decalcinated plasma should be used similarly to PT.
True or false
True
The reagent of Activated partial thromboplastin time test (APTT) contain
The reagent (Silimat) contains rabbit brain homogenate as PF3 (platelet factor 3) and
Micronised silica as contact activator.
Activated partial thromboplastin time (APTT): The MIX
100 μl decalcinated plasma should be mixed with
100 μl reagent and
the mixture kept on 37 degrees
then 100 μl of 0.025 mmol/l CaCl2 solution should be added and from this moment the time of coagulation should be noted.
Normal Activated partial thromboplastin time (APTT):
Normal APTT: 20-30 sec..
What does the Activated partial thromboplastin time (APTT) give us information about?
The function of the intrinsic pathway
because the cascade is triggered by providing surface activation (imitating the effect of free collagen, which appears on the inner surface of the vessels in case of blood vessel injury), and adding platelet factor 3 (PF3) and Ca 2+ for the activation of factor X. (remember the
coagulation cascade!!)..
Factors involved in Activated partial thromboplastin time (APTT) are?
XI., IX., VIII., X., V., II., I., XIII.
Thrombin time (TT) depends on
Thrombin time (TT) By performing this test, **decalcinated plasma should be simply mixed** with a reagent **containing thrombin only**.
In this case coagulation time depends on the concentration of fibrinogen and Factor XIII.in the plasma.
Obviously, this test can also be used for the estimation of fibrinogen concentration (suspecting a normal factor XIII. level in
the blood).
Intrinsic pathway problem
- hemophilia A-factor VIII. deficiency;
- hemophilia B-factor IX. deficiency;
- von Willebrand’s disease)
Intrinsic pathway problem
APTT
PT
APTT increased
Extrinsic pathway problem
- Factor VII deficiency, dicumarol toxicosis - first stage)
Extrinsic pathway problem
APTT
PT
PT INCREASED
Common pathway problem
- Liver disease
- decreased. prod. of coag. factors,
- DIC, dicumarol toxicosis - second stage,
- Factor X. and/or V. and/or II. and/or I. and/or
* *XIII**. deficiency)
Common pathway problem
APTT
PT
APTT and PT INCREASED
In the early stage of dicumarol (or warfarin) toxicosis both APTT and PT is increased,
True or false
False
In the early stage of dicumarol (or warfarin) toxicosis only PT is increased,
In the early stage of dicumarol (or warfarin) toxicosis only PT is increased, and later APTT is increased, too.
True or false
True
What is the competitive antagonist of vitamin K.
Dicumarol
What is VIT D responsible for
- *Gamma-carboxylation** of:
- *1. Proconvertin** (Factor VII),
2. Christmas (Factor IX),
3. Stuart-Prower (Factor X) and the
4. Prothrombin (Factor II), as
they are Ca2+ dependent factors,
Vitamin K deficiency causes ?
The inability of these factors to bind calcium.
Which factor will be deficient first.
Factor VII. has the shortest half life, so this factor will be deficient first.
Which test will show the deficiency problem first.
When the Prothrombin Time is increased when
there is factor VII deficicency, so this test will show the problem first.
What is the Function of Vitamin K
To exaggerate the post-synthetic gamma-carboxylation of those factors in the liver.
This makes these factors to be able to bind Ca2+, and thus become
functionally active.
In case of vitamin K deficiency of any origin, improperly carboxylised prothrombin can be detected by using ?
ELISA (Enzyme Linked Immunosorbent Assay) test, called PIVKA II. (Proteins Induced by Vitamin K Absence)
Fibrin degradation products (FDP)
What is Fibrinolytic pathway is responsible for
The Fibrinolytic pathway is responsible for keeping the clot formation within normal limits.
What are the Clot inhibitors
(antithrombin III., alpha2-macroglobulin, alpha1-antitripsin, heparin – the latter increases the binding of antithrombin III to thrombin)
are able to bind to thrombin and neutralize it.
After complete coagulation, the clot is usually not needed anymore, so it should be broken down by …….
fibrinolytic enzymes.
What are the activators of factor XII. (Hageman).
1. Free collagen fibres, (exposed at the site of blood vessel injury),
2. kininogen and
3. kallikrein are the activators of factor XII. (Hageman).
XII.a (activated form of factor XII. ) further activate
the extrinsic pathway,
XII.a (activated form of factor XII. ) further activates the extrinsic pathway and is able to form…….
kallikrein from prekallikrein.
- *Kallikrein** activates the kininogen system, also, forming
- *Bradykinin** (an activated form of kininogen), which is a very potent mediator of pain.
What is an activated form of kininogen, and what is it a strong mediator for?
Bradykinin (an activated form of kininogen), which is a very potent mediator of pain.
What is the most
important activator of plasminogen.
Kallikrein
What is the activated form of plasminogen?
- *Plasmin** (activated form of plasminogen) is an endopeptidase, which can
- *cleave fibrin strands into small pieces.**
\
Before the total degradation of polymerized fibrin strands, increased
level of
fibrinolysis-products, fibrin dimers and monomers (so called: “fibrin degradation products or proteins,
FDP”) can be measured in the blood.
What is the fuction of FDP
Fibrinolyticenzyme removes clot - elevates level of FDP
but its not accurate because the degradation product could come from both - fibrinogen/fibrin
What to use instead of FDP ?
D-Dimer level
To distinguish btw fibrin and not fibrinogen
What is helpfull with D-Dimer
Helpful in early diagnosis of disseminated Intravascular coagulopathy (DIC)
What is DIC
DIC is a common acute disorder
(that requires accurate and quick laboratory diagnosis)
Usually a secondary disease, caused by primary diseases
LIFETHREATHENING
Name some primary causes that could have caused DIC
Septicemia
Pancreatitis
Burn injuries
Necrosis of big tumors
Shock
Polytraumatisation
What could be the first sign of DIC
Positive FDP or D-dimer test
What is present simultaneously many places in the body during DIC
Formation of Microthrombus + Fibrinolysis
Because of severe damage(necrosis) or Blood vessel injuries
What is “consumptional coagulopathy”.
In case of DIC, microthrombus formation and fibrinolysis are
present at many different places in the body simultaneously, so coagulation factors and platelets are consumed very quickly during this process.
What happens during Consumptional Coagulopathy
Coagulating factors and platelets are consumed
Lab DIAGNOSIS of DIC
CT, BT, Platelet count, PT, APTT and TT?
FDP and D-Dimer?
SCHYSOCYTES and/Or BURR CELLS
INCREASED
CT, BT, PT, APTT and TT
FDP and D-Dimer
DECREASED
Platelet count
SCHYSOCYTES and/Or BURR CELLS
in blood smare = damaged red blood cells
Diagnosis of Von WILLEBRAND Disease
Which species
Human and dog (Dobberman Pincher)
Diagnosis of Von WILLEBRAND Disease
Which factor is deficient
Von Willebrand factor
FACTOR VIII is deficient
Diagnosis of Von WILLEBRAND Disease
What are the 3 main parts of complete factor VIII
- Von Willebrand factor – platelet adhesion and aggregation,
- VIIIc – is the antihemophilic factor, and the
-
Factor VIII related antigen – is the hapten that is the determinable
part, and is bound strongly to von Willebrand factor.
How does BT(BMBT), Clot reaction ability look like in the case of a dog with VON WILLEBRAND DISEASE
INCREASED
BT, BMBT
DECREASED
Clot reaction ability
Coagulation disorder sometimes
The specific diagnosis of VON WILLEBRAND DISEASE is based upon
The detection of the lack of von Willebrand-related antigen.
What happens to BT, Platelet count, APTT and PT due to
THROMBOCYTOPENIA
BT is INCREASED,
Platelet count is DECREASED
APTT and PT = Unchanged
What happens to BT, Platelet count, APTT and PT due to
THROMBOCYTOPATHY
BT is INCREASED,
Platelet count, APTT and PT is UNCHANGED
What happens to BT, Platelet count, APTT and PT due to
- *Intrinsic pathway disorder**
(pl. haemophilia A, B)
INCREASED APTT
BT, Platelet count and PT is unchanged
What happens to BT, Platelet count, APTT and PT due to
Factor VII Deficiency
Factor VII Deficiency (in early phase of DICUMAROL toxicosis)
PT is INCREASED
BT, Platelet count and APTT is unchanged
What happens to BT, Platelet count, APTT and PT due to
Disorders of the common pathway
Disorders of the common pathway
(Liver faiure, Factor X deficiency, late stage of DICUMAROL toxicosis)
BT is unchanged or INCREASED,
APTT and PT is INCREASED
The platelet count is unchanged
What happens to BT, Platelet count, APTT and PT due to
DIC
BT, APTT and PT is INCREASED
Platelet count is DECREASED
What happens to BT, Platelet count, APTT and PT due to
VON WILLEBRAND-DISEASE
BT is INCREASED
APTT is unchanged or INCREASED
Platelet count and PT is unchanged