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1) Hemostasis Part 3 > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

This coagulation method includes:

all reagents and specimens are added manually by operator. Temperature is maintained by a heat block. End point is determined visually by the operator

a) Activated Time Factor
b) Reptilase time
c) 50:50 Mix
d) Manuel Tilt Tube Method

A

Manuel Tilt Tube Method

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2
Q

What are the five principles of Coagulation Instrumentation?

A
  • Mechanical
  • Photo-optical (turbidometric)
  • Nephelometric
  • Chromogenic (amidolytic)
  • Immunologic
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3
Q

This type of principle measures the change in conductivity between 2 metals probes immersed in plasma (one stationary and one moving).

Electrical current between 2 probes is not maintained. When a fibrin clot forms it completes the circuit and stops the timer.

A

Electromechanical clot detection (mechanical)

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4
Q

This type of principle detects the change in movement of the steel ball by changing its range of motion ore a break in contact with magnetic sensors.

As clot forms there is an increases viscosity of the test solution

A

Magnetically Monitoring (mechanical)

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5
Q

This principle measures the change in OD of a test sample.

Light of a specific wavelength is passed through a sample. As fibrin clot forms the plasma becomes more opaque(not transparent) decreasing the amount of light detected.

A

Photo-optical (turbometric)

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6
Q

This type of principle detects variation in light scatter at 90 degrees (side) and 180 degrees (forward).

This is an immunometric (by using antibodies) method for measuring proteins. This is done by using antigen-antibody complexes precipitate causing turbidity that scatters light.

If immune complexes are too small for detection the antibodies are attached to latex particles

A

Nephelometric

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7
Q

This type of coagulation method is based on the use of color producing substance, specifically para-nitroaniline (pNA).

The goal is for the coagulation protein (a protease) to attack the chromogenic substrate freezing the pNA

  • Free pNA is yellow; the color intensity is proportional to the amount of protease activity.
A

Chromogenic (amidolytic)

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8
Q

This type of coagulation method is based on antigen-antibody REACTIONS. (Microlatex particles coated with a specific Ab to analyze.

A beam of monochromatic light is passed through the suspension. When the wavelength of light is greater than the diameter of the particles, only a small amount of light is absorbed.

When Ag-Ab complexes form, particles will agglutinate and absorb more light. This is proportionate to Thea antigen level present in sample.

A

Immunologic (End Point)

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9
Q

This principle involves Microlatex particles coated with a specific Ab to analyte. when Ag-Ab complexes form, particle will agglutinate and absorb more light. What principle is this?

A

Immunologic (End point)

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10
Q

*Which factors are tested in the Prothrombin Time (PT) test?

A

Factors VII, X, V, II, and I

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11
Q

Which pathway does Prothrombin Time test for?

A

Extrinsic Pathway

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12
Q

What type of sample is used for Prothrombin time (PT)?

A

Platelet Poor Plasma

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13
Q

What reagents are used for Prothrombin time (PT)?

A

Thromboplastin

This reagent has a phopholipid and we add CaCl2 to override the sodium citrate.

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14
Q

This procedure involves Thromboplastin to be warmed up to 37C in a separate tube. In another separate tube, the patient’s PPP is warmed up to 37C. After they have been warmed up, we add thromboplastin to patient specimen and observed for clot formation. The time is recorded for clot to form. What procedure is this?

A

Prothrombin Time (PT)

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15
Q

True or False: PT tests for TF-III, Ca++, and/or PF3, and XIII.

A

False.
- It cannot test for TF-III, Ca++ or PF3 for it’s already included in the reagents.
- It does not test for Factor XIII ( There’s a separate test that test for the stabilization of the clot)
-It is insensitive to the alternate pathway of factor VIIa activation of Factor IX.

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16
Q

What is the OHSU reference range for PT?

A

11 - 13 seconds

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17
Q

Prothrombin time is used to monitor effects of oral anticoagulants. What range should these patients have of PT?

A

20 - 27 seconds

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18
Q

What Is INR?

A

INR stands for International Normalized Ratio.

This “correction” standardizes patient results between laboratories.

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19
Q

This ratio is used when a patient is placed on oral anticoagulant therapy, the affected factors (magic 4) are not decreased in concentration, they are simply produced in an incomplete form. –> PIVKA

A

INR

20
Q

What is PIVKA?

A

proteins induced by Vitamin K absence or antagonist or PIVKA.

PIVKAs will have some effect on the PT. How much effects depends on how SENSITIVE THE REAGENT used is to the presence of PIVKAs.

Each commercial reagent has been assign an International Sensitivity index (ISI) by the WHO. The resenfrerence thromboplastin is assisned a value of 1. The FARTHER the ISI is from 1, the less sensitive it its to PIVKAs.

This allows us to “correct” a patient’s PT results based on the sensitivity of the reagents and instrumentation used.

21
Q

What is ISI?

A

Each commercial reagent has been assign an International Sensitivity index (ISI) by the WHO. The resenfrerence thromboplastin is assisned a value of 1. The FARTHER the ISI is from 1, the less sensitive it its to PIVKAs.

This allows us to “correct” a patient’s PT results based on the sensitivity of the reagents and instrumentation used.

22
Q

How do you calculate the INR?

A

(patients PT / Normal PT) ^ (ISI)

23
Q

What is the OHSU reference range for INR?

A

0.9-1.2

24
Q

What is the therapeutic reference range / range for INR?

For patients on anticoagulant

A

roughly 2.0-3.0

25
Q

Which pathway does the Activated Partial Thromboplastin Time (APTT) participate in?

A

Intrinsic Pathway

26
Q

Which factors does the Activated Partial Thromboplastin Time test?

A

Factors XII, XI, IX, VIII, X, V, II, I HMWK, and PK

27
Q

What sample is used for the APTT?

A

patient poor plasma

28
Q

What reagents are used for the APTT?

A
  • Activator reagent (like elite, kaolin, ellagic acid or silica) (STA-PPT-A-5 - silica and cephalin from rabbits brain and phospholipids (PF3 substitute)
  • and CaCl2
29
Q

This procedure involves the activator reagent being mixed with patient PPP. This combination is warmed at 37C. During this incubation factor XII is activated. Prewarmed CaCl2 is added next to initiated the clotting process. Time is required for the clot to form. What procedure is this?

A

APTT

30
Q

What three things does the APTT does not measure?

A
  • PF3
  • Ca++
  • Factors XIII
31
Q

What is OHSU reference range for APTT?

A

26-36 seconds

32
Q

APPT monitors the effects of _______.

A

Heparin

33
Q

Patients that are on Heparin should have an APTT of

A

1.5-2.5 times their normal value.

34
Q

Which test(s) help monitor Warfarin (Coumadin)?

A

PT and INR

35
Q

Which test(s) help monitor Heparin?

A

APTT

36
Q

If PT is normal and APTT is prolonged, what are the possible deficient factors?

A

Factors XII, XI, IX, VIII HMWK, PK

37
Q

If PT is prolonged and APTT is normal, what are the possible deficient factors?

A

Factors: VII

38
Q

If PT is prolonged and APTT is prolonged, what are the possible deficient factors?

A

Factors: X, V, II, I

39
Q

What does Thrombin Time (TT) test for?

What is the reagent?

A
  • Tests for the adequacy of Fibrinogen.
  • ## Reagent - dilute ThrombinIt measures how long the blood’s plasma takes to form a clot.
40
Q

What is the procedure of Thrombin Time? (TT)

A
  • Dilute Thrombin is warmed to 37C in a tube
  • In a separate tube, patient PPP is warmed to 37C
  • Once both are warmed, we add the prewarmed thrombin to the patient PPP tube
  • We record when clot has been form.
41
Q

What is OHSU reference range for TT?

A

14 - 20 seconds

42
Q

If one of the coagulation screening tests is prolonged (PT, APTT, or TT), we should determine if the abnormality is due to a factor deficiency or an inhibitor by using which test?

A

50:50 Mix

43
Q

What is the procedure for the 50:50 mix?

What is the interpretation?

A

We mix normal plasma and patient plasma in a 1:1 ratio and repeat the abnormal test.

If the prolonged test was caused by a factor deficiency, the ADDITION OF NORMAL PLASMA should cause a significant CORRECTION in the prolonged results.

If the abnormal test is due to the an inhibitor the test should REMAIN PROLONGED since the inhibitor will also inhibit the normal plasma.

44
Q

What test is called a corrected thrombin time when performed using the TT?

A

50:50 mix

45
Q

What does the Fibrinogen Assay test for?

A
  • Immunological Fibrinogen –> The total Fibrinogen
  • Fibrinogen Activity –> Fibrinogen level
46
Q

Fibrinogen Assay quantitates Fibrinogen activity

A

1) Hemostasis Part 3 (2 decks)

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