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Hematology > Laboratory Evaluation of Hemostasis > Flashcards

Laboratory Evaluation of Hemostasis Flashcards

1
Q

Hemostasis is dependent upon which factors?

5

A
  1. Vessel Wall Integrity
  2. Adequate Numbers of Platelets
  3. Proper Functioning Platelets
  4. Adequate Levels of Clotting Factors
  5. Proper Function of Fibrinolytic Pathway
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2
Q

Which three ways does the body achieve and make a stable hemostatic plug?3

A
  1. Blood Vessel Constriction (vasoconstriction)
  2. Platelet Aggregation (ahesion and activation too)
  3. Coagulation Cascade
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3
Q

What lab tests do we want to do for evaluation of hemostasis?
5

A 
PLATELET COUNT (plt)
BLEEDING TIME (BT)
PROTHROMBIN TIME (PT/INR)
ACTIVATED PARTIAL THROMBOPLASTIN TIME (aPTT)
THROMBIN TIME (TT)
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4
Q

What is the platelet count measuring?

What tube is it collected in?

A

The number of platelets per cubic millimeter of whole blood

Its on the CBC

Lavender top (EDTA)

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5
Q

What are the different ways to count platelets?

A
  1. Manual platelet counting
  2. Automated cell counter methods
    - Optical counting methods
    - Flow cytometric methods
  3. Platelet count ratio method for platelet function testing
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6
Q

Whats a normal platelet count?

What platelet count is considered thrombocytopenia?

What is considered mild thrombocytopenia?

What is consodered severe thrombocytopenia?

A

Adults: 150,000-450,000/mm3
Peds: 150,000-350,000 /mm3

Below 150,000

50,000-99,999 Mild

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7
Q

At what platelet count do you start experiencing symtpoms?

What count is potentially life threatening?

At what count are you at high risk for spontaneous bleeding and intracranial hemorrhage?

A

50,000 - 20,000: first symptoms

20,000-10,000

Below 10,000

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8
Q

If you have a high platelet count what could be happening?

5

A
  1. Acute phase reaction (most prominent is C reaction protein CRP)
  2. Early CML
  3. Essential thrombocytosis
  4. Polycythemia vera
  5. Post splenectomy (very common)
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9
Q

If you have a low platelet count what could be happening?

7

A
  1. DIC (sepsis and trauma)
  2. Hemolytic anemia
  3. Hypersplenism
  4. ITP
  5. Leukemia
  6. Prosthetic heart valve
  7. Recent transfusion
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10
Q

What does bleeding time measure?

Whats it a screening test for?

What is it useful for and what is it not useful for?

A

A measurement of the time required for bleeding from a superficial puncture to stop.

Platelet funtion

Not a reliable predictor of post-op bleeding

Useful in the diagnosis of Von Willebrand’s

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11
Q

What does bleeding time really measure?

A

how well platelets interact with blood vessel walls to form blood clots.

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12
Q

How often should we blot in a bleeding time test?

A

Blot incision q 30 seconds until bleeding stops

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13
Q

What should we avoid 2 weeks prior to a bleeding time test?

Whats the normal bleeding time?

A

Avoid aspirin 2 weeks prior to test

Normal: 3-8 minutes

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14
Q

What could indicate a high bleeding time?

7

A
  1. Platelet dysfunction
  2. DIC (but probably won’t do the test here)
  3. Leukemia
  4. Liver disease
  5. Thrombocytopenia
  6. Von Willebrand’s
  7. Vasculitis
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15
Q

What does prothrombin time measure?

A

Measures vitamin K dependent clotting ability, and extrinsic pathway

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16
Q

What is PT used to screen and monitor?

2

A

Used to screen for bleeding disorders

Used to monitor patients on warfarin

17
Q

What is prothrombin time lab filled in and how do we need to fill it?

A

Light blue top (citrate)
Fill tube completely
Avoid prolonged tourniquet use (hemoconcentration, hemolysis, lactic acid buildup. no more than 1 minute)
Correct ratio of blood to citrate is critical
prolonged storage of plasma shortens PT

18
Q

Whats a normal PT?

For DVT prophylaxis what do we want the INR to be?

For Mechanical valve and anti-phospholipid antibody syndrome what do we want the INR at?

What should we treat pregnant women with?

What should AFIB pts INR be at?

A

Adults PT/INR: 11-13 seconds 1-2

DVT prophylaxis (INR): 2-3

2.5-3.5

(can cause a lot of complications in pregnancy. treat with warfarin or aspirin but in pregnant women go for heparin)

2-3

19
Q

What conditions would be indicated with a high PT/INR?

5

A
  1. Anti-phospholipid antibody syndrome
  2. DIC
  3. Liver disease
  4. Vitamin K deficiency
  5. Factor II, V, VII, or X deficiency
20
Q

What is PTT?

What does it measure?
Which is generally measuring what?

A

ACTIVATED PARTIAL THROMBOPLASTIN TIME

A measure of the time taken for a clot to form in citrated blood following the addition of calcium and a phospholipid platelet substitute.

Effectiveness of the intrinsic pathway

21
Q

What is PTT used to work up, monitor, and screen?

3

A

Used to work up bleeding disorders
Used to monitor heparin therapy
Screen for lupus anticoagulant

22
Q

What do we collect PTT in and what do we need to remember to do while filling it?

A 
Light blue top (citrate)
Fill tube completely
Avoid prolonged tourniquet use
Correct ratio of blood to citrate is critical 
prolonged storage of plasma shortens PTT
23
Q

Whats the normal PTT in adults?

What about on antocoagulation therapy?

What is the normal PTT in peds?
Newborns:
1-6 yrs old:

A

Adults: 25-35 secs

On anticoagulant therapy: 1.5-2.5 x the control value

Newborn: 31-54 secs
1-6 yrs: 24-36

24
Q

What conditions would be indicated in a high PTT?

5

A 
Hemophilia
DIC
Liver disease
Vitamin K deficiency
Heparin therapy
25
Q

What lab is associated with the intrinsic pathway and what factors is it associated with?
4

A 
Think PTT (partial thromboplastin time) 
Think VIII, IX, XI, and XII
26
Q

What lab is associated with the extrinsic pathway and what factors is it associated with?2

A

Think PT(INR) (prothrombin time) Think II and VII

27
Q

What factors are vitamin K dependent?

A

Factors VII, X, and prothrombin (Factor II)

28
Q

What is thrombin time measuring?

Whats the normal thrombin time?

A

The rate of conversion of fibrinogen to fibrin in the final stage of coagulation as measured by the addition of thrombin to citrated blood.

Fibrinolytic pathway

15-20 secs

29
Q

What do we collect thrombin time in?

A

Light blue top (citrate)
Fill tube completely
Avoid prolonged tourniquet use
Correct ratio of blood to citrate is critical

30
Q

What would indicate a high thrombn time?

6

A
  1. DIC
  2. Liver disease
  3. Dysfibrinogenemia (abnirmal fibrinogen funtion- could cause
  4. bleeding or thrombosis)
  5. Paraprotienemia-monoclonal gammapathy
  6. Uremia
31
Q

What would a low thrombin time?

2

A

Erythrocytosis

Dysfibrinogenemia

32
Q

Indications to order coagulation studies ?

5

A
  1. Work-up of suspected bleeding disorders
  2. Screening before major surgery, part of pre-op evaluation
  3. Monitoring of medications (warfarin, heparin)
  4. Monitoring of bleeding disorders
  5. Monitoring of liver disease
33
Q

What pathway are we monitoring with heparin?

A

intrinsic/pt

34
Q

What pathway are we monitoring with warfarin?

A

extrinsic and ptt

35
Q

Whatdo we really want to know when someone presents with abnormal bleeding?

A

What is the bleeding site?

Multiple vs single sites
Joints
Deep muscle
Superficial cut
Skin or mucus membrane
Epistaxis
Gingivae
Urine, GI tract, Menstrual
36
Q

Platelet/cellular deficiency or malfunction will show bleeding where?
5

What will be normal and abnormal?
2

A 
Gum bleeding
Easy bruising
Epistaxis
Petechiae
Prolonged bleeding from minor cuts

Abnormal bleeding time, normal PT/PTT

37
Q

Factor deficiencies (hemophilia)
will show bleeding where?
5

What will normal and abnormal in the lab tests?
2

A 
Hemarthroses
Easy bruising
Delayed bleeding
Postop hemorrhage
Muscle hematoma

Normal bleeding time, abnormal PTT

Hematology (18 decks)

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