8-SECONDARY HOMEOSTASIS PART 1 Flashcards
(261 cards)
1
Q
What must patients avoid prior to coagulation testing due to its anti-platelet effect
A
Caffeine
2
Q
What must patients avoid for 2 hours before coagulation testing to prevent activation of coagulation proteins
A
Exercise
3
Q
What must patients avoid for 30 minutes before coagulation testing due to elevated fibrinogen levels
A
Smoking
4
Q
How long should patients rest before coagulation blood collection to stabilize results
A
5 minutes
5
Q
What gauge needle is recommended for adults with good veins during coagulation blood collection
A
20 or 21 gauge thin-walled needle
6
Q
What gauge needle is used for children or adults with small fragile veins during coagulation blood collection
A
23-gauge Luer-adapter or winged-needle set
7
Q
What gauge transfer unit is recommended for transferring blood from syringe to tube to prevent hemolysis
A
19-gauge safety transfer unit
8
Q
What type of collection tubes are used for coagulation testing to prevent platelet activation
A
Plastic blue-closure evacuated tubes
9
Q
Why are silicone-coated glass tubes recommended for coagulation testing
A
Prevent contact activation of platelets + coagulation factors
10
Q
Why are uncoated soda-lime glass tubes unsuitable for coagulation testing
A
Activate contact factors leading to falsely-shortened results
11
Q
Which coagulation factors are activated by contact with glass surfaces
A
Prekallikrein + Factor XI + Factor XII
12
Q
What effect does caffeine coupled with exercise have on coagulation factors
A
Increased production
13
Q
What effect does smoking have on fibrinogen levels and prothrombin time
A
Elevated fibrinogen + Shortened prothrombin time
14
Q
What is the primary reason for using larger gauge needles in coagulation blood collection
A
Prevent hemolysis in samples
15
Q
What is the consequence of premature activation of contact factors in coagulation tests
A
Falsely-shortened clotting times
16
Q
What is the anticoagulant of choice for coagulation testing
A
Buffered sodium citrate 3.2 percent
17
Q
What is the volume of anticoagulant and whole blood in a 3 milliliter light blue top tube
A
0.3 milliliter anticoagulant + 2.7 milliliters whole blood
18
Q
What is the anticoagulant to whole blood ratio in light blue top tubes
A
1 part anticoagulant to 9 parts whole blood
19
Q
What is the volume of anticoagulant and whole blood in a 2 milliliter light blue top tube
A
0.2 milliliter anticoagulant + 1.8 milliliters whole blood
20
Q
What is the mechanism of action of sodium citrate as an anticoagulant
A
Binds calcium to prevent coagulation
21
Q
Why is sodium citrate buffered in coagulation tubes
A
To stabilize pH and increase stability of labile clotting factors
22
Q
What is the effect of uncapped tubes on sample pH
A
Loss of carbon dioxide increases pH causing deterioration of factors VIII and V
23
Q
Which coagulation factors are labile and affected by pH changes
A
Factors VIII and V
24
Q
What are features of buffered sodium citrate anticoagulant
A
Preserves labile factors + Suitable for platelet aggregation studies + Sensitive to heparin effects
25
Why is sodium citrate preferred over sodium oxalate
Sodium oxalate forms insoluble precipitates interfering with photometric assays
26
What is the required adjustment for sodium citrate volume in patients with hematocrit above 55 percent
Decrease anticoagulant volume using formula
27
What is the formula for citrate volume adjustment based on hematocrit
C equals 1.85 times 10 to the negative 3 times (100 minus hematocrit) times total volume
28
What is the consequence of increased hematocrit on plasma volume and anticoagulant concentration
Increased hematocrit decreases plasma volume and increases anticoagulant to plasma ratio
29
What gauge needle is preferred for adult coagulation blood collection
20 or 21 gauge thin-walled needle
30
What gauge needle is preferred for children or adults with fragile veins
23 gauge Luer-adapter or winged needle set
31
What gauge transfer device is recommended to prevent hemolysis during blood transfer
19 gauge safety transfer unit
32
Why are plastic blue-top tubes preferred for coagulation testing
Smooth surface prevents premature platelet activation
33
Why are silicone-coated glass tubes recommended
Prevent contact activation of platelets and contact factors
34
What is the effect of uncoated soda-lime glass tubes on coagulation testing
Premature activation of contact factors causing falsely shortened clotting times
35
What is the recommended order of draw when collecting coagulation samples
Blood culture tube first
36
What is the maximum time a tourniquet should be applied during venipuncture
One minute
37
What should be done if a winged blood collection set is used for coagulation sample collection
Draw a discard tube first to fill tubing dead space
38
What is the required blood to anticoagulant ratio in coagulation tubes
Nine parts blood to one part anticoagulant
39
What is the effect of underfilled coagulation tubes
Increased anticoagulant to blood ratio causing prolonged clotting times
40
What is the anticoagulant of choice for coagulation testing
Buffered sodium citrate three point two percent
41
What is the anticoagulant to whole blood ratio in a three milliliter light blue top tube
One part anticoagulant to nine parts whole blood
42
What is the required volume of anticoagulant in a three milliliter light blue top tube
Zero point three milliliter
43
What is the required volume of whole blood in a three milliliter light blue top tube
Two point seven milliliters
44
What is the required volume of anticoagulant in a two milliliter light blue top tube
Zero point two milliliter
45
What is the required volume of whole blood in a two milliliter light blue top tube
One point eight milliliters
46
What is the mechanism of action of sodium citrate
Binds calcium to prevent coagulation
47
What is the purpose of buffering sodium citrate
Stabilizes pH and increases stability of labile clotting factors
48
What is the effect of uncapped tubes on sample pH
Loss of carbon dioxide increases pH and deteriorates factors eight and five
49
What clotting factors are labile and affected by pH changes
Factor eight and factor five
50
What is the effect of sodium oxalate as an anticoagulant
Forms insoluble precipitates interfering with photometric assays
51
What is the adjustment needed for sodium citrate volume in hematocrit above fifty five percent
Decrease anticoagulant volume using formula
52
What is the formula for citrate volume adjustment based on hematocrit
C equals one point eight five times ten to the negative three times one hundred minus hematocrit times total volume
53
What is the effect of increased hematocrit on plasma volume and anticoagulant concentration
Increased hematocrit decreases plasma volume and increases anticoagulant to plasma ratio
54
What is the effect of excess anticoagulant in high hematocrit samples
Prolonged clot based coagulation results
55
What is the effect of excess anticoagulant chelating more calcium than necessary
Falsely prolonged clot based test results
56
What is the effect of excess calcium in low hematocrit or overfilled tubes
Falsely shortened clot based test results
57
What is the effect of traumatic collection on coagulation tests
Premature activation of extrinsic pathway and falsely shortened clot based results
58
What is the effect of a short draw on coagulation tests
Excess anticoagulant leads to prolonged clot based results
59
What is the effect of specimen clot on coagulation tests
Small clots interfere with results for prothrombin time and activated partial thromboplastin time
60
What is the effect of hemolysis on coagulation tests
Premature activation of platelets and falsely shortened prothrombin time and activated partial thromboplastin time
61
What is the effect of lipemic or icteric sample on coagulation tests
Optical instruments fail to measure clots and affect prothrombin time and activated partial thromboplastin time
62
What is the effect of tourniquet application longer than one minute on coagulation tests
Increased coagulation factors and falsely shortened clot based results
63
What is the effect of excessive agitation or cocktail shaking on coagulation tests
Hemolysis and falsely shortened clot based results
64
What is the effect of ethylenediaminetetraacetic acid as an anticoagulant for coagulation testing
Irreversibly chelates calcium and inhibits fibrinogen thrombin reaction causing prolonged clot based results
65
What is the effect of ethylenediaminetetraacetic acid on factor five
Factor five becomes unstable and deteriorates
66
What is the effect of heparin as an anticoagulant for coagulation testing
Inhibits all stages of coagulation and is not used for coagulation testing
67
What is the mechanism of action of heparin
Acts with antithrombin three to inhibit all stages of coagulation
68
What is the use of heparin as an anticoagulant in platelet studies
Used for platelet retention test because platelet adhesiveness is not affected
69
What interferes with hemostasis results causing prolonged prothrombin time and activated partial thromboplastin time
Small clots in specimen
70
Why are prothrombin time and activated partial thromboplastin time falsely prolonged with microclots
Pre-consumption of coagulation proteins before testing
71
What causes pre-consumption of coagulation proteins in a specimen
Clot formation before testing
72
What is the appearance of plasma in hemolysis
Pink or red plasma
73
How do hemolyzed red blood cells affect coagulation tests
Act like tissue thromboplastin activating clotting factors causing shortened prothrombin time and activated partial thromboplastin time
74
What substance released from ruptured red blood cells activates platelets prematurely
Adenosine diphosphate
75
Why are hemolyzed samples prohibited in coagulation testing
Premature activation of clotting factors causes falsely shortened clotting times
76
What effect do lipemic or icteric samples have on optical coagulation instruments
Mask clot detection causing falsely prolonged prothrombin time and activated partial thromboplastin time
77
What happens if tourniquet application exceeds one minute during blood collection
Blood stasis causes hemoconcentration increasing coagulation factors and shortening clotting times
78
Which coagulation factors increase due to hemoconcentration from prolonged tourniquet use
Factors five seven eight twelve and von Willebrand factor
79
What is the effect of excessive agitation or cocktail shaking on coagulation samples
Causes hemolysis and falsely shortened clotting times
80
What is the recommended storage temperature for coagulation specimens
Ambient temperature not refrigerated or on ice
81
Within how many hours must prothrombin time specimens be tested after collection
Within twenty-four hours
82
Within how many hours must activated partial thromboplastin time specimens be tested after collection
Within four hours
83
What must be maintained on blood collection tubes to preserve specimen integrity
Tube seal
84
What is the stability period for platelets after blood collection
Between thirty minutes and three hours
85
What is the recommended temperature for prothrombin time testing without unfractionated heparin
Fifteen to twenty-five degrees Celsius
86
What is the specimen stability time for prothrombin time without unfractionated heparin
Test within twenty-four hours
87
What is the specimen stability time for activated partial thromboplastin time without unfractionated heparin
Test within four hours
88
What is the specimen handling requirement for activated partial thromboplastin time when monitoring unfractionated heparin
Centrifuge to separate plasma within one hour
89
What is the specimen handling requirement for prothrombin time when unfractionated heparin is present
Centrifuge to separate plasma within one hour
90
What is the specimen stability time for factor assays
Test within four hours
91
What is the specimen stability time for optical platelet aggregometry using platelet rich plasma
Wait thirty minutes after centrifugation
92
What is the specimen stability time for whole blood aggregometry
Test within four hours of collection
93
What is the stability of specimens stored in household freezer at minus twenty degrees Celsius
Two weeks
94
What is the stability of specimens stored at minus seventy degrees Celsius
Six months or indefinite
95
What happens if specimens are stored at refrigerator temperature one to six degrees Celsius
Precipitation of von Willebrand factor
96
What is the effect of storing specimens above twenty-five degrees Celsius
Deterioration of factor five and seven
97
What is the effect of uncapped specimens
Loss of carbon dioxide
98
What is the effect of prolonged standing of sample at room temperature
Deterioration of labile coagulation factors
99
What is the effect of slow freezing of specimens
Formation of ice particles denaturing clotting proteins
100
What platelet count defines platelet poor plasma for clot-based coagulation tests
Less than ten thousand per microliter
101
What centrifugation conditions produce platelet poor plasma
Horizontal-head centrifuge at fifteen hundred times gravity relative centrifugal force for fifteen minutes
102
What is the effect of platelet counts greater than ten thousand per microliter in plasma
Platelet activation releasing microparticles and phosphatidylserine
103
What do platelets secrete that neutralizes heparin
Platelet factor four
104
What is the consequence of platelet factor four neutralizing heparin
Continuous coagulation protein activity
105
What was the first laboratory procedure designed to assess coagulation
Lee-White whole-blood coagulation time test
106
What does an increased clotting time indicate
Coagulopathy or coagulation factor deficiency
107
What pathways did the Lee-White test historically measure
Intrinsic and common coagulation pathways
108
What therapy was historically monitored by the Lee-White test
Heparin therapy
109
What are limitations of the Lee-White test
Time-consuming + Poor reproducibility + Sensitive only to extreme factor deficiencies + Insensitive to high doses of heparin
110
What is the principle of the Lee-White coagulation time test
Time interval from clotting initiation to visible clot formation
111
What equipment is required for the Lee-White test
Water bath at 37 degrees Celsius + Glass test tubes + Stopwatch + Plastic syringe + Twenty-gauge needle
112
What specimen is used for the Lee-White test
Fresh whole blood four milliliters
113
How many test tubes are labeled for the Lee-White test
Three tubes numbered one to three
114
What volume of blood is placed in each test tube in the Lee-White test
One milliliter per tube
115
Which test tube’s clotting time is reported in the Lee-White test
Tube number three because it contains the most recently collected blood
116
At what temperature are the test tubes incubated in the Lee-White test
Thirty-seven degrees Celsius
117
How often are test tubes tilted during the Lee-White test to check for clotting
Every thirty seconds after five minutes incubation
118
What is the normal range of clotting time in the Lee-White test
Seven to fifteen minutes
119
What is the principle of the slide or drop method of clotting time
Observation of fibrin strand formation in capillary blood
120
What specimen is used in the slide or drop method
Capillary blood
121
How is clotting time measured in the slide method
Timer started at second drop of blood and stopped when fibrin strands cling to needle tip
122
What is wiped off before starting the timer in the slide method of clotting time
First drop of blood
123
When is the timer started in the slide method of clotting time
At the appearance of the second drop of blood
124
Where is the second drop of blood placed in the slide method
Center of the glass slide
125
How often is the needle tip passed through the blood drop in the slide method
Every thirty seconds
126
What indicates the endpoint in the slide method of clotting time
Formation of fibrin strands clinging to the needle tip
127
What is the normal clotting time range in the slide method
Two to four minutes
128
What modification does the activated clotting time test have compared to Lee-White test
Uses particulate clot activator in test tube
129
What is the specimen used in activated clotting time test
Fresh whole blood
130
What temperature are tubes containing clot activator incubated at in activated clotting time test
Thirty-seven degrees Celsius
131
How many tubes with diatomite are used in activated clotting time test
Two tubes
132
What volume of blood is drawn and discarded before collecting sample in activated clotting time test
At least two milliliters
133
When is the stopwatch started during blood collection in activated clotting time test
When blood starts to flow into tube with diatomite
134
How often are tubes tilted to check clot formation in activated clotting time test
Every five seconds after sixty seconds incubation
135
What is the normal activated clotting time range
Seventy-five to one hundred twenty seconds
136
What is the activated clotting time range during heparin therapy
One hundred forty to one hundred eighty-five seconds
137
How is the final activated clotting time reported
Average of two duplicate tube clotting times
138
What is the common pathway assessed by Lee-White test
Intrinsic and common coagulation pathways
139
What is the common pathway assessed by slide or drop method
Intrinsic and common coagulation pathways
140
What is the common pathway assessed by activated clotting time test
Intrinsic and common coagulation pathways
141
What does the term partial mean in partial thromboplastin time
Reagent contains only phospholipid portion of tissue thromboplastin
142
What is the source of phospholipid in partial thromboplastin time reagent
Brain or plant phospholipids
143
What does the term activated mean in activated partial thromboplastin time
Addition of negatively charged activators
144
What are examples of negatively charged activators in activated partial thromboplastin time
Kaolin + Celite + Ellagic acid + Micronized silica
145
What is the plasma recalcification time a modification of
Lee-White whole blood coagulation time
146
What specimen is used in plasma recalcification time
Citrated plasma platelet poor plasma or platelet rich plasma
147
What reagent is used to recalcify the specimen in plasma recalcification time
Calcium chloride
148
What is the effect of increasing platelet count on plasma recalcification time
Shortened clotting time
149
What is the normal plasma recalcification time using platelet rich plasma
One hundred to one hundred fifty seconds
150
What is the normal plasma recalcification time using platelet poor plasma
One hundred thirty to two hundred forty seconds
151
What is the endpoint in plasma recalcification time
Clot formation after calcium chloride addition
152
What is the activated recalcification time a modification of
Plasma recalcification time
153
What activator is used in activated recalcification time
One percent celite
154
What is the normal activated recalcification time
Less than fifty seconds
155
What is the difference between plasma recalcification time and activated recalcification time
Presence of activator in activated recalcification time
156
What pathway is assessed by plasma recalcification time
Intrinsic and common pathways
157
What is the screening test for factor deficiencies in intrinsic and common pathways
Activated partial thromboplastin time
158
What test replaces the Lee-White whole blood coagulation time test
Activated partial thromboplastin time
159
What is the test of choice for detecting intrinsic and common pathway factor deficiencies
Activated partial thromboplastin time
160
What is activated partial thromboplastin time used to monitor
Heparin therapy
161
What factors do not prolong partial thromboplastin time when deficient
Factor seven and factor thirteen
162
What is the specimen for activated partial thromboplastin time
Platelet poor plasma
163
What anticoagulant binds calcium in whole blood to prevent coagulation prior to testing
Sodium citrate
164
Where does calcium come from in activated partial thromboplastin time testing
Reagent addition
165
What replaces platelets as phospholipid substitute in activated partial thromboplastin time reagent
Calcium and phospholipid
166
What is the specimen used in activated partial thromboplastin time
Citrated platelet poor plasma
167
What are the components of activated partial thromboplastin time reagent
Platelet substitute phospholipid + Negatively charged activators (kaolin
168
What is the source of calcium ions in activated partial thromboplastin time
Calcium chloride
169
What devices are used to measure clot formation in activated partial thromboplastin time
Electromechanical or photo-optical devices
170
What is the first step in activated partial thromboplastin time procedure
Mix equal volumes of prewarmed partial thromboplastin reagent and platelet poor plasma
171
How long is the mixture incubated in activated partial thromboplastin time test
Three minutes at thirty-seven degrees Celsius
172
What is added to the mixture after incubation in activated partial thromboplastin time
Calcium chloride
173
When is the timer started in activated partial thromboplastin time test
Immediately after adding calcium chloride
174
When is the timer stopped in activated partial thromboplastin time test
Upon clot formation
175
What is the normal reference interval for activated partial thromboplastin time
Twenty-five to thirty-five seconds
176
What coagulation factor deficiencies prolong activated partial thromboplastin time
Prothrombin + Factors five eight nine ten eleven twelve + Fibrinogen less than or equal to one hundred milligrams per deciliter
177
What specific inhibitors prolong activated partial thromboplastin time
Anti-factor eight + Anti-factor nine antibodies
178
What nonspecific inhibitor prolongs activated partial thromboplastin time
Lupus anticoagulant
179
What are examples of interfering substances prolonging activated partial thromboplastin time
Fibrin degradation products + Paraproteins
180
What is the effect of fibrin degradation products on coagulation
Inhibit platelet activation + Hinder fibrin polymerization causing bleeding and prolonged activated partial thromboplastin time
181
What is the effect of paraproteins on platelets
Coat platelets and diminish procoagulant activity causing prolonged activated partial thromboplastin time
182
What coagulation disorder causes prolonged activated partial thromboplastin time due to uncontrolled consumption
Disseminated intravascular coagulation
183
What vitamin K dependent factors affect activated partial thromboplastin time when deficient
Factors two seven nine ten
184
Why does vitamin K deficiency prolong activated partial thromboplastin time
Factors become nonfunctional and cannot bind calcium ions
185
What anticoagulant inhibits coagulation in all stages by acting with antithrombin three
Unfractionated heparin
186
What fragments are produced when free plasmin cleaves fibrinogen
Fragment X Fragment Y Fragment D Fragment E
187
What fragments are produced when bound plasmin cleaves fibrin
Fragment X Fragment Y Fragment D Fragment E D-dimer
188
What is D-dimer a specific product of
Cross-linked fibrin digestion only
189
What do fibrin degradation products prevent
Platelet activation and fibrin polymerization
190
What does D-dimer consist of
Two D domains from adjacent monomers
191
What pathway does activated partial thromboplastin time assess
Intrinsic and common pathways
192
What factors are assessed for deficiency by activated partial thromboplastin time
Factor one Factor two Factor five Factor eight Factor nine Factor ten Factor eleven Factor twelve
193
What factors cannot be detected as deficient by activated partial thromboplastin time
Factor seven Factor thirteen
194
What are contact activation factors in the intrinsic pathway
Factor twelve a Prekallikrein High molecular weight kininogen
195
What is the function of contact activation factors
Form complex and enhance activation in vitro
196
What pathway does prothrombin time assess
Extrinsic and common pathways
197
What therapy is monitored by prothrombin time
Coumadin therapy
198
What is prothrombin time most sensitive to
Factor seven deficiency
199
What is prothrombin time moderately sensitive to
Factor five and factor ten deficiency
200
What is prothrombin time sensitive to
Severe fibrinogen and prothrombin deficiency
201
What is prothrombin time insensitive to
Factor nine deficiency
202
What specimen is used for prothrombin time
Citrated platelet poor plasma
203
What reagent is used in prothrombin time
Thromboplastin or tissue thromboplastin with phospholipid and calcium chloride
204
What is the endpoint measured in prothrombin time test
Clot formation after addition of reagent
205
What is the effect of incubating prothrombin time reagents and specimen for longer than ten minutes
Deterioration of labile factors and falsely prolonged clotting time
206
What does prothrombin time assess deficiencies in
Factors one two five seven ten
207
What factor deficiencies cannot be detected by prothrombin time
Factors nine eight thirteen
208
What is the standardized way of reporting prothrombin time
International normalized ratio
209
Why was international normalized ratio introduced
To minimize differences in prothrombin time results due to different reagent-instrument combinations
210
What is the formula for calculating international normalized ratio
Patient prothrombin time divided by normal prothrombin time raised to international sensitivity index power
211
What international normalized ratio must be achieved for therapeutic anticoagulation
Two point zero to three point zero
212
What international normalized ratio is associated with increased risk of hemorrhage
Greater than five point zero
213
What is the normal reference interval for prothrombin time
Twelve point six to fourteen point six seconds
214
What causes prolonged prothrombin time in disseminated intravascular coagulation
Uncontrolled activation and consumption of coagulation factors
215
What causes prolonged prothrombin time in liver disease
Decreased synthesis of coagulation factors in hepatocytes
216
What sites besides liver synthesize coagulation factors
Monocytes + Megakaryocytes + Endothelial cells
217
What causes prolonged prothrombin time in vitamin K deficiency
Inability of vitamin K dependent factors to bind calcium
218
What congenital factor deficiencies prolong prothrombin time
Factor ten + Factor seven + Factor five + Prothrombin + Fibrinogen less than one hundred milligrams per deciliter
219
Why is prothrombin time not affected by factor eight or nine deficiency
Tissue factor-factor seven a complex bypasses these factors in vitro
220
What mnemonic helps remember that prothrombin time tests extrinsic pathway
Lawn Tennis is outdoor game like extrinsic pathway
221
What mnemonic helps remember that partial thromboplastin time tests intrinsic pathway
Table Tennis is indoor game like intrinsic pathway
222
How does tissue factor-factor seven a complex differ in vivo versus in vitro
Activates factor nine before factor ten in vivo + Directly activates factor ten in vitro
223
What clotting factor deficiency is assessed by thrombin clotting time
Factor one
224
What clotting factor deficiencies cannot be detected by thrombin clotting time
Other coagulation factors
225
What is the principle of thrombin clotting time
Addition of thrombin to plasma bypasses all coagulation reactions except fibrinogen polymerization
226
What does thrombin clotting time measure
Conversion of fibrinogen to fibrin
227
What reagent is used in thrombin clotting time
Commercially prepared bovine thrombin
228
What specimen is used in thrombin clotting time
Citrated platelet poor plasma
229
What is the normal reference interval for thrombin clotting time
Fifteen to twenty seconds
230
What does a prolonged thrombin clotting time indicate
Hypofibrinogenemia or presence of antithrombotic substances or afibrinogenemia or dysfibrinogenemia or presence of oral direct thrombin inhibitor
231
What substances can prolong thrombin clotting time
Fibrin degradation products + Paraproteins + Heparin
232
What is thrombin clotting time insensitive to
Factor thirteen deficiency
233
What is used to preserve thrombin reagent activity
Dilution with sodium chloride and glycerol then freezing
234
What happens to thrombin activity after twenty minutes at thirty-seven degrees Celsius
Decreases
235
What can be added to determine if heparin is the cause of prolonged thrombin clotting time
Protamine
236
What is the effect of protamine in thrombin clotting time
Neutralizes heparin and normalizes result
237
What is the endpoint of thrombin clotting time procedure
Fibrin clot formation
238
What type of pipet should be used for thrombin
Plastic or siliconized glass
239
What does thrombin remove from fibrinogen to form fibrin polymer
Fibrinopeptide A and fibrinopeptide B
240
What enhances the rate of fibrin monomer polymerization
Thrombin with calcium chloride
241
What pathway is assessed by partial thromboplastin time
Intrinsic and common
242
What pathway is assessed by prothrombin time
Extrinsic and common
243
What is the only factor assessed by thrombin time
Fibrinogen
244
What enzyme is reptilase and where is it isolated from
Thrombin-like enzyme batroxobin from Bothrops atrox venom
245
What fibrinopeptide does reptilase cleave
Fibrinopeptide A only
246
What fibrinopeptides does thrombin cleave
Fibrinopeptides A and B
247
What is reptilase insensitive to
Heparin and factor thirteen deficiency
248
What specimen is used in reptilase time test
Citrated platelet poor plasma
249
What is the normal reference interval for reptilase time
Eighteen to twenty seconds
250
What clinical conditions prolong reptilase time
Dysfibrinogenemia + Presence of fibrin degradation products + Presence of paraproteins
251
Why is platelet poor plasma required for reptilase time
To avoid nonspecific spontaneous platelet aggregation
252
What can eliminate thrombin interference in reptilase time
Heparin
253
What venom is used in Russell viper venom test
Russell viper venom from Daboia russelii
254
What coagulation factor does Russell viper venom activate
Factor ten in common pathway
255
What reagent is combined with Russell viper venom in testing
Dilute thromboplastin
256
What is the clinical use of Russell viper venom test
Screening for lupus anticoagulant and anti-phospholipid antibodies
257
What does prothrombin proconvertin time test detect
Minor coagulation factor deficiencies amplified by plasma dilution
258
What reagents are used in prothrombin proconvertin time test
Dilute thromboplastin extract bovine brain + Calcium chloride + Excess bovine factors five and one
259
What therapy prolongs prothrombin proconvertin time
Coumadin or Warfarin therapy
260
What is the specimen dilution in prothrombin proconvertin time test
One to ten dilution
261
What is the clinical value of prothrombin proconvertin time test
Limited clinical value
