Exam 1: Coagulation Studies Flashcards by Katie Seils

What causes acquired platelet dysfunction?

Drugs, uremia, liver disease, VWD, and myeloproliferative disease

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What is the treatment for platelet dysfunction?

Treatment of the underlying cause and platelet transfusion

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What happens in splenic sequestration?

The spleen takes in the platelets and destroys them

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What are the disorders that cause increased destruction of platelets?

Immune thrombocytopenia (ITP). Disseminated Intravascular Coagulation (DIC), Heparin induced thrombocytopenia (HIT), and thrombotic microangiopathies

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What are the two types of thrombotic microangiopathies?

Thrombotic Thrombocytopenic purpura (TTP) and hemolytic uremic syndrome

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What is Heparin induced thrombocytopenia?

New-onset thrombocytopenia while on heparin therapy
-Anti-platelet antibodies cause platelet activation, which increases risk of venous and arterial thrombosis, eventually leading to thrombocytopenia and prothrombotic states

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What are thrombotic microangiopathies?

Characterized by thrombocytopenia due to the incorporation of platelets into thrombi in the micro vasculature and microangiopathic hemolytic anemia

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What is microangiopathic hemolytic anemia?

Mechanical shearing of RBCs as they pass through platelet-rich micro thrombi in the microvasculature

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What is the difference between acquired and hereditary thrombotic thrombocytopenia purpura?

Acquired is autoantibodies directed against ADAMTS-13 and hereditary is inherited ADAMTS-13 mutations

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What is TTP?

A medical emergency of micro thrombi formed throughout the body

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What is the Pentad of TTP?

Microangiopathic hemolytic anemia, thrombocytopenia, AKI, neurological deficits, and fever

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What is hemolytic uremic syndrome?

Shiga toxin-mediated HUS

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What is the etiology of HUS?

Shiga toxin producing E. Coli and most have a recent or current diarrheal illness, often hemorrhagic

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What is the triad of HUS?

Microangiopathic hemolytic anemia, thrombocytopenia, and AKI

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What will be seen on lab work for thrombotic microangiopathies?

-Microangiopathic hemolytic anemia, thrombocytopenia, PT and aPTT are normal, and AKI

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How is Microangiopathic hemolytic anemia seen on lab work?

Fragmented RBCs (shistocytes), increased LDH, increased indirect bili, decreased serum haptoglobin, and negative Coombs test.

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What is the treatment for thrombotic microangiopathies?

Plasma exchange and supportive care

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What conditions can cause impaired production of platelets?

Congenital bone marrow failure, acquired bone marrow failure, exposure to chemo or radiation, bone marrow infiltration, and nutritional deficiencies

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What are the coagulation studies?

PTT or aPPT, anti Xa, and PT/INR

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What is PTT or aPTT used to measure?

Evaluate the intrinsic and common pathways and used to monitor unfractionated heparin therapy

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What is anti-factor Xa used to monitor?

Monitors unfractionated heparin and LMWH/Lovenox therapy, preferred over PTT and aPTT

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What does PT measure?

Evaluates the extrinsic and common pathways and used to monitor warfarin/Coumadin therapy

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What is INR?

A more accurate reflection of PT, calculated as a ratio of the patients PT to a control PT.
-Used to monitor warfarin/Coumadin therapy

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What is inhibitor screen?

Coagulation factor deficiency vs inhibitor protein

What is thrombin time?

Measures the final step of coagulation, the conversion of fibrinogen to fibrin. -Not used as an initial screen

What can the fibrinogen lab test indicate?

Low levels can result in impaired clot formation and increased bleeding risk

What are the components of the hypercoagulable panel?

- Antithombin - factor V-Leiden - Protein C - Protein S - Prothombin gene mutation - Lupus anticoagulant - MTHFR gene

What are the 2 classes of Direct Oral Anticoagulants?

Factor Xa and Oral direct thrombin inhibitors

What are the 4 Factor Xa inhibitors?

Fonduparinux, Rivaroxaban, Apixiban, and edoxaban

What kind of drug is Dabigatran?

Direct oral thrombin inhibitor

Which anticoagulants have to follow 5-10 days of parental anticoagulation?

Dabigatran and Edoxaban

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

DOAC are recommended over Warfarin

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

LMWH

What are the baseline labs to obtain if a patient is on UFH?

PT/INR, aPTT, and CBC

What labs are ordered for monitoring UFH?

Factor Xa or aPTT

What are the baseline labs to order if a patient is on LMWH?

PT/INR, aPTT, CBC, and creatinine (you cant use lovenox if creatinine clearance is less than 30)

What labs are used to monitor LMWH?

None, but if required, anti-factor Xa activity testing

What are the baseline labs to order if a patient is on a DOAC?

PT/INR, CBC, and creatinine

What labs are used for monitoring DOAC use?

None, but is required, anti-factor Xa activity testing

What are the baseline labs to order when a patient is put on Warfarin?

PT/INR, aPTT, CBC, creatinine, LFTs

What labs do you order to monitor Warfarin use?

PT/INR

Warfarin should be administered at an initial dose of ****.

5mg/day

Why is a loading dose of Warfarin not recommended?

It may increase hemorrhagic conditions and does not offer rapid protection

What does bridging therapy mean in regards to Warfarin use?

Parenteral therapy of UFH or LMWH should overlap with warfarin for at least 5 days and until the INR is therapeutic for a minimum of 24 hours 2 consecutive days

When starting a patient on Warfarin, how often should you check their INR?

Daily, then weekly. Once stabilized, every 2-4 weeks.

What is the target INR for prophylactic therapy?

1.5-2

What is the target INR for VTE?

2-3

What is the target INR for a fib?

2-3

What is the target INR for mechanical mitral valve? Mechanical aortic valve?

2.5-3.5 2-3

What should you do if your patient has an INR of 4.5-10 and no evidence of bleeding?

Hold warfarin and possibly recommend use of PO vitamin K

What should you do if your patients INR is greater than 10 and has no evidence of bleeding?

Hold warfarin and give PO vitamin K

What should you do if your patient has a Vitamin K antagonist associated major bleeding?

Hold warfarin, rapid reversal of warfarin with PCC, and give IV vitamin K

What is the reversal agent of UFH?

Protamine

What is the reversal agent for LMWH?

Protamine

What is the reversal agent for warfarin?

Vitamin K or 4factor-PCC

What is the reversal agent for Direct thrombin inhibitors?

Idarucizumab, and supportive care for non-life threatening bleeding

What is the reversal agent for Apixiban and Edoxaban?

Andexanet

What is the reversal agent for Rivaroxaban?

Supportive care