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X Clin Lab Med > Coagulation Studies > Flashcards

Coagulation Studies Flashcards

1
Q

What is microangiopathic hemolytic anemia?

A

Mechanical shearing (fragmentation) or RBCs as they pass through platelet rich microthrombi in microvasculature

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2
Q

What is heparin induced thrombocytopenia?

A

New onset thrombocytopenia/thrombus while on heparin therapy
Antiplatelet antibodies cause platelet activation- increased risk of thrombosis- lead to thrombocytopenia and prothrombotic states

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3
Q

Labs for warfarin

A

Baseline: PT/INR, aPTT, CBC, creatinine, LFTS, pregnancy test

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4
Q

Factors to determine anticoagulation therapy

A

Initial vs long term agent, route, renal function, antidote, contraindications (pregnancy or risk of hemorrhage grater than benefit), cost, duration, compliance etc

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5
Q

Labs needed for pt on LMWH

A

Baseline: aPTT, PT/INR, CBC, creatinine
Monitoring: none really, anti-factor Xa activity testing if required
Usually pt weight based

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6
Q

Reversal agents for direct thrombin inhibitors

A

Idarucizumab for Dabigatran but others is just supportive care for non-life threatening bleeding

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7
Q

What is another name for hemolytic uremia syndrome?

A

Shiga-toxin mediated HUS

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8
Q

Types of anticoagulants

A 
UFH
LMWH
Warfarin (vitamin K agonist)
Factor Xa inhibitors
Oral direction thrombin inhibitors
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9
Q

Labs needed for a pt on UFH

A

Baseline: aPTT, PT/INR
Monitoring: aPTT or factor Xa

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10
Q

Primary hypercoagulable disorders

A

Antithrombin or protein c/s deficiencies, factor V leiden and prothrombin gene mutations

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11
Q 
Target INR by condition:
Prophylaxis
VTE
Afib
Mitral mechanical valve
Aortic mechanical valve
A 
1.5-2
2-3
2-3
2.5-3.5
2-3
< means blood is too thick and more then it means risk of bleeding
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12
Q

Platelet disorders

A

Platelet dysfunction, splenic sequestration, increased destruction, impaired production

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13
Q

What does warfarin do?

A

Inhibits conversion of vitamin K to active form which depletes vitamin K dependent clotting factors and inhibits protein C (inhibits propagation but does not remove thrombus)

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14
Q

Reversal agent for UFH/LMWH

A

Protamine

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15
Q

What is thrombotic thrombocytopenic purpura?

A

Medical emergency
Seen in females and blacks
Either acquired (autoantibodies directed against ADAMTS-13 like in pregnancy) or inherited ADAMTS-13 mutations
Microthrombi are formed throughout the body

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16
Q

PPT or aPTT

A

Evaluates intrinsic and common pathways

Monitor UFH therapy

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17
Q

Monitoring for warfarin therapy

A

Titrate dose to appropriate INR
Monitor INR frequently (daily and then weekly then every 2-4 wks)
Fun fact: vitamin K will decrease INR

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18
Q

What is overlap therapy with warfarin?

A

Parental therapy (UFH/LMWH/fondaparinux) should overlap with warfarin for at least 5 days and until INR is therapeutic for minimum of 24 hrs or 2 days

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19
Q

Tx for thrombotic microangiopathy

A

Plasma exchange, supportive care (especially for diarrhea associated HUS)

20
Q

When do you always give anticoagulation?

A

Mechanical heart valves
Afib
VTE

21
Q

What occurs in splenic sequestration?

A

Splenomegaly or hypersplenism due to spleen eating up platelets that leads to thrombocytopenia
Ex: vascular congestion from cirrhosis

22
Q

What lab findings might be seen in thrombotic microangiopathy?

A

Hemolytic anemia (fragmented RBCs/schistocytes, increased LDH, increased indirect bilirubin, decreased serum haptoglobin, negative Coombs), thrombocytopenia, normal PT and aPTT, AKI

23
Q

What happens when someone has a supratherapeutic INR?

A

Depends on reasoning whether too much Coumadin or bleeding

But there are reversal agents (vitamin K, fresh frozen plasma, prothrombin complex concentrate)

24
Q

PT

A

Evaluates extrinsic and common pathways

Monitor warfarin therapy

25
Q

What is in the hypercoagulable panel?

A

Antithrombin, factor V leiden, protein C/S, prothrombin gene mutation, lupus anticoagulant (anti phospholipid antibodies), MTHFR gene (recurrent miscarriages)

26
Q

When is HUS seen?

A

Mostly in kids due to shiga toxin producing E. Coli (O157:H7) found in stool culture
Most have recent or current diarrheal illness

27
Q

Drugs that interact with warfarin

A

Acetaminophen, ASA, cephalosporins, cipro, diclofenac, macrolides, sulfas, contraceptives (all increase except this decreases effect)

28
Q

Reasons for increased destruction of platelets

A 
Immune thrombocytopenia (ITP)
Disseminated intravascular coagulation
Heparin induce thrombocytopenia (HIT)
Thrombotic microangiopathies (TMA)- TTP or HUS
29
Q

What is the pentad of TTP?

A 
Microangiopathic hemolytic anemia
Thrombocytopenia
Acute kidney injury (uncommon)
Neurological deficits
Fever
(might also see purpura/petechiae, pallor, jaundice)
30
Q

International normalized ratio

A

More accurate reflection of PT calculated as ratio of patients PT to control PT
Normal is 1
Increased with warfarin use

31
Q

INR 4.5-10 and no evidence of bleeding

A

Don’t use vitamin K, just hold the coumadin

32
Q

Platelet dysfunction

A

Can either be acquired or congenital
Acquired: drugs, uremia, liver disease, von Willebrand disease, myeloproliferative disease
Treat underlying cause or platelet transfusion

33
Q

Other coagulation tests

A

Inhibitor screen (mixing test)
Thrombin time
Fibrinogen (low levels result in impaired clot formation)
D-dimer

34
Q

Reversal agents for direct Xa inhibitors

A

Supportive care for non-life threatening bleeding

35
Q

DOACs (direct oral anticoagulants)

A

Rivaroxaban, Apixaban, Edoxaban (factor Xa-i), Dabigatran (oral direct thrombin-i)

36
Q

Vitamin K assocaited major bleeding

A

Rapid reversal of AC with PCC rather than plasma (also give vitamin k 5-10 mg iv)

37
Q

INR > 10 and no evidence of bleeding

A

PO vitamin K

38
Q

Reasons to use warfarin

A

Prophylaxis/tx of VTE, inherited thrombophilia, afib, prosthetic heart valve, stroke

39
Q

Guidelines for anticoagulation therapy

A

For pts with DVT of leg or PE and no cancer, DOACs are recommended over warfarin (which is over LMWH)

40
Q

Triad for hemolytic uremic syndrome

A

Microangiopathic hemolytic anemia
Thrombocytopenia
Acute kidney injury

41
Q

What options are possible for oral long term anticoagulation?

A

Factor Xa inhibitors, direct thrombin inhibitors or warfarin

42
Q

What dosing to start Warfarin?

A

Don’t use a loading dose (hemorrhages and doesn’t offer rapid protection)
Should be started on day 1/2 of heparin therapy and initial dose of 5 mg/day

43
Q

Reasons for impaired production of platelets

A

Congenital/acquired bone marrow failure, chemo/radiation, bone marrow infiltration, nutritional deficiencies or alcohol

44
Q

Contraindications for LMWH

A

Impaired kidney function

45
Q

What characterizes thrombotic microangiopathy?

A

Thrombocytopenia due to incorporation of platelets into thrombi in microvasculature and microangiopathic hemolytic anemia

X Clin Lab Med (4 decks)

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