APTT and PT - lab Flashcards
QuickCoag APTT-EA reagent, in vitro or in vivo?
in vitro
APTT is a general screening test for the detection of coagulation abnormalities in the ___
intrinsic pathway
APTT is sensitive to deficiencies or abnormalities of factors ___
II, VIII, IX, X, XI, XII, prekallikrein, HMWK, fibrinogen
APTT: inhibitors of blood coagulation
lupus inhibitor and fibrin/fibrinogen degradation
APTT is most widely used method for monitoring __
intravenous heparin anticoagulation therapy
principle of APTT
the capacity of blood to form a fibrin clot by way of the intrinsic hemostatic pathway requires coagulation factors I, II, V, VIII, IX, X, XI, and XII, platelet lipids and calcium. The assay is performed by the addition of a suspension of rabbit brain cephalin with a surface activator. The APTT has proven to be the simple and highly reliable measurement of the intrinsic coagulation mechanism.
APTT reagent is a preparation of __ and ___ activator with buffer stabilizers, and preservatives.
rabbit brain and ellagic acid
APTT reagent should be stored in what temp?
2-8 C
specimen for APTT is the citrated whole blood without?
heparin, EDTA, or oxalate
syringe method: draw venous blood into a plastic or siliconized syringe. immediately transfer __ of blood into a tube containing ___ of __ sodium citrate solution
9 ml of blood
1 ml of 3.2% or 3.8% sodium citrate
blood to anticoagulant ratio of sodium citrate
9:1
t or f: it is recommended that the second or third draw be used for coagulation tests
true
plasma preparation: mix well by inversion and centrifuge at ___ for ___ mins soon after blood collection.
2,500 x g for 15 mins
specimen that is not suitable for coagulation testing
hemolyzed plasma or plasma that contains >10, 000 platelets or red cells
APTT procedure: manual, semi automated, or automated
manual or semi-automated
PROCEDURE OF APTT
- pre-incubate the __ to __ for at least __ minutes
- Pipette __ of test or __ into a test cuvette. incubate at __ for __ mins.
- add __ of the APTT reagent to the cuvette containing the plasma. maintain the suspension of the reagent by magnetic stirring or mixing by inversion immediately prior to use.
- incubate the mixture at __ for __ mins.
- rapidly add __ of the ___ and simultaneously start the timer.
- record the clotting time in seconds.
- pre-incubate the calcium chloride 0.02 M to 37C for at least 10 minutes
- Pipette 100 uL of test or control plasma into a test cuvette. incubate at 37C for 1-2 mins.
- add 100 uL of the APTT reagent to the cuvette containing the plasma. maintain the suspension of the reagent by magnetic stirring or mixing by inversion immediately prior to use.
- incubate the mixture at 37C for 3 mins.
- rapidly add 100 uL of the pre-incubated calcium chloride and simultaneously start the timer.
- record the clotting time in seconds.
samples that can produce erroneous APTT results
- lipemic samples
- hemolysed
APTT result: venipuncture above the site of a heparin lock.
falsely increase or decrease
falsely increased
NV of APTT
24-39 secs (sa pdf)
35-45 secs (sa ppt)
things to do in performing coagulation testing
- non-traumatic blood collection
- follow the order of draw
- always check for the presence of clots
- use only plastic tubes or silicone-coated glass tubes
- observe the blood to AC ratio
- specimen should be centrifuged within 1 hr
- required temp: 37C
factor/s that breaks at more than 37C or room temp
factor V and VIII
NV of PT
10-13 secs
specimen for PT
citrated blood (heavy spin, centrifuge for 10 mins to yield PPP)
PT reagent
- thromboplastin
- calcium chloride
- phospholipids
standardized way of reporting PT
International normalized ratio
why INR is used?
due to variations of thromboplastin reagents
why INR is introduced?
to minimize the difference in PT results due to different reagent-instrument combinations
APTT reagents
- thromboplastin
- activator (kaolin, ellagic acid, celite)
- calcium chloride
- phospholipids
measures the ability of functional fibrinogen
thrombin time
TT is to determine the rate of thrombin-induced cleavage of?
fibrinogen to fibrin monomers
TT reagent
thrombin reagent and calcium chloride
steps of TT
- add around 0.2 plasma in a plastic or siliconized glassware and warm in water bath at 37C
- mix with reagent and start stopwatch
- stop the watch when clot formation is visible
NV of TT
15-18 secs
thrombin is prolonged in?
- fibrinogen deficiency
- presence of fibrin degradation products
- presence of thrombolytic agent
- presence of heparin
- presence of streptokinase
test used for factor XIII deficiency
Ducker’s test
reagent for ducker’s test
5m urea (1% monochloroacetic acid, 2% acetic acid)
steps of ducker’s test
- 0.2 of calcium chloride is added to 0.2 PPP and incubate at 37C for 30 mins.
- transfer the clot in another tube with 5mL 5M urea.
- observe for dissolving clot in 1,2,3, and 24 hours.
normal for ducker’s test
clot is insoluble to urea
