P2: Laboratory Flashcards
Sample of clotting time (Lee and white method)
Venous blood
In clotting time (Lee and white method) the _______ are the best for there is less contamination of the plasma with tissue fluids when blood is drawn from a vein through venipuncture.
Test tube methods
Sources of error in clotting time (Lee and white method)
- Dirty test tube
- Tissue juices mixed with blood
- Air bubbles in the blood due to faulty venipuncture
- Excessive agitation of blood
- Temperature below 35C and above 45C retards coagulation
- Diameter of test tubes, the smaller the diameter the more rapid the clot formation
Normal value of clotting time (Lee and white method)
5 - 15 mins
In clotting time (Lee and white method), is clothing time is more than 15 mins, it indicates a
Deficiency in blood coagulation components
This is a another method of clothing time which uses plain capillary tubes.
CLOOTING TIME (CAPILLARY TUBE METHOD BY SABRAZE’S)
What is the end product of CLOTTING TIME (CAPILLARY TUBE METHOD BY SABRAZE’S)
Formation of fibrin
Normal capillary clotting time of CLOTTING TIME (CAPILLARY TUBE METHOD BY SABRAZE’S)
3-7 minutes
In CLOTTING TIME (CAPILLARY TUBE METHOD BY SABRAZE’S), the puncture depth is
3mm
This method is the simplest among all the methods in clotting time
Clotting time (Slide or Drop Method)
This method uses clean slide
Slide or Drop Method
Normal capillary clotting time for Slide or Drop Method
2-4 minutes
In APTT, what is the role of the calcium
The calcium in whole blood is bound by the sodium citrate anticoagulant to prevent anticoagulation
In APTT, after centrifugation, the plasma contains
The plasma contains all intrinsic coagulation factors except calcium and platelets
What is the activated partial thromboplastin time
The time required for the plasma to clot
Normal clotting time for APTT
23-40 seconds
In APTT, what is the concentration for the substitute for platelets
Calcium chloride, 0.025 M
Is the most frequently performed tests for coagulation that evaluates the function of the extrinsic and common pathways of hemostasis
Prothrombin Time (PT)
PT is used not only as a coagulation screening test, but also
To monitor oral anticoagulant therapy
PT is especially effective for
Monitoring patients receiving coumarin
PT is also dependent upon factors such as
I, II, V, VII, and X
It is used means for measuring the effect of anticoagulant
Prothrombin Time (PT)
Principle of PT
The PT test is performed by adding tissue extract (Factors III = tissue factors) and calcium to the plasma. This initiates the activation of factor VII. Activated factor VII in turn, activated thrombin will then convert fibrinogen into fibrin
Normal value in PT
11-13 seconds
Prothrombin index:
PT of control
——————- x 100
PT of test
Prothrombin ratio
PT of test
——————
PT of control
Principle of Fibrinogen Degradation Products (FDP)
Thrombo-Wellcoltest Procedure
Whole blood is added to Thrombo (to ensure complete clotting) and soya beans enzyme inhibitors (to prevent breakdown of fibrin). After complete clotting, the patient’s serum is diluted and mixed with latex particles coated with anti-FDP (fibrinogen fragment D & E). If fibrinogen degradation products are present, agglutination of the latex particles will occur.
In FDP, if the patient is receiving heparin
Reptilase- should be added to the patient blood in the sample collection tube in order to complete clotting occur
Buffer used in FDP
Glycine saline buffer
