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🩸Hema🎀 > 7: Laboratory Diagnosis of Coagulation > Flashcards

7: Laboratory Diagnosis of Coagulation Flashcards

1
Q

Was the first laboratory procedure designed to assess coagulation

A

Lee-White Whole Blood Coagulation Time Test

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2
Q

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

A

Lee-White Whole Blood Coagulation Time Test

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3
Q

Is still widely used as a POCT

A

Activated Clotting Time (ACT) Test

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4
Q

Screening Test

A
  1. Prothrombin Time
  2. Partial Thromboplastin Time
  3. PTT Mixing Studies
  4. Thrombin Clotting Time
  5. Venom Activated Assays
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5
Q

Reagents of PT

A

Thromboplastin
Phospholipids
Calcium Chloride

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6
Q

Recombinant or affinity-purified tissue factor suspended in phospholipids mixed with a buffered 0.025 M solution of calcium chloride

A

Prothrombin Time (PT)

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7
Q

It is most sensitive to factor VII deficiencies

A

Prothrombin Time (PT)

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8
Q

Is used most often to monitor the effects of therapy with Warfarin/Coumadin

A

Prothrombin Time (PT)

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9
Q

PT is typically reported as a combination of

A

PT (in seconds) and INR (as PT/INR)

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10
Q

PT Typical reference interval:

A

12.6- 14.6 seconds

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11
Q

Determine extrinsic and common pathway factor deficient

A

Prothrombin Time (PT)

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12
Q

Indicate if Normal or Decreased in Vitamin K deficiency

Factor V -
Factor VII -

A

Factor V - Normal
Factor VII - Decreased

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13
Q

Indicate if Normal or Decreased in Liver Disease

Factor V -
Factor VII -

A

Factor V - Decreased
Factor VII - Decreased

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14
Q

INR

A

International Normalized Ratio

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15
Q

ISI

A

International Sensitivity Index

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16
Q

INR formula:

A

INR = Patient or test PT x 100
———————————
Mean or Control PT

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17
Q

Is employed to monitor the effects of UFH and to detect LAC and specific coagulation factor antibodies(anti-factor VIII antibody)

A

Partial Thromboplastin Time (APTT)

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18
Q

Is prolonged in all congenital and acquired procoagulant deficiencies (except VII and XIII)

A

Partial Thromboplastin Time (APTT)

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19
Q

Partial Thromboplastin Time (APTT) Reference value:

A

26-38 seconds

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20
Q

Determined intrinsic and common pathway factor deficient

A

Partial Thromboplastin Time (APTT)

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21
Q

Monitors unfractionated heparin therapy

A

Partial Thromboplastin Time (APTT)

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22
Q

PTT reagent contains:

A
  • Phospholipid
  • Negatively charged particulate activator (kaolin, ellagic acid, silica, or celite)
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23
Q

Distinguish LACs from specific inhibitors and factor deficiencies

A

PTT Mixing Studies

24
Q

Commercially prepared bovine thrombin reagent cleaves fibrinopeptides A and B from plasma fibrinogen to form a detectable fibrin polymer

A

Thrombin Clotting Time

25
Q

Test for fibrinogen deficiency

A

Thrombin Clotting Time

26
Q

Is used to determine whether UFH is present whenever the PTT is prolonged

A

Thrombin Clotting Time

27
Q

Thrombin Clotting Time Typical reference range:

A

15-20 seconds

28
Q

Thrombin Clotting Time is prolonged when:

A
  • Fibrinogen is <100 mg/dL (hypofibrinogenemia)
  • Presence of antithrombotic materials (FDP, paraproteins, or UFH)
  • Presence of antithrombotic materials (FDP, paraproteins, or UFH)
29
Q

May also assess the presence of the oral direct thrombin inhibitor dabigatran

A

Thrombin Clotting Time

30
Q

a thrombin-like enzyme isolated from the venom of Bothrops atrox (lancehead viper)

A

Reptilase Time

31
Q

Cleaves fibrinopeptide A only

A

Reptilase Time

32
Q

Principle: reptilase catalyzes the conversion of fibrinogen to fibrin. In contrast to thrombin, this enzyme cleaves only fibrinopeptide A

A

Reptilase Time

33
Q

Insensitive to UFH and FXIII deficiency but is markedly prolonged in dysfibrinogenemia

A

Reptilase Time

34
Q

Useful for detecting hypofibrinogenemia or dysfibrinogenemia

A

Reptilase Time

35
Q

Also prolonged in the presence of FDP and paraproteins

A

Reptilase Time

36
Q

Reptilase Time Reference value

A

10-15 seconds

37
Q

Test for fibrinogen deficiency/fibrinogen
abnormality and It is not affected by Heparin/Heparin therapy

A

Reptilase Time

38
Q

triggers coagulation at the level of factor X

A

Russell Viper Venom Test

39
Q

is used to detect and confirm lupus anticoagulant.

A

Diluted Russell Viper Venom Test (DRVVT)

40
Q

Determines coagulation factor deficiency in the common pathway

A

Russell Viper Venom Test

41
Q

A modification of TCT and is the recommended procedure for estimating fibrinogen function

A

Fibrinogen Assay

42
Q

The interval to clot formation is inversely proportional to the concentration of functional fibrinogen

A

Fibrinogen Assay

43
Q

Reagents of Fibrinogen Assay:

A
  • Owren buffer
  • Bovine thrombin
44
Q

Factor VIII-depleted or –deficient PPP provides normal activity of all procoagulants except factor VIII

A

Single-Factor Assay using the PTT

45
Q

Single-Factor Assay using the PTT:

Factor VIII-depleted PPP (alone):

A

prolonged PTT (Factor VIII deficiency)

46
Q

Single-Factor Assay using the PTT:

Factor VIII-depleted PPP + Normal patient plasma:

A

PTT reverts to normal (Coagulation Factor Deficiency)

47
Q

Single-Factor Assay using the PTT:

Factor VIII-depleted PPP + Factor VIII-deficient patient plasma:

A

Prolonged (LAC)

48
Q

Confirms and quantifies anti-factor VIII inhibitor (typically IgG4-class immunoglobulin)

A

Nijmegen-Bethesda Assay

49
Q

Is expressed as a percentage of the control

A

Bethesda titer

50
Q

The percentage of factor VIII activity neutralized is proportional to the level of inhibitor activity

A

Bethesda titer

51
Q

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.

A

Single Factor Assays using the PT

52
Q

Quantification of factor XIII activity is based on the measurement of ammonia released during an in vitro transglutaminase reaction

A

Factor XIII Assays

53
Q

Decreased VWF:Ag, VWF:RCo, and Factor VIII:C

A

VWD Type I and III

54
Q

Decreased VWF:Ag, Factor VIII:C

A

VWD Subtypes 2A, 2B, 2M

55
Q

Decreased Factor VIII:C

A

Subtype 2N

56
Q

Give the clotting factor deficient in the following tests:

Nijmegen-Bethesda:
TCT:
Stypven Time (RVVT):
Reptilase Test:
Clause Test:
Technochron:

A

Nijmegen-Bethesda: Anti-factor VIII inhibitor
TCT: Factor I (affected by heparin)
Stypven Time (RVVT): Factor X
Reptilase Test: Factor I (unaffected by heparin)
Clauss Test: Factor I
Technochron: Factor XIII

🩸Hema🎀 (20 decks)

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