Coagulation Studies

Question 1

What is microangiopathic hemolytic anemia?

Answer 1

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

Question 2

What is heparin induced thrombocytopenia?

Answer 2

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

Question 3

Labs for warfarin

Answer 3

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

Question 4

Factors to determine anticoagulation therapy

Answer 4

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

Question 5

Labs needed for pt on LMWH

Answer 5

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

Question 6

Reversal agents for direct thrombin inhibitors

Answer 6

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

Question 7

What is another name for hemolytic uremia syndrome?

Answer 7

Shiga-toxin mediated HUS

Question 8

Types of anticoagulants

Answer 8

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

Question 9

Labs needed for a pt on UFH

Answer 9

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

Question 10

Primary hypercoagulable disorders

Answer 10

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

Question 11

Target INR by condition:
Prophylaxis
VTE
Afib
Mitral mechanical valve
Aortic mechanical valve

Answer 11

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

Question 12

Platelet disorders

Answer 12

Platelet dysfunction, splenic sequestration, increased destruction, impaired production

Question 13

What does warfarin do?

Answer 13

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)

Question 14

Reversal agent for UFH/LMWH

Answer 14

Protamine

Question 15

What is thrombotic thrombocytopenic purpura?

Answer 15

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

Question 16

PPT or aPTT

Answer 16

Evaluates intrinsic and common pathways

Monitor UFH therapy

Question 17

Monitoring for warfarin therapy

Answer 17

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

Question 18

What is overlap therapy with warfarin?

Answer 18

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

Question 19

Tx for thrombotic microangiopathy

Answer 19

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

Question 20

When do you always give anticoagulation?

Answer 20

Mechanical heart valves
Afib
VTE

Question 21

What occurs in splenic sequestration?

Answer 21

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

Question 22

What lab findings might be seen in thrombotic microangiopathy?

Answer 22

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

Question 23

What happens when someone has a supratherapeutic INR?

Answer 23

Depends on reasoning whether too much Coumadin or bleeding

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

Question 24

PT

Answer 24

Evaluates extrinsic and common pathways

Monitor warfarin therapy

Question 25

What is in the hypercoagulable panel?

Answer 25

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

Question 26

When is HUS seen?

Answer 26

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

Question 27

Drugs that interact with warfarin

Answer 27

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

Question 28

Reasons for increased destruction of platelets

Answer 28

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

Question 29

What is the pentad of TTP?

Answer 29

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

Question 30

International normalized ratio

Answer 30

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

Question 31

INR 4.5-10 and no evidence of bleeding

Answer 31

Don't use vitamin K, just hold the coumadin

Question 32

Platelet dysfunction

Answer 32

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

Question 33

Other coagulation tests

Answer 33

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

Question 34

Reversal agents for direct Xa inhibitors

Answer 34

Supportive care for non-life threatening bleeding

Question 35

DOACs (direct oral anticoagulants)

Answer 35

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

Question 36

Vitamin K assocaited major bleeding

Answer 36

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

Question 37

INR > 10 and no evidence of bleeding

Answer 37

PO vitamin K

Question 38

Reasons to use warfarin

Answer 38

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

Question 39

Guidelines for anticoagulation therapy

Answer 39

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

Question 40

Triad for hemolytic uremic syndrome

Answer 40

Microangiopathic hemolytic anemia Thrombocytopenia Acute kidney injury

Question 41

What options are possible for oral long term anticoagulation?

Answer 41

Factor Xa inhibitors, direct thrombin inhibitors or warfarin

Question 42

What dosing to start Warfarin?

Answer 42

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

Question 43

Reasons for impaired production of platelets

Answer 43

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

Question 44

Contraindications for LMWH

Answer 44

Impaired kidney function

Question 45

What characterizes thrombotic microangiopathy?

Answer 45

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