Prothrombin Time (F)

Question 1

What are the purposes of PT?

Answer 1

1) Tests the efficiency of extrinsic and common pathways in vitro
2) Monitors the effects of warfarin therapy
3) Best indicator of vitamin K deficiency

Question 2

What is the simplified process (or steps) of PT?

Answer 2

1) PPP + tissue factor (TF) + phospholipid
2) Incubate at 37 DC
3) + Calcium
4) Record clotting time

Question 3

What is the composition of PT rgnt?

Answer 3

Tissue thromboplastin + phospholipids + ionized calcium

Question 4

What is the purpose of tissue thromboplastin?

Answer 4

It substitutes for the tissue factor for extrinsic pathway in vivo

Question 5

What is the characteristic of tissue thromboplastin?

Answer 5

It could be:

1) Recombinant
2) Purified
3) Organic (emulsified rabbit brain or rabbit lung)

Question 6

What is the characteristic of PT rgnt?

Answer 6

It is often in lyophilized form

Question 7

What are the diff methods for PT?

Answer 7

1) Manual method
2) Semi-automated method
3) Automated method
4) POCT method

Question 8

What are the characteristics (in terms of process) of manual method?

Answer 8

1) Uses test tubes
2) Uses H2O bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Manual timer
6) Manual incubation
7) Manual computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using our own eyes

Question 8

What are the characteristics (in terms of process) of manual method?

Answer 8

1) Uses test tubes
2) Uses H2O bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Manual timer
6) Manual incubation
7) Manual computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using our own eyes

Question 8

What are the characteristics (in terms of process) of manual method?

Answer 8

1) Uses test tubes
2) Uses H2O bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Manual timer
6) Manual incubation
7) Manual computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using our own eyes

Question 8

What are the characteristics (in terms of process) of manual method?

Answer 8

1) Uses test tubes
2) Uses H2O bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Manual timer
6) Manual incubation
7) Manual computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using our own eyes

Question 8

What are the characteristics (in terms of process) of manual method?

Answer 8

1) Uses test tubes
2) Uses H2O bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Manual timer
6) Manual incubation
7) Manual computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using our own eyes

Question 9

What is the process (or steps) of manual method?

Answer 9

1) Reconstitute PT rgnt by adding PT diluted or distilled H2O into the rgnt bottle. Incubate at 37 DC
2) Transfer 50 - 100 uL of citrated PPP into a tube / cuvette. Incubate this aliquot at 37 DC for 3 mins
3) Add 100 - 200 uL of warmed PT rgnt directly to the warmed citrated PPP
4) Start timer. Record the time until visible clot formation is observed

Question 10

What are the characteristics (in terms of process) of semi-automated method?

Answer 10

1) Uses large cuvettes
2) Uses digital dry bath
3) Manual rgnt aspiration
4) Manual sx aspiration
5) Automated timer
6) Manual incubation
7) Manual or automated computation of INR
8) Uses a magnetic stir bar
9) Detects visible clot formation using optical sensors

Question 11

What are the characteristics (in terms of process) of automated method?

Answer 11

1) Uses small cuvettes
2) Uses rxn wells
3) Automated rgnt aspiration
4) Automated sx aspiration
5) Automated timer
6) Automated incubation
7) Automated computation of INR
8) Does not use a magnetic stir bar
9) Detects visible clot formation using optical or electromechanical sensors

Question 12

What are the characteristics (in terms of process) of POCT method?

Answer 12

1) Does not use small cuvettes
2) Does not use a H2O bath nor rxn wells
3) No rgnt aspiration
4) No sx aspiration
5) Automated timer
6) No incubation
7) Does not use a magnetic stir bar
8) Detects visible clot formation using electromechanical sensors
9) Recommended for bedside warfarin monitoring using capillary blood

Question 13

What are the diff results in secs (w/ corresponding interpretations) of PT?

Answer 13

1) < 12.6 secs: shortened
2) 12.6 - 14.6 secs: normal
3) > 14.6 secs: prolonged

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 14

What are the diff results in INR for pts not on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 14

1) < 0.8: decreased
2) 0.8 - 1.2: normal
3) > 1.2: increased

Question 15

What are the diff results in INR for pts on warfarin therapy (w/ corresponding interpretations) of PT?

Answer 15

1) < 2.0: insufficient warfarin dosage
2) 2.0 - 3.0: warfarin therapy successful
3) > 3.0: excess warfarin dosage or warfarin overdose