Special Coagulation Testing
Card Set Information
Special Coagulation Testing
Hematology exam two
What is Heparin?
An acidic unfractionized mucopolysaccharide that inhibits blood coagulation potentiating the action of Antithrombin
How is heparin given to a patient?
Must be given by injection
Where is heparin inactivated in the body, how is it excreted, and what is its half life?
Inactivated by the liver and excreted in the urineHalf life of one hour
How does heparin work as an anticoagulant?
Enhances complexes between Antithrombin and activated serine proteases:
Thrombin IIa, IXa, Xa, and XIa
These complexes inactivate these serine protease factors
List 5 points of
1. Continuous intravenous infusion
2. Best for surgical patients or pregnancy
3. High molecular weight 30,000-40,000 units
4. Maintains a therapeutic anticoagulationMeasured by APTT
List 5 points about
Low Molecular Weight heparin
1. LMWH is given as a subcutaneous injection
2. Longer half life than HMWH
3. Usually given once a day as a prophylaxis
4. Given as outpatient therapy as treatment for DVT
5. Reduces the risk of heparin-induced thrombocytopenia
Why should a heparin IV be stopped immediately after a bleeding episode occurs?
Heparin has an anti-platelet function.
What should you do if bleeding occurs following a subcutaneous injection of heparin?
Protamine sulfate is given to inactivate heparin.
Give 1mg of protamine for every 100 units of heparin
What is a side effect of heparin administration that occurs within the first 24 hrs. Why?
* Mild lowering of platelets occurs in the first 24 hours of heparin administration
*Usually due to platelet clumping
*Heparin binds to
platelet factor 4
following the generation of an
antibody against heparin
*Antibody of the heparin-Platelet 4 complex leads to
platelet activation, thrombocytopenia, and thrombosis
What is warfarin aka Coumarin or Coumadin?
1. oral anticoagulant
vit k antagonist
so decreases activity of factors II, VII, IX, and X
3. VII levels fall considerably w/in 24 hrs
How long does it take warfarin to reach its full anticoagulant effect? Why?
days for full anticoagulant effect due to plasma half life of
Describe the administration of an oral anticoagulant.
*10 mg on day one, 5 mg on day two, 5 mg on day three, followed by PT monitoring
*Adjustments should be made according to the PT result.
*Maintenance dose ranges from 3-9 mg per day.
*Lower loading dose is recommended for elderly patients
What control tests strongly evaluate the therapeutic response to oral anticoagulation? What are the ranges for the tests?
*Patients in recovery from DVT,
should have a INR range from
2.0 to 3.0
mechanical heart valves
should have a therapeutic range from
2.5 – 3.5
What is Antiphospholipid Syndrome (APS)?
1. Persistence of an antiphospholipid antibody
2. Usually directed against
– Detected in patients with SLE
4. Associated with venous and arterial
When is APS usually seen, what is it associated with, and how is it treated?
1. Usually seen after a lymphoproliferative disorder, post-viral infections
2. Associated with arterial thrombosis (stroke and myocardial infractions), Placental infarctions, and abortions
3. Treat with oral anticoagulants and maintain an INR greater than 2.0