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Hematology > APTT and PT - lab > Flashcards

APTT and PT - lab Flashcards

1
Q

QuickCoag APTT-EA reagent, in vitro or in vivo?

A

in vitro

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2
Q

APTT is a general screening test for the detection of coagulation abnormalities in the ___

A

intrinsic pathway

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3
Q

APTT is sensitive to deficiencies or abnormalities of factors ___

A

II, VIII, IX, X, XI, XII, prekallikrein, HMWK, fibrinogen

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4
Q

APTT: inhibitors of blood coagulation

A

lupus inhibitor and fibrin/fibrinogen degradation

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5
Q

APTT is most widely used method for monitoring __

A

intravenous heparin anticoagulation therapy

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6
Q

principle of APTT

A

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.

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7
Q

APTT reagent is a preparation of __ and ___ activator with buffer stabilizers, and preservatives.

A

rabbit brain and ellagic acid

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8
Q

APTT reagent should be stored in what temp?

A

2-8 C

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9
Q

specimen for APTT is the citrated whole blood without?

A

heparin, EDTA, or oxalate

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10
Q

syringe method: draw venous blood into a plastic or siliconized syringe. immediately transfer __ of blood into a tube containing ___ of __ sodium citrate solution

A

9 ml of blood
1 ml of 3.2% or 3.8% sodium citrate

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11
Q

blood to anticoagulant ratio of sodium citrate

A

9:1

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12
Q

t or f: it is recommended that the second or third draw be used for coagulation tests

A

true

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13
Q

plasma preparation: mix well by inversion and centrifuge at ___ for ___ mins soon after blood collection.

A

2,500 x g for 15 mins

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14
Q

specimen that is not suitable for coagulation testing

A

hemolyzed plasma or plasma that contains >10, 000 platelets or red cells

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15
Q

APTT procedure: manual, semi automated, or automated

A

manual or semi-automated

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16
Q

PROCEDURE OF APTT

  1. pre-incubate the __ to __ for at least __ minutes
  2. Pipette __ of test or __ into a test cuvette. incubate at __ for __ mins.
  3. 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.
  4. incubate the mixture at __ for __ mins.
  5. rapidly add __ of the ___ and simultaneously start the timer.
  6. record the clotting time in seconds.
A
  1. pre-incubate the calcium chloride 0.02 M to 37C for at least 10 minutes
  2. Pipette 100 uL of test or control plasma into a test cuvette. incubate at 37C for 1-2 mins.
  3. 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.
  4. incubate the mixture at 37C for 3 mins.
  5. rapidly add 100 uL of the pre-incubated calcium chloride and simultaneously start the timer.
  6. record the clotting time in seconds.
17
Q

samples that can produce erroneous APTT results

A
  • lipemic samples
  • hemolysed
18
Q

APTT result: venipuncture above the site of a heparin lock.
falsely increase or decrease

A

falsely increased

19
Q

NV of APTT

A

24-39 secs (sa pdf)
35-45 secs (sa ppt)

20
Q

things to do in performing coagulation testing

A
  • 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
21
Q

factor/s that breaks at more than 37C or room temp

A

factor V and VIII

22
Q

NV of PT

A

10-13 secs

23
Q

specimen for PT

A

citrated blood (heavy spin, centrifuge for 10 mins to yield PPP)

24
Q

PT reagent

A
  • thromboplastin
  • calcium chloride
  • phospholipids
25
Q

standardized way of reporting PT

A

International normalized ratio

26
Q

why INR is used?

A

due to variations of thromboplastin reagents

27
Q

why INR is introduced?

A

to minimize the difference in PT results due to different reagent-instrument combinations

28
Q

APTT reagents

A
  • thromboplastin
  • activator (kaolin, ellagic acid, celite)
  • calcium chloride
  • phospholipids
29
Q

measures the ability of functional fibrinogen

A

thrombin time

30
Q

TT is to determine the rate of thrombin-induced cleavage of?

A

fibrinogen to fibrin monomers

31
Q

TT reagent

A

thrombin reagent and calcium chloride

32
Q

steps of TT

A
  1. add around 0.2 plasma in a plastic or siliconized glassware and warm in water bath at 37C
  2. mix with reagent and start stopwatch
  3. stop the watch when clot formation is visible
33
Q

NV of TT

A

15-18 secs

34
Q

thrombin is prolonged in?

A
  • fibrinogen deficiency
  • presence of fibrin degradation products
  • presence of thrombolytic agent
  • presence of heparin
  • presence of streptokinase
35
Q

test used for factor XIII deficiency

A

Ducker’s test

36
Q

reagent for ducker’s test

A

5m urea (1% monochloroacetic acid, 2% acetic acid)

37
Q

steps of ducker’s test

A
  1. 0.2 of calcium chloride is added to 0.2 PPP and incubate at 37C for 30 mins.
  2. transfer the clot in another tube with 5mL 5M urea.
  3. observe for dissolving clot in 1,2,3, and 24 hours.
38
Q

normal for ducker’s test

A

clot is insoluble to urea

Hematology (4 decks)

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