Lab eval of Hemostasis Flashcards

1
Q

Hemostasis is dependent upon?

A
  • vessel wall integrity
  • adequate number of platelets
  • proper functioning platelets
  • adequate levels of clotting factors
  • Proper function of firbinolytic pathway
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2
Q

What are the lab tests used to evaluate hemostasis?

A
  • Platelet count (plt)
  • Bleeding Time (BT)
  • Prothrombin Time (PT/INR)
  • Activated Partial Thromboplastin Time (aPTT)
  • Thrombin Time
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3
Q

What is platelet count? What are the various methods for finding this value?

A
  • number of platelets
  • on CBC
  • manual platelet count
  • automated cell counters (Optical and flow cytometric)
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4
Q

What is normal platelet count? Considered Thrombocytopenia? Severe? Bleed by blink?

A

-150,000-400,000/mm^3: no sx

-

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5
Q

What conditions cause platelets to be high?

A

-acute phase rxn
(Group of physiological process right after onset of severe infection, trauma, inflamm processes, malignancy,
Most dramatic change in acute phase reaction–CRP levels will be high, fever, increased vascular permeability )

  • early CML
  • essential thrombosis
  • polycythemia vera
  • post splenectomy
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6
Q

What conditions cause platelets to be low?

A
  • DIC
  • hemolytic anemia
  • Hypersplenism
  • ITP
  • Leukemia
  • Prosthetic heart valve
  • recent transfusion
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7
Q

What is Bleeding Time? What does it really measure?

A
  • a measurement of the time required for bleeding from a superficial puncture to stop.
  • how well platelets interact w/ blood vessel walls to form blood clots.
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8
Q

What screening test is used for platelet dysfunction?

A

-bleeding time

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9
Q

Bleeding time is useful in the dx of what disorder?

A

-dx of vonWillebrands

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10
Q

How to perform the bleeding time test? What a normal time?

A
  • puncture forearm making a 5mmx1mm deep cut
  • blot incision q 30seconds until bleeding stops

normal time is 3-8mins

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11
Q

What conditions cause bleeding time to be high?

A
  • platelet dysfunction
  • DIC
  • leukemia
  • liver disease
  • thrombocytopenia
  • vonWillebrands
  • Vasculitis
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12
Q

Prothrombin Time measures what?

When is this commonly used?

A

Vit K dependent clotting ability and the extrinsic pathway

  • to screen for bleeding disorders
  • to monitor warfarin

*INR has been introduced to reduce inter lab variabliity in reporting PT

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13
Q

PT synonyms

A

PT/INR
INR
Protime

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14
Q

What are some of the PT/INR values?

  • normal
  • DVT prophylaxis
  • Mechanical Valve
  • Anti-phosphoplipid aby syndrome
A

Normal Adult: 11-13 secs 1-2

DVT prophylaxis INR: 2-3

Mechanical Valve and Anti-phospholipid aby syndrome INR: 2.5-3.5

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15
Q

Reasons for High PT

A

anti-phospholipid aby syndrome

DIC

Liver Disease

Vit K deficiency

Factor II, V, VII, or X deficiency

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16
Q

What is Partial Thromboplastin Time?

A

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

17
Q

PTT mesaures the effectiveness of which pathway? Used to monitor which type of theapy?

A
  • Intrinsic

- Heparin

18
Q

What are some of the values of PTT?

  • normal
  • pt on anti-coagulation therapy
  • peds
A

Normal: 25-35secs
*on anticoagulant therapy: 1.5-2.5x the control value

Peds:
Newborns: 31-54sec
1-6years: 24-36sec

19
Q

When would there be high levels of PTT?

A
  • Hemophilia
  • DIC
  • Liver Disease
  • Vit K
  • Heparin Therapy
20
Q

What lab test is ordered and what drug does this monitor when looking at the intrinsic pathway? Extrinsic?

A
  • Intrinsic pathway, order PTT, monitors heparin therapy

- Extrinsic pathway, order PT, monitors warfarin therapy

21
Q

Which factors in the coagulation cascade are vit K dependent?

A

-VII, X, and prothrombin (II) are vit. k dependent and are altered by warfarin.

22
Q

What is thrombin time? Whats a normal time?

A
  • the rate of conversion of fibrinogen to fibrin

- 15-20sec

23
Q

What are some disorders of high Thrombin Time?

A
  • DIC
  • Liver Disease
  • Dysfibrinogenemia
  • Paraproteinemia
  • Uremia
24
Q

What are some disorders of low thrombin time?

A
  • erythrocytosis

- dysfibrinogenemia

25
Q

What are some indications to order coagulation studies?

A
  • work up of suspected bleeding disorders
  • screening before major surgery, part of pre-op values
  • Monitor meds (warfarin, heparin)
  • Monitor of bleeding disorders
  • monitor liver disease
26
Q

Clinical Differences between:

Platelet/cellular deficiency/malfunction & Factor Deficiencies (hemophilia)

A

Platelet/cellular:

  • gum bleeding
  • easy bruising
  • epistaxis
  • petechiae
  • prolonged bleeding from minor cuts
  • Abnormal bleeding time, normal PT/PTT.

Factor Deficiencies:

  • hemarthroses
  • easy bruising
  • delayed bleeding
  • postop hemorrhage
  • muscle hematoma
  • Normal bleeding time, abnormal PTT