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Hematology MLT Unit 5 > Fibrinogen, Thrombin, and the Fibrinolytic System > Flashcards

Fibrinogen, Thrombin, and the Fibrinolytic System Flashcards

1
Q

What is the reference range for Fibrinogen?

A

200 - 400 mg/dl

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2
Q

Fibrinogen is converted to fibrin under the influence of _____ and is the onset of a ___ ____

A

Thrombin, solid clot

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3
Q

Fibrin in cleaved into what? (3)

A

Fibrin, fibrinopeptides A and B

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4
Q

What disassociates a clot a few hours after it has been formed?

What is trapped within the soluble clot? (4)

A
  • Fibrinolytic system
  • Thrombin,
  • antiplasmins,
  • plasminogen A,
  • and tPA
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5
Q

As an acute phase reactant, fibrinogen will have transient increases when? (5)

A
  • Inflammation
  • Preganancy
  • Stress
  • Diabetes
  • Oral contraceptives
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6
Q

What patients demonstate acquired increases in fribrinogen? (2)

A
  • Hepatitis
  • Artherosclerosis
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7
Q

What acquired disorders result in a decrease in fibrinogen? (3)

A

ADA

  • Acute liver disease
  • DIC (disseminated intravascular coagulation)
  • Acute renal disease
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8
Q

What is Afibrinogenemia?

How much fibrinogen is in plasma?

Symptoms?

A
  • Autosomal Recessive
  • < 10 mg/dL of fibrinogen in plasma
  • Umbilical bleeding, delayed healing cord, poor wound healing
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9
Q

What Lab results would you see in Afibrinogenemia? (3)

A
  • Increased PT, APTT, TT (throbmin time) and reptilase time
  • Abnormal PLT aggreagation with most aggregating agents
  • Elongated BT (bleeding time)
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10
Q

What is Hypofibrinogenemia?

How much fibrinogen is present in plasma?

Symptoms?

A
  • Heterozygous form of Afribrinogenemia
  • 20 - 100 mg/dL of fibrinogen in plasma
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11
Q

What is Dysfibrinogenemia?

Genetic inheritance?

A
  • Qualitative disorder of fibrinogen - molecule does not work properly
  • Auto. Dom. - inhereted homo and hetero
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12
Q

What lab findings would you see in Dysfibrinogenemia? (3)

Include how immuno assays are affected/not affected.

A
  • Increased PT, APTT, TT, and RT (reptilase time)
  • Normal immunologic assay
  • quantitative fibrinogen assay is abnormal
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13
Q

Thrombin participates in what PLT reactions? (2)

A
  • Release reaction
  • Aggregation
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14
Q

What PLT inhibitor does thrombin stimulate?

A

Prostacyclin

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15
Q

What factors does thrombin activate once the coagulation sytem has been activated? (2)

which are key factors in the formation of what?

A
  • Factor V
  • Factor VIII
  • Thrombus formation
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16
Q

What is a naturally occuring coagulation inhibitor, activated by thrombin and amplified by thrombomodulin.

A

Protien C

17
Q

What is the key role of thrombin in fibrinolysis

A

negative feedback, converting plasminogen to plasmin

18
Q

What is Plasminogen and what does it do?

Half life?

What is it converted to and what is involved?

A
  • Plasma enzyme made in the liver
  • Digest fibrin and fibrinogen
  • 48hr half life
  • converted to plasmin via action of tPA (tissue plasmin activator)
19
Q

What are the activators in the fibrinolytic system? (5)

A
  • tPA
  • Factor XIIa
  • Kallikrein
  • HMWK
  • Urokinase
20
Q

What are the inhobitors in the fibrinolytic system? (2)

A
  • Plasminogen activator inhibitor 1 (PAI-1)
  • Aplha-2 antiplasmin
21
Q

What are the secondary fibrinolysis inhibitors in the fibrinolytic system? (3)

A
  • a-1 antitrypsin
  • a2-macroglobulin
  • C1 inactivator
22
Q

Products of fibrinolyis: What are the fibrin splint/ degradation products?

A

Composed of fibrin fragments:

  • X
  • Y
  • D
  • E
  • D-D (D-dimers)
23
Q

Describe plasmin in terms of activation?

What clinical conditions are these activators used?

A

Activation:

  • tPA
    • released from endothelial cell damage
    • helps convert plasminogen to plasmin
    • Used during stroke episode
  • Urokinase
    • Minimal effect in clot dissolution
    • used in stroke, heart attack and thrombotic episodes
24
Q

Describe plasmin in terms of inhibition?

A
  • Plasminogen activator inhibitor 1 (PAI-1)
    • Supresses tPA
    • secreted by endothelial cells during injury
  • a2-antiplasmin
    • prevents plasmin binding fibrin (stop lysing - negative feedback)
    • MOST IMPORTANT INHIBITOR OF FIBRINOLYTIC SYSTEM!
25
Q

What are the serum dilutions for measuring fibrin split/degradation products?

A
  • 1:15
  • 1:20
26
Q

What are the normal serum values of fibrin split/degradation products?

A

<40 ug/ml

27
Q

What does the D-dimer lab test measure?

A

degradation of cross-linked fibrin only

28
Q

D-Dimers are released from ____ _____ _____.

A

Plasmin dissolved clot

29
Q

What are D-dimer assays useful for?

A

monitoring thrombolytic therapy

30
Q

What is the normal amount of d-dimers?

What causes an increase in D-dimers?

A
  • <0.5 ug/ml
    • Excessive clotting
31
Q

What is the D-dimer assay used for?

A

assess thromboembolic episodes, i.e. DVT and or Pulmonary Embolism (PE)

32
Q

What is DIC?

What can it lead to?

A

Hemostaic system unbalanced that may hyperactivate one or both the coagulation or fibrinolytic systems.

  • can lead to excessive disposition of thrombi
  • excessive hemorrhage

Almost always unanticipated and FATAL

33
Q

What events can trigger DIC? (5)

A
  • Infections (sepsis)
    • Gram +ve and Gram -ve bacteria
  • Tissue injury (trauma)
    • Crush injury
    • burns
    • massive head trauma
  • Malignancy
    • acute promyeolycitic leukemia
    • acute monoblastic/myeblastic leukemia
    • macroandiopathic dicorders
    • TTP
    • heatstroke
  • GI (acute hepatits)
  • Obstetrical complications
    • Maternal Toxemia
    • abruptio placentae
    • hemolytic diseases of newborn
    • Group B strep. infection
    • retained dead fetus
  • Other
    • ​Snake bites
    • heparin-induced thrombosis
    • septic shock
    • graft versus host disease
34
Q

What are the sysmptoms of DIC?

A
  • Skin and mucous membrane
    • Ecchymosis
    • Epistaxis
    • Petechae
  • Thrombotic episodes
    • Acrocyanosis
    • hypotension
    • shock
35
Q

A patient with DIC may develop microangiapthic hemolytic anemia (MHA) due to?

A

microthrombi disposition in the small vessels?

36
Q

Where are microthrobi seen? (4)

A
  • nose
  • genitals
  • digits
  • major organs (kidney, liver, or brain)
37
Q

What will be observed in the peripheral smear of a patient with DIC?

A

Shistocytes

38
Q

What is increased and deacreased in a DIC Lab profile?

A
  • Incresed:
    • PT
    • APTT
    • TT
    • D-dimer
    • FDP
    • Decreased:
      • Fibrinogen
      • PLT count
39
Q

How is DIC managed (treated)?

A
  • antibiotics in the case of septicemia may stem bleeding episode
  • Surgery for obstetrical complications
  • Blood products as needed:
    • FFP (SOURCE OD ALL CLOTTING FACTORS)
    • pRBCs (restore oxygen carrying capacity)
    • PLT concentrates (enable clot formation)
  • Heparin in combination with antithrombin

Hematology MLT Unit 5 (5 decks)

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