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Clin LAB Med > L2: Coagulation Studies > Flashcards

L2: Coagulation Studies Flashcards

1
Q

Is acquired or congenital platelet dysfunction more common?

A

Acquired

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2
Q

-Drugs (chemo, abx)
-Uremia
-Liver disease
-von Willebrand disease
-Myeloproliferative disease
can all cause?

A

acquired platelet dysfunction

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3
Q

How do you manage platelet platelet dysfunction?

A
  • Treat the underlying cause

- Platelet transfusion

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4
Q

What happens in splenic sequestration?

A

Splenomegaly (due to spleen eating up too many platelets) which results in thrombocytopenia

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5
Q

What are some examples of splenic sequestration?

A

Vascular congestion

Cirrhosis

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6
Q

What are the 4 types of increased platelet destruction disorders?

A
  1. Immune thrombocytopenia (ITP)
  2. Disseminated intravascular coagulation (DIC)
  3. Heparin-induced thrombocytopenia (HIT)
  4. Thrombotic microangiopathies (TMA)
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7
Q

What are the 2 subtypes of TMA?

A
  1. Thrombotic thrombocytopenic purpura (TTP)

2. Hemolytic-uremic syndrome (HUS)

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8
Q

Why does HIT occur? (Describe the process)

A

New onset (acquired) thrombocytopenia while on heparin therapy (UFH or LMWH):

  1. Anti-platelet antibodies cause platelet activation
  2. Increased risk of venous and arterial thrombosis
  3. Eventually leads to thrombocytopenia and prothrombotic state
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9
Q

Why does thrombocytopenia occur with TMA (including TTP and HUS)?

A

Incorporation of platelets into thrombi in the microvasculature and microangiopathic hemolytic anemia (there is mechanical shearing/fragmentation of RBCs as they pass through platelet rich microthrombi in microvasculature)

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10
Q

Which platelet disorder is an emergency?

A

Thrombotic thrombocytopenic purpura (type of TMA)

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11
Q

Who is most at risk for developing TTP?

A

Black females

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12
Q

What is the mechanism behind which TTP occurs? (differentiate between acquired vs. inherited)

A

Acquired: Autoantibodies are directed against ADAMTS-13 (seen in pregnancy)
Hereditary: Inherited ADAMTS-13 mutation

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13
Q

What happens (physiologically) with TTP?

A

Microthrombi formed throughout the body

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14
Q

What is the pentad for TTP?

A
  • Microangiopathic hemolytic anemia
  • Thrombocytopenia
  • Acute kidney injury (AKI)
  • Neurological deficits
  • Fever
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15
Q

What are other signs of TTP (outside of pentad)?

A
  • Purpura/petechiae
  • Pallor
  • Jaundice
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16
Q

What is another name for hemolytic uremic syndrome?

A

Shiga toxin-mediated HUS

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17
Q

Which population is most likely to develop HUS?

A

Children (be concerned if child presents with diarrhea (often bloody) and thrombocytopenia)

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18
Q

What is the etiology of HUS?

A

Shiga toxin-producing E. Coli

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19
Q

What is the primary symptom associated with HUS?

A

Recent or current diarrheal illness; often hemorrhagic

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20
Q

What is the HUS triad?

A
  • Microangiopathic hemolytic anemia
  • Thrombocytopenia
  • Acute kidney injury
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21
Q

Is an acute kidney injury more likely to occur in TTP or HUS?

A

HUS

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22
Q

What are the 4 lab findings associated with TMA (including abnormal/normal values)?

A
  1. Microangiopathic hemolytic anemia
  2. Thrombocytopenia
  3. PT and aPTT are normal
  4. Acute kidney injury
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23
Q

Schistocytes (helmet cells) are an indication of:

A

fragmented RBC’s (seen in microangiopathic hemolytic anemia)

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24
Q

What are the more specific lab values of microangiopathic hemolytic anemia (a lab finding for TMA)

A
  • Fragmented RBCs (Schistocytes)
  • Increased LDH and indirect bilirubin
  • Decreased serum haptoglobin
  • Negative Coombs test
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25
Q

What is the treatment for TMA?

A
  • Plasma exchange

- Supportive care (endemic diarrhea-associated HUS)

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26
Q

What are the differences and similarities between TTP and HUS?

A

Similarities: Microangiopathic hemolytic anemia, thrombocytopenia, AKI

Differences:
TTP: Neurologic deficits, fever, ADAMTS-13
HUS: E. Coli O157:H7

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27
Q

What are 5 causes of impaired platelet production?

A
  1. Congenital bone marrow failure
  2. Acquired bone marrow failure
  3. Exposure to chemotherapy, radiation
  4. Bone marrow infiltration (neoplastic, infectious)
  5. Nutritional (def. in B12, folate, or iron/alcohol)
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28
Q

What are 3 commonly ordered studies to assess coagulation?

A

PTT/aPTT
Anti-factor Xa
PT/INR

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29
Q

What does a PTT/aPTT study test for?

A
  • Evaluates INTRINSIC and COMMON pathways

- Used to monitor UNFRACTIONATED HEPARIN therapy

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30
Q

What does Anti-factor Xa test for?

A

Used to monitor UNFRACTIONATED HEPARIN and LOW MOLECULAR WEIGHT HEPARIN therapy

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31
Q

Is PTT/aPTT or anti-Xa preferred?

A

anti-Xa (more commonly used now)

32
Q

What coagulation study is used to monitor unfractionated heparin therapy?

A

PTT/aPTT

33
Q

What coagulation study is used to monitor LMWH therapy?

A

Anti-Xa

34
Q

What is a PT test used to evaluate?

A

Evaluates the EXTRINSIC and COMMON pathways

-Used to monitor WARFARIN (Coumadin) therapy

35
Q

What is an INR test used to evaluate?

A
  • More accurate reflection of PT
  • Calculated as a ratio of the patient’s PT to a control PT
  • Used to monitor WARFARIN (Coumadin) therapy
36
Q

What coagulation study is used to monitor Warfarin therapy?

A

PT or INR

37
Q

What is the goal INR dependent on?

A

Underlying need for anticoagulation

38
Q

What coagulation study differentiates between coagulation factor deficiency vs. inhibitor problem?

A

Inhibitor screening (mixing test)

39
Q

Which coagulation study measures the final step of coagulation (the conversion of fibrinogen to fibrin)

A 
Thrombin time (TT)
*Not used as an initial screen
40
Q

What do low levels of fibrinogen indicate?

A

Can result in impaired clot formation and increased bleeding risk

41
Q

What are the components of a hypercoagulable panel?

A
  • Antithrombin
  • Factor V-Leiden
  • Protein C
  • Protein S
  • Prothrombin gene mutation
  • Lupus anticoagulant (antiphospholipid antibodies)
  • MTHFR gene
42
Q

Which anticoagulant medication is given inpatient only?

A

Unfractionated heparin (UFH)

43
Q

Which 2 anticoagulation meds are initially given together?

A

LMWH and Warfarin

44
Q

If a patient has poor renal function or is on dialysis, what is the only anticoagulation tx option? What meds should be avoided?

A

Treat with Warfarin (No DTI or Anti Xa)

45
Q

What are the 5 kinds of anticoagulation medications?

A
  • UFH
  • LMWH
  • Warfarin (coumadin)
  • Direct thrombin inhibitors*
  • Direct Xa inhibitors*
  • Also known as DOACs (direct oral anticoagulants)
46
Q

Which anticoagulation medication can be given as a SubQ injection?

A

Lovenox (Coumadin)

47
Q

What medication takes time to work?

A

Warfarin

48
Q

What anticoagulant can be given to a pregnant women?

A

Heparin (no coumadin!)

49
Q

When is it reasonable to switch a patient to a DOAC from Heparin (time)?

A

Following 5-10 days of therapy with parenteral anticoagulant

50
Q

What are the 4 Factor Xa inhibitors?

A

Arixtra
Xarelto
Eliquis
Savaysa, Lixiana

51
Q

What is the name of the DTI?

A

Dabigatran (Pradaxa)

52
Q

What is the recommended tx for patients with a DVT or PE without an underlying malignancy?

A

DOACs are recommended over warfarin

53
Q

What is the recommended tx for patients with a DVT or PE in the setting of an underlying malignancy?

A

LMWH

54
Q

What baseline labs should be ordered for a patient on UFH? What labs do you order for monitoring?

A

Baseline: aPTT, PT/INR, CBC

Monitoring: aPTT or Factor Xa

55
Q

What baseline labs should be ordered for a patient on LMWH? What labs do you order for monitoring?

A

Baseline: aPTT, PT/INR, CBC, Creatinine* (pt can become anemic)

Monitoring: None (if required, anti-Xa activity testing)

56
Q

What is a therapeutic INR for someone with aFib or DVT?

A

2-3

57
Q

What baseline labs should be ordered for a patient on DOAC? What labs do you order for monitoring?

A

Baseline: PT/INR, CBC, Creatinine

Monitoring: None (if required, anti-Xa activity testing)

58
Q

What baseline labs should be ordered for a patient on Warfarin? What labs do you order for monitoring?

A

Baseline: aPTT, PT/INR, CBC, Creatinine, LFTs (may have to adjust dose depending on liver function)

Monitoring: PT/INR

59
Q

What is the initial dose of Warfarin that should be given?

A

5mg/day (then adjust coumadin dosing based on INR; different for everyone and specific to each patient)
*NO LOADING DOSES

60
Q

How do you bridge a pt from parental therapy (UFH/LMWH) to Warfarin?

A

Parental therapy (UFH/LMWH) should overlap with warfarin for at LEAST 5 days and until INR is therapeutic for a minimum of 24 hours or 2 consecutive days

61
Q

How do you monitor a patient on warfarin (in general)?

A
  • Titrate dose to appropriate INR
  • Monitor INR frequently (daily then weekly, every 2-4 weeks once stabilized)
  • Adjust dose as necessary
62
Q

What is the target INR for prophylaxis?

A

1.5-2.0

63
Q

What is the target INR for VTE?

A

2.0-3.0

64
Q

What is the target INR for Afib?

A

2.0-3.0

65
Q

What is the target INR for mechanical mitral valve?

A

2.5-3.5

66
Q

What is the target INR for mechanical aortic valve?

A

2.0-3.0

67
Q

What 5 things should we educated patients about while on anticoagulation therapy?

A
  • Coumadin log
  • Drug-drug interactions
  • Diet
  • Risks
  • Proper follow-up and monitoring of PT/INR
68
Q

What does supratherapeutic INR mean?

A

Reversal of anticoagulation (like if patient is bleeding or INR too high)

69
Q

What is the tx for a patient with an INR 4.5-10 and no evidence of bleeding?

A

Hold warfarin and recommended use of PO vitamin K is variable

70
Q

What is the tx for a patient with an INR >10 and no evidence of bleeding?

A

Hold warfarin and give PO vitamin K

71
Q

What is the tx for a patient with VKA (coumadin) associated major bleeding?

A

Hold warfarin, rapid reversal of warfarin with prothrombin complex concentrate (PCC), give IV vitamin K

72
Q

Protamine (PER977) is the reversal agent for

A

UFH and LMWH

73
Q

What are the reversal agents for Warfarin?

A
  • 4Factor-PCC

- Vitamin K

74
Q

What are the reversal agents for DTIs?

A
  • Praxbind
  • Supportive care for non-life threatening bleed
  • PER977

*New school drugs are better and more convenient but we don’t have great reversal agents yet

75
Q

What are the reversal agents for Direct Xa inhibitors?

A
  • Supportive care for non-life threatening bleed
  • Andexanet
  • PER977

*New school drugs are better and more convenient but we don’t have great reversal agents yet

Clin LAB Med (4 decks)

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