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Hematology 2 > MIDTERM: PT Determination (lab) > Flashcards

MIDTERM: PT Determination (lab) Flashcards

1
Q

A clotting time obtain when an excess of Thromboplastin and optimum calcium are added to oxalated plasma under standardized conditions

A

Prothrombin time

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2
Q

Solution/reagent used in PT

A

Simplastin

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3
Q

Simplastin, a reagent used in Prothrombin time is composed of?

A

Thromboplastin and calcium chloride

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4
Q

A tissue extract which is a component of simplastin

A

Thromboplastin

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5
Q

This is essentially a test for the formation of extrinsic thromboplastin which in turn leads to the formation of the fibrin clots

A

Prothrombin time

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6
Q

These are the factors that do not enter into the formation of extrinsic thromboplastin

A

Factors VIII, IX, and XII and platelets

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7
Q

State the principle of PT

A

The prothrombin time is the time needed for plasma to clot after adding calcium and tissue factor (brain or brain-lung extract).

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8
Q

This complex directly activates factor X

A

Plasma factor VII and tissue factor

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9
Q

Prothrombin time is most widely used measurement for monitoring patients on?

A

Coumarin therapy

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10
Q

Normal range of Prothrombin time

A

typically 10-13 seconds, depending on the thromboplastin reagent used

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11
Q

In Prothrombin time, to reconstitute the reagent what do you add?

A

distilled water (volume is indicate in the vial label)

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12
Q

In Prothrombin time, to ensure complete rehydration of the reagent what do you do?

A

Shake it vigorously

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13
Q

Proper storing of the reagent in Prothrombin time

A

Store in the original (tightly-capped) vial at 2°C - 8°C for not more than five days

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14
Q

Visibly apparent or not, this can cause prolonged prothrombin time

A

Bacterial contamination

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15
Q

To obtain the plasma in prothrombin time, how should you collect the sample?

A

Carefully mix 1 part sodium citrate with 9 parts venous blood

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16
Q

In Prothrombin time, how long do you centrifuge the blood sample?

A

No less than 1,500 rpm for at least 10 minutes (based on lab manual)

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17
Q

Standardized way of reporting PT

A

International Normalized Ratio (INR)

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18
Q

Specimen used for PT and aPTT

A

Citrated blood

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19
Q

Reagent used in PT

A

PT reagent (thromboplastin, calcium chloride, and phospholipids)

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20
Q

Use due to variations of thromboplastin reagents and to minimize the difference in PT results due to different reagent-instrument combinations

A

International Normalized Ratio (INR)

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21
Q

Why is it that calcium chloride is needed in the PT and APTT tests?

A
  • To counteract the sodium citrate and allow clotting to start. Because when blood is placed in a citrated tube, it binds to the free calcium in the blood thereby preventing the coagulation cascade from activating. By adding calcium chloride, you are replacing the missing calcium factor needed for the coagulation
22
Q

Used to perform the one stage prothrombin time (PT) test as a fundamental screening test for acquired or inherited bleeding
disorders and for the determination of the activity of coagulation facctors II, V, VII and X in human plasma

A

QuikCoag PT-HS reagent

23
Q

A fundamental screening test for acquitred inherited bleeding disorders .

A

Prothrombin Time

24
Q

Enumerate the vitamin K-dependent clotting factors that are reduced during oral anti-coagulation therapy

A
  • Factor II
  • Factor VII
  • Factor IX
  • Factor X
  • Protein C
  • Protein S
25
Q

During oral anti-coagulation therapy, PT time is?

A

Increased

26
Q

The test used for
quantiative detemination of blood clotting factors in the extrinsic (VII) and
common pathways (ll, V and X) of coaguiation

A

Prothrombin time

27
Q

Provides a source of tissue thromboplastin and
calcium that specifically activate factor Vll in the extrinsic coagulation pathway.

A

QuikCoag PT-HS reagent

28
Q

QuikCoag PT-HS reagent is a lyophilized preparation of?

A

Rabbit brain, thromboplastin, calcium chloride, buffer, and 0. 05% sodium azide as a preservative

29
Q

Reconstituted QuikCoag PT-HS reagent is stable for?

A

5 days when stored in the original container at 2°C - 8°C

30
Q

Reagent Preparation
To reconstitute the contents of the vial what do you add?

A

specified volume of PURIFIED WATER

31
Q

Reagent Preparation
After thoroughly mixing the contents of the vial, how long do you let it stand?

A

Let stand for no less than 15 minutes PRIOR to use to assure complete HYDRATION of contents

32
Q

Specimen collection and preparation for PT (according in the QuikCoag PT-HS manual)

For blood collection using syringe method, how many mL of blood do you transfer into a tube containing 1.0 mL of 3.2% or 3.8% sodium citrate solution?

A

9.0 mL of blood

33
Q

Specimen collection and preparation for PT (according in the QuikCoag PT-HS manual)

Q1: For blood collection using an evacuated blood collection tube, what is the recommended tube draw be used for coagulation tests?

Q2: And what is the ratio of blood to anticoagulant?

A

Q1: second or third tube

Q2: 9 parts blood to 1 part citrate or 9:1

34
Q

Specimen collection and preparation for PT (according in the QuikCoag PT-HS manual)

For plasma preparation, you centrifuge the tube at _________ for _____ soon after blood collection

A

2,500 x g and 15 minutes, respectively

35
Q

These are conditions in which the plasma is not suitable for coagulation testing

A
  • Plasma is clearly hemolyzed
  • Plasma contains >10,000 platelets per mm3
  • Red cells is not suitable for coagulation testing
36
Q

Plasma samples maintained at ROOM TEMP should be tested within?

A

2 hours

37
Q

How long do you pre-incubate the reconstituted QuikCoag PT-HS reagent and at what temperature?

A

Pre-incubate for at least 10 minutes at 37C

38
Q

How do you maintain the suspension of QuikCoag PT-HS reagent?

A

By magnetic stirring or mixing by inversion PRIOR to use

39
Q

How much control plasma do you place/ pipette in the test cuvette?

A

100 uL

40
Q

After adding control plasma into the test cuvette, how long do you incubate it?

A

Incubate at 37C for 1 minute

41
Q

How much pre-incubated QuikCoag PT-HS reagent do you RAPIDLY add to the test cuvette?

A

200 uL

42
Q

Differences between duplicate results should be?

A

Less than 5%

43
Q

If the difference between duplicate results is greater than 5% what do you do?

A

Repeat the test (if necessary)

44
Q

In reporting PT result, this is recommenced for use with patients undergoing anti-coagulation therapy

A

International Normalized Ratio (INR)

45
Q

The PT result may be reported as?

A
  • Seconds to form a clot
  • Ratio of patient clotting time to mean normal clotting time
  • Percent activity
  • International Normalized Ratio (INR)
46
Q

The International Committee for Standardization in Hematology and the International Committee on Thrombosis and Hemostasis have agreed on recommendations for the reporting of PT results as an?

A

International Normalized Ratio (INR)

47
Q

This is based on the international sensitivity index (ISI) of thromboplastin reagents

A

International Normalized Ratio (INR)

48
Q

What is the assigned ISI value?

A

1.0

49
Q

Lot specific international sensitivity index for the Reagent/Instrument

A

ISI

50
Q

What is the target ISI value?

A

0.90 to 1.50

51
Q

Why is it that Platelet Poor Plasma is always used in PT and APTT procedures?

A
  • To prevent platelet interference. Because we want to check the clot formed by coagulation factors not by the platelets

Hematology 2 (6 decks)

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