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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
What is the treatment for TMA?
- Plasma exchange | - Supportive care (endemic diarrhea-associated HUS)
26
What are the differences and similarities between TTP and HUS?
Similarities: Microangiopathic hemolytic anemia, thrombocytopenia, AKI Differences: TTP: Neurologic deficits, fever, ADAMTS-13 HUS: E. Coli O157:H7
27
What are 5 causes of impaired platelet production?
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)
28
What are 3 commonly ordered studies to assess coagulation?
PTT/aPTT Anti-factor Xa PT/INR
29
What does a PTT/aPTT study test for?
- Evaluates INTRINSIC and COMMON pathways | - Used to monitor UNFRACTIONATED HEPARIN therapy
30
What does Anti-factor Xa test for?
Used to monitor UNFRACTIONATED HEPARIN and LOW MOLECULAR WEIGHT HEPARIN therapy
31
Is PTT/aPTT or anti-Xa preferred?
anti-Xa (more commonly used now)
32
What coagulation study is used to monitor unfractionated heparin therapy?
PTT/aPTT
33
What coagulation study is used to monitor LMWH therapy?
Anti-Xa
34
What is a PT test used to evaluate?
Evaluates the EXTRINSIC and COMMON pathways | -Used to monitor WARFARIN (Coumadin) therapy
35
What is an INR test used to evaluate?
- 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
What coagulation study is used to monitor Warfarin therapy?
PT or INR
37
What is the goal INR dependent on?
Underlying need for anticoagulation
38
What coagulation study differentiates between coagulation factor deficiency vs. inhibitor problem?
Inhibitor screening (mixing test)
39
Which coagulation study measures the final step of coagulation (the conversion of fibrinogen to fibrin)
``` Thrombin time (TT) *Not used as an initial screen ```
40
What do low levels of fibrinogen indicate?
Can result in impaired clot formation and increased bleeding risk
41
What are the components of a hypercoagulable panel?
- Antithrombin - Factor V-Leiden - Protein C - Protein S - Prothrombin gene mutation - Lupus anticoagulant (antiphospholipid antibodies) - MTHFR gene
42
Which anticoagulant medication is given inpatient only?
Unfractionated heparin (UFH)
43
Which 2 anticoagulation meds are initially given together?
LMWH and Warfarin
44
If a patient has poor renal function or is on dialysis, what is the only anticoagulation tx option? What meds should be avoided?
Treat with Warfarin (No DTI or Anti Xa)
45
What are the 5 kinds of anticoagulation medications?
- UFH - LMWH - Warfarin (coumadin) - Direct thrombin inhibitors* - Direct Xa inhibitors* * Also known as DOACs (direct oral anticoagulants)
46
Which anticoagulation medication can be given as a SubQ injection?
Lovenox (Coumadin)
47
What medication takes time to work?
Warfarin
48
What anticoagulant can be given to a pregnant women?
Heparin (no coumadin!)
49
When is it reasonable to switch a patient to a DOAC from Heparin (time)?
Following 5-10 days of therapy with parenteral anticoagulant
50
What are the 4 Factor Xa inhibitors?
Arixtra Xarelto Eliquis Savaysa, Lixiana
51
What is the name of the DTI?
Dabigatran (Pradaxa)
52
What is the recommended tx for patients with a DVT or PE without an underlying malignancy?
DOACs are recommended over warfarin
53
What is the recommended tx for patients with a DVT or PE in the setting of an underlying malignancy?
LMWH
54
What baseline labs should be ordered for a patient on UFH? What labs do you order for monitoring?
Baseline: aPTT, PT/INR, CBC Monitoring: aPTT or Factor Xa
55
What baseline labs should be ordered for a patient on LMWH? What labs do you order for monitoring?
Baseline: aPTT, PT/INR, CBC, Creatinine* (pt can become anemic) Monitoring: None (if required, anti-Xa activity testing)
56
What is a therapeutic INR for someone with aFib or DVT?
2-3
57
What baseline labs should be ordered for a patient on DOAC? What labs do you order for monitoring?
Baseline: PT/INR, CBC, Creatinine Monitoring: None (if required, anti-Xa activity testing)
58
What baseline labs should be ordered for a patient on Warfarin? What labs do you order for monitoring?
Baseline: aPTT, PT/INR, CBC, Creatinine, LFTs (may have to adjust dose depending on liver function) Monitoring: PT/INR
59
What is the initial dose of Warfarin that should be given?
5mg/day (then adjust coumadin dosing based on INR; different for everyone and specific to each patient) *NO LOADING DOSES
60
How do you bridge a pt from parental therapy (UFH/LMWH) to Warfarin?
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
How do you monitor a patient on warfarin (in general)?
- Titrate dose to appropriate INR - Monitor INR frequently (daily then weekly, every 2-4 weeks once stabilized) - Adjust dose as necessary
62
What is the target INR for prophylaxis?
1.5-2.0
63
What is the target INR for VTE?
2.0-3.0
64
What is the target INR for Afib?
2.0-3.0
65
What is the target INR for mechanical mitral valve?
2.5-3.5
66
What is the target INR for mechanical aortic valve?
2.0-3.0
67
What 5 things should we educated patients about while on anticoagulation therapy?
- Coumadin log - Drug-drug interactions - Diet - Risks - Proper follow-up and monitoring of PT/INR
68
What does supratherapeutic INR mean?
Reversal of anticoagulation (like if patient is bleeding or INR too high)
69
What is the tx for a patient with an INR 4.5-10 and no evidence of bleeding?
Hold warfarin and recommended use of PO vitamin K is variable
70
What is the tx for a patient with an INR >10 and no evidence of bleeding?
Hold warfarin and give PO vitamin K
71
What is the tx for a patient with VKA (coumadin) associated major bleeding?
Hold warfarin, rapid reversal of warfarin with prothrombin complex concentrate (PCC), give IV vitamin K
72
Protamine (PER977) is the reversal agent for
UFH and LMWH
73
What are the reversal agents for Warfarin?
- 4Factor-PCC | - Vitamin K
74
What are the reversal agents for DTIs?
- 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
What are the reversal agents for Direct Xa inhibitors?
- 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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