Partial Thromboplastin Time (F)

Question 1

Partial thromboplastin time is also called as what?

Answer 1

Activated Partial Thromboplastin Time (APTT)

Question 2

What are the purposes of PTT?

Answer 2

1) Tests the efficiency of intrinsic and common pathways in vitro
2) Monitors the effects of unfractionated heparin therapy
3) Detects the presence of lupus anticoagulants and factor inhibitors

Question 3

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

Answer 3

1) PPP + activator (e.g. celite / silica) + phospholipid
2) Incubate
3) + Calcium
4) Record clotting time

Question 4

What is the composition of PTT rgnt?

Answer 4

Phospholipids + negatively charged particulate activators

Question 5

What are the characteristics of PTT rgnt?

Answer 5

1) There is a separate rgnt for calcium chloride

2) Often in liquid form

Question 6

Phospholipids are previously called as what?

Answer 6

Cephalin or partial thromboplastin

Question 7

What is the purpose of activator?

Answer 7

It substitutes for the collagen for intrinsic pathway in vivo

Question 8

What are the exs of negatively charged particulate activators?

Answer 8

1) Silica
2) Kaolin
3) Ellagic acid
4) Celite

Question 9

What are the characteristics of phospholipids?

Answer 9

Phospholipids could be:

1) Synthetic
2) Organic (emulsified rabbit brain)

Question 10

What are the diff methods for PTT?

Answer 10

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

Question 11

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

Answer 11

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

Question 12

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

Answer 12

1) Incubate the PTT rgnt and CaCl2 at 37 DC. No reconstitution is needed
2) Transfer 50 - 100 uL of citrated PPP into a tube / cuvette. Incubate this aliquot at 37 DC for 3 mins
3) Add 50 - 100 uL of warmed PTT rgnt directly to the warmed citrated PPP. Incubate this mixture at 37 DC for 3 mins
4) Add 50 - 100 uL of warmed CaCl2 rgnt directly to the mixture. Start timer. Record the time until visible clot formation is observed

Question 12

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

Answer 12

1) Incubate the PTT rgnt and CaCl2 at 37 DC. No reconstitution is needed
2) Transfer 50 - 100 uL of citrated PPP into a tube / cuvette. Incubate this aliquot at 37 DC for 3 mins
3) Add 50 - 100 uL of warmed PTT rgnt directly to the warmed citrated PPP. Incubate this mixture at 37 DC for 3 mins
4) Add 50 - 100 uL of warmed CaCl2 rgnt directly to the mixture. Start timer. Record the time until visible clot formation is observed

Question 12

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

Answer 12

1) Incubate the PTT rgnt and CaCl2 at 37 DC. No reconstitution is needed
2) Transfer 50 - 100 uL of citrated PPP into a tube / cuvette. Incubate this aliquot at 37 DC for 3 mins
3) Add 50 - 100 uL of warmed PTT rgnt directly to the warmed citrated PPP. Incubate this mixture at 37 DC for 3 mins
4) Add 50 - 100 uL of warmed CaCl2 rgnt directly to the mixture. Start timer. Record the time until visible clot formation is observed

Question 13

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

Answer 13

1) Incubate the PTT rgnt and CaCl2 at 37 DC. No reconstitution is needed
2) Transfer 50 - 100 uL of citrated PPP into a tube / cuvette. Incubate this aliquot at 37 DC for 3 mins
3) Add 50 - 100 uL of warmed PTT rgnt directly to the warmed citrated PPP. Incubate this mixture at 37 DC for 3 mins
4) Add 50 - 100 uL of warmed CaCl2 rgnt directly to the mixture. Start timer. Record the time until visible clot formation is observed

Question 14

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

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

1) < 25 secs: shortened
2) 25 - 35 secs: normal
3) > 35 secs: prolonged

Question 17

What are the results for pts on heparin therapy (w/ corresponding interpretations) of PTT?

Answer 17

1) < 60 secs: insufficient heparin dosage
2) 60 - 100 secs: heparin therapy successful
3) > 100 secs: excess heparin dosage or heparin overdose