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HEMATOLOGY 2 :) > COAGULATION SYSTEM (PART II) > Flashcards

COAGULATION SYSTEM (PART II) Flashcards

1
Q

Hemostasis Specimen Collection

A

Blue-top or blue-stopper

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2
Q

Blue-top or blue-stopper buffered _____ (3.2%) sodium citrate

A

0.105 to 0.109 M

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3
Q

It reversibly binds calcium ions to prevent coagulation .

A

Sodium citrate

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4
Q

The specimen must be collected first or immediately after a

A

non-additive tube

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5
Q

Ratio of blood to anticoagulant

A

9:1 or
2.7 ml (blood) to 0.3 ml (anticoagulant)

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6
Q

IF patient’s hematocrit is 55%

A

C=(1.85x10^-3) (100-HCT) V

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7
Q

C in the formula is

A

sodium Citrate in milliliters

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8
Q

V is

A

Volume of whole blood-sodium citrate solution in milliliters

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9
Q

HCT

A

hematocrit in percent (%)

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10
Q

1.85 x 10-3 is

A

constant

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11
Q

EDTA should __ be used. EDTA____chelates calcium ions

A

Not, irreversibly

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12
Q

Specimen collection errors

A

Short draw
Specimen clot
Visible hemolysis
Lipemia or icterus
Tourniquet more than 1min
Specimen storage at 1-6c
Specimen storage at greater than 25C

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13
Q

Must be tested within 24 hours
of the time of collection

A

PT

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14
Q

Must be tested within 4 hours
of the time of collection

A

For APTT

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15
Q

Platelet Function Tests

A
  1. Bleeding Time Test
  2. Von Willebrand Factor Activity Assays
  3. Platelet Aggregometry
  4. Heparin-Induced Thrombocytopenia Assays
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16
Q

Was the original test of platelet function (now obsolete). First described by Duke. Modified by Ivy

A

Bleeding Time Test

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17
Q

BP cuff inflated at 40 mmHg; incisions made on the volar surface of the forearm; blotted
every 30 seconds)

A

Bleeding Time Test

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18
Q

Requires a panel of quantitative and functional assays and these include: VWF antigen (VWF:Ag) immunoassay, Clot-based coagulation factor VII assay, Functional VWF ristocetin cofactor assay (VWF:RCo),Dilute ristocetin-induced platelet aggregation assay
(RIPA)

A

Von Willebrand Factor Activity Assays

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19
Q

Von Willebrand Factor Activity Assays. Requires a panel of quantitative and functional assays and these include:

A

○ VWF antigen (VWF:Ag) immunoassay
○ Clot-based coagulation factor VII assay
○ Functional VWF ristocetin cofactor assay (VWF:RCo)
○ Dilute ristocetin-induced platelet aggregation assay (RIPA)

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20
Q

A. Platelet aggregometry with Platelet-Rich Plasma (PRP)
B. Whole blood platelet aggregometry
C. Platelet lumiaggregometry

A

Platelet Aggregometry

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21
Q

Clot-Based Screening Tests for Coagulation
Disorders

A
  1. Prothrombin time
  2. Partial Thromboplastin time
  3. PTT mixing studies
  4. Thrombin clotting time
  5. Venom Activated assays
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22
Q

Was the first laboratory procedure designed to assess coagulation

A

Lee-White Whole Blood Coagulation Time Test

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23
Q

Lee-White Whole Blood Coagulation Time Test principle?

A

The time interval from the initiation of clotting to visible clot formation reflects the condition of the coagulation mechanism

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24
Q

Lee-White Whole Blood Coagulation Time Test was modified to?

A

Activated Clotting Time (ACT) Test

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25
Uses a particular clot activator in the test tube, which speeds clotting process. Is still widely used as a POCT
Activated Clotting Time (ACT) Test
26
PT (Prothrombin Time) reagents:
tissue factor phospholipids 0.025 M solution of calcium chloride
27
Prothrombin time other terms?
Thromboplastin, tissue thromboplastin
28
In PT organic extracts of emulsified ra__ or __ suspended in calcium chloride
rabbit brain, lung
29
The clot is detectable by optical or electromechanical sensors
Prothrombin time
30
Prothrombin time is most sensitive to ?
Factor VII
31
PT is Insensitive to deficiencies of factors?
VIII, IX, XI, XII
32
Is used most often to monitor the effects of therapy with Coumadin
Prothrombin Time
33
PT Is typically reported as a combination of
PT (in seconds) and INR (as PT/INR)
34
NV of PT
12.6-14.6 seconds
35
INR meaning
International Normalized Ratio
36
Prolonged PT results in:
○ DIC ○ Liver disease ○ Vitamin K deficiency
37
Is particularly sensitive to liver disease
Prothrombin Time
38
PTT
Partial Thromboplastin Time
39
Is employed to monitor the effects of UFH and to detect LAC and specific coagulation factor antibodies (anti-factor VIII antibody)
Partial Thromboplastin time
40
Is prolonged in all congenital and acquired procoagulant deficiencies (except VII and XIII)
Partial Thromboplastin time
41
PTT reagent contains:
1.Phospholipid (previously called partial thromboplastin or cephalin) - historically extracted from rabbit brain. 2.Negatively charged particulate activator (kaolin, ellagic acid, silica, or celite)
42
NV of PTT:
26-38 seconds
43
PTT is prolonged when there is a deficiency of one or more of the following coagulation factors:
II, V, VIII, IX, X, XI, XII
44
PTT Most common deficiencies:
Factor VIII (Hemophilia A) Factor IX (Hemophilia B) Factor XI (Rosenthal syndrome)
45
Is not affected by factor VII and XIII deficiencies
Partial Thromboplastin time
46
Deficiencies of the contact factor complexes:
1.Prolonged PTT 2.Not associated with bleeding
47
prolonged in the presence of the following: ○ Specific inhibitor (anti-factor VIII) ○ Nonspecific inhibitor (LACs) ○ Interfering substances (fibrin degradation products, paraproteins)
Partial Thromboplastin time
47
Distinguish LACs from specific inhibitors and factor deficiencies
PTT mixing studies
48
In PTT mixing studies , If PTT is prolonged
a test for UFH using TCT (Thrombin Clotting Time) is done.
49
In PTT mixing studies, Increased TCT?
positive for UFH (Unfractionated Heparin)
50
Unfractionated Heparin UFP is neutralized with
polybrene or heparinase
51
UFH-free or UFH-neutralized patient plasma is mixed__ with reagent platelet-poor normal plasma (PNP)
(1:1)
52
A repeat __is performed immediately on the patient plasma-PNP mixture
PTT
53
PTT mixing studies, temperature-dependent
○ 15% LAC ○ 85% anti-factor VIII
54
If the immediate mix PTT corrects, a new ___
1:1 mixture is prepared and incubated 2 hours at 37C
55
In PTT Incubated mix fails to correct and presence of bleeding
LAC
56
In PTT Incubated mix fails to correct with NO bleeding
Anti-factor VIII
57
TCT (Thrombin Clotting time) reagent
bovine thrombin
58
reagent cleaves fibrinopeptides A and B from plasma fibrinogen to form a detectable fibrin polymer
Commercially prepared bovine thrombin
59
Is part of the PTT mixing studies
TCT
60
Is used to determine whether UFH is present whenever the PTT is prolonged
Thrombin clotting time
61
Typical reference range of TCT:
15-20 sec
62
TCT Prolonged when:
1. Fibrinogen is <100 mg/dL (hypofibrinogenemia) 2. Presence of antithrombotic materials (FDP, paraproteins, or UFH) 3. Dysfibrinogenemia & afibrinogenemia
63
Is not sensitive to factor XIII
Thrombin clotting time
64
May also assess the presence of the oral direct thrombin inhibitor dabigatran
TCT
65
Plasma-diluted TCT: provides quantitative measure of
dabigatran
66
a thrombin-like enzyme isolated from the venom of Bothrops atrox (lancehead viper)
Reptilase Time
67
Cleaves fibrinopeptide A only
Reptilase Time
68
The reagent is reconstituted with distilled water
Reptilase Time
69
Insensitive to UFH and FXIII deficiency but is markedly prolonged in dysfibrinogenemia
Reptilase Time
70
Useful for detecting hypofibrinogenemia or dysfibrinogenemia
Reptilase Time
71
Also prolonged in the presence of FDP and paraproteins
Reptilase Time
72
Russell Viper Venom (RVV) is from the?
Daboia russelii viper
73
RVV triggers coagulation at the level of ?
factor X
74
Was once used as an alternative to the PT
Russell Viper Venom Test
75
Russell Viper Venom Test also named as ?
Stypven Time (now obsolete)
76
Coagulation Factor Assays
1. Fibrinogen Assay 2. Single-Factor Assays using the PTT 3. Nijmegen-Bethesda Assay 4. Single-Factor Assays using the PT 5. Factor XIII Assay
77
● Clot-based method of Clauss: ○ A modification of TCT ○ Is the recommended procedure for estimating fibrinogen function
Fibrinogen Assay
78
Fibrinogen Assay reagent?
○ Owren buffer ○ Bovine thrombin
79
The interval to clot formation is ____ to the concentration of functional fibrinogen
inversely proportional
80
Factor VIII-depleted or –deficient PPP provides normal activity of all procoagulants except factor VIII
Single-Factor Assays using the PTT
81
● Factor VIII-depleted PPP (alone)
prolonged PTT, Single-Factor Assays using the PTT
82
Factor VIII-depleted PPP + Normal patient plasma:
PTT reverts to normal, Single-Factor Assays using the PTT
83
Factor VIII-depleted PPP + Factor VIII-deficient patient plasma:
prolonged
84
Confirms and quantifies anti-factor VIII inhibitor (typically IgG4-class immunoglobulin)
Nijmegen-Bethesda Assay
85
A refined procedure of Bethesda titer
Nijmegen-Bethesda Assay
86
Is expressed as a percentage of the control
Nijmegen-Bethesda Assay
87
The percentage of factor VIII activity neutralized is proportional to the level of inhibitor activity
Nijmegen-Bethesda Assay
88
Bethesda titer is affected by:
o Residual patient plasma coagulation factor o Dabigatran o UFH o Coexistence of LAC o Differences in inhibitor epitope specificity o Neutralizing versus nonneutralizing inhibitor kinetics
89
Single-Factor Assays using the PT The principles and procedures described in the section on single-factor assay using the PTT system may be applied except
that PT reagent replaces the PTT reagent in the test system, and the PT protocol is followed
90
In factor XIII deficiency, neither the PT nor the PTT is prolonged
Factor XIII Assay
91
Quantitation of factor XIII activity is based on the measurement of ammonia released during an in vitro transglutaminase reaction
Chromogenic factor XIII assay (Technochrom Factor XIII)

HEMATOLOGY 2 :) (5 decks)

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