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coag pt.1 Flashcards

1
Q

Who described a procedure called Prothrombin Time (PT) Test in the mid-1930s?

A

Dr. Armand Quick

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2
Q

HISTORY:
DATE - PERSON/S - CONTRIBUTION

A

1905 - Paul Morawitz - comprehensive explanation of theory of coagulation

1913 - Dr. Roger Lee and Paul White - Lee and White Whole Blood Clotting Time

1930s - Dr. Armand Quick - Prothrombin Time

1950s - Blood from hemophiliacs (Normal PT, Inability to clot) - Partial Thromboplastin Time

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3
Q

What is Prothrombin Time (PT) Test used for?

A

Evaluating the Extrinsic Coagulation System

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4
Q

What test was developed in the 1950s as a result of studying blood from hemophiliacs?

A

Partial Thromboplastin Time (PTT) test

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5
Q

CAPILLARY BLOOD METHODS: Intrinsic and Common Pathway and Optimal Coagulation time (Reference Range)

A
  1. Slide Method (2-6 minutes)
  2. Capillary Tube Method (2-6 minutes)
  3. Dale and Laidlaw Method (1-3)
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6
Q

Explain the process of Dale and Laidlaw Method

A
  1. finger puncture
  2. record time
  3. allow blood to flow into capillary tube with lead bead
  4. incubate (water bath) @ 37C
  5. tilt tube until bead adhere to fibrin clot
  6. record time (stop time)
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7
Q

Outcome/ Result of Dale and Laidlaw Method

A

Fibrin threads

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8
Q

VENOUS BLOOD METHODS: Intrinsic and Common Pathway and Optimal Coagulation time (Reference Range)

A
  1. Lee and White Coagulation Metho (5-15 mins)
  2. Howell’s Method (10-30 mins)
  3. Silicone Tube Method (20-60 min)
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9
Q

Explain the process of Howell’s Method

A
  1. syringe coated with petrolatum
  2. blood collection
  3. transfer to tubes
  4. tilt til coagulation is observed
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10
Q

Explain the process of Silicone tube method

A
  1. Syringe coated with silicone
  2. blood collection
  3. blood transferred to 2 tubes coated with silicone
  4. incubate (water bath) @ 37C
  5. Tilt til coagulation is observed
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11
Q

purpose of silicone in Silicone Tube Method

A

to decrease contact of blood to glass surfaces

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12
Q

Result/Outcome of Venous Blood Methods

A

solid clot

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13
Q

SOURCES OF ERROR: Coagulation is Hastened

A
  1. dirty glassware
  2. tissue fluid in blood [swimming w/ same needle ; squeezing/milking]
  3. air bubbles [faulty venipuncture ; needle not properly positioned in vein]
  4. excessive agitation of blood
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14
Q

SOURCES OF ERROR: Coagulation is delayed

A
  1. Temp < 35C (95F)
  2. Temp > 45C (113F)
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15
Q

What is the basis of the test, Plasma Recalcification Time?

A

Except for calcium, normal PRP contains all components necessary for clotting

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16
Q

Modification of LWCT

A

Plasma Recalcification Test

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17
Q

Plasma Recalcification Test: Samples used

A

citrated plasma, CaCl2 (Calcium Chloride), Glass/ siliconized tubes with PRP or PPP or both

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18
Q

Why is the removal of red cells important?

A

Makes the clot easier to see

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19
Q

What does the clotting time of Plasma Recalcification test measure?

[Time required to form clot after addition of Calcium]

A

Intrinsic and common pathways

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20
Q

What are the reference ranges for PRP and PPP in a Plasma recalcification test?

A

PRP 100-150 sec, PPP 130-240 sec

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21
Q

What is the expected clotting time difference between PRP and PPP?

A

PRP should clot 20 sec faster

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22
Q

What are the principal disadvantages Plasma Recalcification Test?

A
  1. Difficulty in standardizing platelet number,
  2. Lengthy test time,
  3. Errors in collection technique affect results [amount of glass contact]
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23
Q

What should be done with the size of tubes for testing for standardization?

A

Use the same size

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24
Q

How to improve the sensitivity of Plasma Retraction Test

A

Dilute plasma

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25
Q

Plasma Recalcification Test: What are the three things accomplished by diluting plasma?

A
  1. Adjusts PRP closer to actual in vivo platelet count,
  2. increases test sensitivity to factor deficiencies,
  3. dilutes natural inhibitors to coagulation present in the sample
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26
Q

What should be done with a normal control for each test?

A

Run normal control with each test

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27
Q

What does a prolonged APTT indicate in the absence of heparin use?

A

Factor deficiency, acquired circulating anticoagulant, antibody to a specific factor

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28
Q

What are the sources of error in coagulation tests?

A

Sample collection, reagent preparation, instrumentation

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29
Q

Why should anticoagulant volume be adjusted for individuals with specific hematocrit levels?

A

To avoid error from incorrect anticoagulant-to-plasma ratio

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30
Q

What may cause a falsely shortened APTT?

A

Hemolysis or platelets in the sample

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31
Q

What can spuriously lengthen the APTT?

A

Unexpected heparin contamination

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32
Q

What factors may affect reagents in APTT testing?

A

Improper storage, water impurities, incorrect dilution

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33
Q

Who described PT as one stage PT

A

Dr. Armand quick

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34
Q

Indirect measurement of prothrombin of plasma dependent on presence of fibrinogen

A

PT

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35
Q

factors that can be screened by using PT

A

1 2 5 7 10

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36
Q

Prothrombin factors

A

2 7 9 10

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37
Q

What anticoagulant therapy is PT used for

A

Vit K antagonist therapy

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38
Q

How does Russell’s viper venom affect the clotting cascade?

A

Bypasses Factor VII and activates Factor X

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39
Q

viper venom is obtained from

A

viper russell

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40
Q

Tests to determine efficiency of Extrinsic pathway

A
  1. PT
  2. Stypven (russell’s viper venom test)
  3. prothrombin-proconvertin ratio
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41
Q

What is the purpose of the prothrombin-proconvertin time (P&P) test?

A

Detect deficiencies in extrinsic and common pathways

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42
Q

What is the significance of an abnormal PT and Russell’s viper venom time?

A

Deficiency or presence of Factor X friuli

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43
Q

developed by drs. owren ans aas

A

p & p test

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44
Q

P & P test: Specimen

A

Plasma diluted @ 1:10 with dilute thromboplastin from bovine brain, CaCl, excess bovine factor 1 and 5

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45
Q

What is the difference between the original P&P test and the Thrombotest?

A

Thrombotest uses a freeze-dried reagent

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46
Q

What is Thrombotest commonly used for in the Netherlands and Scandinavia?

A

Monitoring vit.K antagonist therapy

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47
Q

Why was Thrombotest particularly favored in the U.S. at one time?

A

Sodium oxalate failed to hold factor V stable

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48
Q

What has the development of monoclonal antibodies provided for immunologic testing?

A

Highly specific antisera

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49
Q

What have synthetic substrates enabled in the study of coagulation?

A

Viewing coagulation from an enzymatic perspective

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50
Q

What endpoint do methodologies in coagulation testing depend on?

A

Detection of a fibrin clot

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51
Q

What are the common methods for clot detection?

A

Manual tilt-tube, electromechanical (fibrin strand), optical density (turbidity)

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52
Q

Which clot detection method potentially offers more reproducible results?

A

Optical density (turbidity) methods

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53
Q

What are B immunologic methods gaining importance for?

A

Hereditary variants of coagulation proteins

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54
Q

What is a protein termed when it has normal antigenic properties but lacks functional activity?

A

Cross reactive material (CRM)

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55
Q

What is plasma containing a protein lacking functional activity called?

A

CRM+

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56
Q

What is the reason for the blood clots faster in a test tube with a small diameter?

A

the amount of foreign surface area (glass) to the amount of a blood is increased

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57
Q

The Coagulation Time is mainly used in the diagnosis and treatment of what?

A

hemorrhagic diseases [Abnormal bleeding]

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58
Q

Coagulation time can be used before surgical operations. T or F

A

TRUE

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59
Q

Discuss the relationship of Coagulation (clot formation) and Coagulation time (time it takes for clot to form)

A

? Coagulation = ? Coagulation Time [Hastened clot formation decreases time for clot to appear]
? Coagulation = ? Coagulation Time [Delayed clot formation increases time for clot to appear]

Therefore, Inversely proportional

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60
Q

What temperature does diatomaceous earth require blood to be kept warmed to?

A

37?C

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61
Q

What does diatomite act as in ACT?

A

Activator for contact factors

62
Q

What are the contact factors

A

Factor 11, Factor 12, PK, HMWK

63
Q

What temperature is the blood temperature constant?

A

37?C

64
Q

How much diatomite is needed in each of the 2 evacuated tubes?

A

12 mg

65
Q

what special incubator is used for warming?

A

portable heat block

66
Q

When blood begins to flow into the tube, what is started?

A

the first stopwatch

67
Q

clot is check at what intervals in ACT

A

tilting it at 5-sec intervals

68
Q

ACTIVATED CLOTTING TIME: Principle

A

WB contains all components to form clot, when removed from veins and put into a glass tube. By addition of an activator and warming, a reliable and rapid screen for intrinsic and common pathway is obtained

69
Q

ACTIVATED CLOTTING TIME: Reagent

A

2 Evacuated Tubes with 12 mg diatomite

70
Q

ACTIVATED CLOTTING TIME: Equipment

A

Portable heat block, thermometer, stopwatch

71
Q

ACTIVATED CLOTTING TIME: Procedure

A
  1. Evacuated tubes are prewarmed @ 37C in heat block
  2. 2ml of blood is obtained
  3. Tourniquet is removed, and first tube is inserted in needle
  4. 1st stopwatch is started at first contact of blood with tube.
  5. Tube is filled and placed in the heat block
  6. 2nd tube inserted in needle
  7. 2nd stopwatch is started at first contact of blood with tube. Tube filled and placed in heat block.
  8. After 60s, 1st/2nd tube is tilted @ 5 SEC INTERVALS until clot is formed
  9. stopwatch is stopped at first sight of clot.
72
Q

ACTIVATED CLOTTING TIME: Reference Range

A

Normal: 75 - 120 secs
Heparin Therapy: 140 - 185 secs

73
Q

Duplicates (Difference if T1 and T2) in ACT should agree at how many seconds?

A

10 secs

74
Q

What is the target range during heparin therapy?

A

140 to 185 seconds

75
Q

ACTIVATED CLOTTING TIME: Interpretation

Prolonged ACT

A
  1. one or more factor defects in the intrinsic/ common pathway
  2. presence of circulating anticoagulant [Heparin (due to heparin therapy)}
76
Q

How was PTT refined

A

addition of negative charged particles

77
Q

modification of PTT

A

APTT

78
Q

APTT/ PTT is the Test of choice for (3)?

A
  1. factor deficiencies in the intrinsic and common pathways
  2. heparin monitoring
79
Q

APTT reagent consists of two components

A
  1. platelet substitute (Phospholipids)
  2. Activators
80
Q

Source of phospholipids

A

brain/plant phospholipids

81
Q

Activators in APTT/PTT

A

Kaolin, Celite, Ellagic acid, micronized silica

82
Q

What type of acid is used as the activator?

A

ellagic acid

83
Q

APTT/PTT: Principle

A

APTT measure all factors except 7 and 8. Maximum activation of contact factors is achieved by addition of activator. Phospholipids are used to substitute/replace factor 3

84
Q

APTT/PTT: Reagents

A

Phospholipid + Activator (APTT reagent)
0.025M CaCl2

85
Q

APTT/PTT: Control

A

Commercial lyophilized control

86
Q

APTT/PTT: Procedure

A
  1. 0.1 ml of PPP to 0.1 ml APTT
  2. Incubate @ 37C in heat block for 3-5 mins
  3. to warmed soln, add 0.1ml CaCl
  4. Record time of clotting
87
Q

APTT/PTT: Reporting

A

report in seconds to the nearest tenth

88
Q

APTT/PTT: Reference range

A

20-45 secs

89
Q

APTT/PTT: Interpretation

Prolonged APTT

A
  1. deficient of factors in intrinsic and common
  2. presence of circulating anticoagulant (lupus inhibitor)
  3. antibody specific factor (factor 8 )
90
Q

What factors does the APTT not measure?

A

VII and XIII

91
Q

What adds the maximum activation of contact factors?

A

activator

92
Q

What is supplied to substitute for platelet Factor 3?

A

Phospholipid

93
Q

What type of plasma should be collected?

A

Citrated platelet-poor plasma

94
Q

What is the concentration of Ca chloride ?

A

0.025M

95
Q

What is recommended to be used?

A

a normal control and at least one abnormal control

96
Q

At what temperature is APTT reagent incubated?

A

37?C

97
Q

How much warmed Ca chloride is added after incubation?

A

0.1ml

98
Q

What happens after incubation?

A

clotting

99
Q

What is the lower limit of reference ranges?

A

20 sec

100
Q

How long can the reference ranges extend from a lower limit of 20 sec. to an upper limit of what?

A

45 sec

101
Q

What does calcium react with to convert Factor X to Xa?

A

factor VIIa and IIIa

102
Q

What does Xa with Va +phospholipid & Ca2+ convert to?

A

thrombin (Factor IIa)

103
Q

Besides Factor Xa, phospholipid & Ca2+ what else can convert prothrombin to thrombin?

A

Factor Va

104
Q

PT: Principle

A

3a + 7a + Ca
10 = 10a
10a + 5a + Ca+ phospholipids
2 = 2a
2a
1 = 1a
1a + 8a
stable fibrin clot

105
Q

PT: Specimen

A

Citrated PPP

106
Q

What is the reagent added to record the time from the addition of to the formation of a clot?

A

thromboplastin/CaCl2

107
Q

What is the PT reagent?

A

Thromboplastin/CaCl2

108
Q

How cool is the PT thromboplastin reagent?

A

37?C

109
Q

PT: Procedure

A
  1. warmed control and patient plasma
  2. PT reagent in water bath @ 37C (3-5mins)
  3. plasma in water bath @ 37C for 3-5 mins
  4. 0.2ml PT reagent + 0.1ml plasma [while still in water]
  5. record clotting time
110
Q

How long does it take to warm the PT thromboplastin reagent?

A

3 to 5 minutes

111
Q

How much plasma does PT reagent contain?

A

0.1ml plasma

112
Q

What amount of PT reagent is added to plasma?

A

0.2ml

113
Q

What are the normal values of REFERENCE RANGE?

A

10-12 secs/ 12-14 secs

114
Q

In some photo-optical systems, what are the values of manual methods?

A

12-14 sec

115
Q

PT: Reporting

A
  1. px time (in secs) with reference range
  2. px time (in secs) with control
  3. Prothrombin Ratio
  4. % Activity
  5. International Normalized Ratio (INR)
116
Q

What is the name of the standardized prothrombin times?

A

INR

117
Q

What is the ISI of a standard reagent?

A

1

118
Q

What is the INR most applicable in?

A

standardizing anticoagulant intensity

119
Q

PT: Reporting Equations

A

PT Ratio = (PT of px / mean of reference range)(100)

% Activity = (control/ px PT) (100)

INR = (px PT/control) (ISI)

120
Q

Conditions with recommended INR of 2.0-3.0

A
  1. prevention and treatment of venous thrombosis
  2. Acute MI
  3. stroke
  4. pulmonary embolism
121
Q

Conditions associated with prolonged PT

A
  1. Vit k deficiency
  2. Coagulopathy with liver disease
  3. warfarin therapy
  4. lupus anticoagulants
  5. hyperfibrinogenemia/ Dysfibrinogenemia
  6. deficiency in individual clotting factors
  7. Abs to bovine factor 5
122
Q

The P and p test has little value to the extrinsic systemas an overall screen because of its insensitivity to what?

A

factor V & fibrinogen

123
Q

What is the anticoagulant of choice?

A

sodium citrate

124
Q

What does the substrate have?

A

specificity

125
Q

What allows coagulation testing to be approached as a series of enzymatic reactions in an accurate and sensitive manner?

A

Synthetic substrate assays

126
Q

What is necessary for optimal use of synthetic substrate assays?

A

Knowledge of enzyme kinetics

127
Q

Many assays have been adapted for use on what?

A

automated instrumentation

128
Q

What can be performed?

A

Endpoint or initial rate analysis

129
Q

What is the first method to measure the prothrombin concentration in?

A

plasma

130
Q

What is used to defibrinate test plasma?

A

thrombin

131
Q

What is the result of the addition of thrombin?

A

defibrinated

132
Q

What are the sources of factors V,VII, and X that convert all prothrombin to thrombin?

A

thromboplastin, calcium, and a source of factors V,VII, and X

133
Q

How is the thrombin formed measured?

A

aliquots

134
Q

What are the results expressed in?

A

prothrombin units/ml of plasma

135
Q

What type of plasma are the results expressed in?

A

prothrombin units/ml

136
Q

How long has a prothrombin time study been allowed to clot?

A

60 min

137
Q

What can slow the rate of prothrombin conversion?

A

platelet deficiencies or abnormalities

138
Q

How long will the prothrombin consumption time be?

A

short

139
Q

What will have a long time?

A

a normal serum

140
Q

How long will a normal serum have?

A

20-25 secs

141
Q

What will adsorb to certain coagulation factors?

A

barium sulfate or aluminum hydroxide

142
Q

What do barium sulfate and aluminum hydroxide adsorb to?

A

coagulation factors

143
Q

What can be done to remove factors II, VII, IX, and X?

A

centrifugation

144
Q

If blood is allowed to clot, the remaining serum will not contain fibrinogen, factor II, the labile factors V & VIII

A

XIII

145
Q

If blood is allowed to clot, the remaining serum will not contain what?

A

fibrinogen

146
Q

What is the name of the clot that cannot form a clot?

A

prothrombin

147
Q

What are the TGT reagents sometimes referred to as?

A

mixing studies or substitution studies

148
Q

What are assumed to be normal if the patient has a PT & prolonged APTT?

A

Factors I, II, V, VII & X

149
Q

What is corrected by addition of normal adsorbed plasma?

A

APTT

150
Q

What is corrected by normal serum with factors IV, VII, IX, X, XI, & XII?

A

APTT

Hema (3 decks)

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