General Coagulation Notes (Dr. Salazar)

Question 1

What tests are usually run

using the citrated tube (light blue top) ?

Answer 1

• PT, PTT, TT
• fibrinogen
• factor assays
• thrombosis assays
• vWD assays

Question 2

What is the EDTA tube used for ?

Answer 2

• purple top tube
• used for CBC and platelet counts

Question 3

How is the prothrombin time (PT) or

extrinsic pathway set up ?

Answer 3

• 1 part citrated plasma
• 2 parts reagent
  
  • tissue factor, phospholipid, calcium)

Sensitive to:

• 7, 10, 5, 2, and fibrinogen

Question 4

What can cause a prolonged

PT ?

Answer 4

• warfarin therapy or vitamin K deficiency
• liver disease
• acquired or hereditary factor deficiency
• factor or assay inhibitors (drugs, antibodies)

Question 5

What is the activated partial thromboplastin

time (aPTT) sensitive to ?

Answer 5

• 8, 9, 10, 11, 5, 2, fibrinogen, heparin
• called the intrinsic pathway

Question 6

What can cause a prolonged

aPTT ?

Answer 6

.

• Heparin therapy or heparin contamination (IV line)
• Lupus anticoagulant
• Hereditary or acquired deficiency
• Severe liver disease
• factor or assay inhibitors
• Contact system deficiencies
  
  • Not associated with bleeding
  • Factor 12, HMWK, Pre-Kallikrein

Question 7

What is thrombin time a

measure of/sensitive to ?

Answer 7

• Heparin
• Fibrinogen

Question 8

What can cause a prolonged thrombin time ?

Answer 8

• heparin therapy or contamination
• severe fibrinogen degradation (DIC)
• dysfibinogen
• thrombin inhibitor (lepirudin, drugs, antibodies)

Question 9

What can produce increased D-dimer ?

Answer 9

• D-dimer: are fibrin degradation products
• Increased in:
  • thrombosis (DVT, PE, extensive arterial thrombosis)
    
    • quantitative NPV >95% for PE and proximal DVT
  • DIC ( > 8 ug/mL suggests DIC)
  • Thrombolytic therapy

Question 10

What causes an increased

PFA (platelet function analysizer) result?

Answer 10

• thrombocytopenia
• anemia
• antiplatelet drugs
• von Willebrand disease
• other hereditary or acquired platelet dysfunction

Question 11

What can cause decreased

antithrombin activity ?

Answer 11

• Heparin therapy
• ongoing extensive thrombosis
• DIC
• Nephrotic syndrome
• Hereditary deficiency
• asparaginase therapy

Question 12

What causes decreased

protein C activity ?

Answer 12

• warfarin therapy
• vitamin K deficiency
• liver disease
• ongoing extensive thrombosis
• DIC
• hereditary deficiency

Question 13

What can cause a decrease in

free protein S antigen and activity ?

Answer 13

• increased levels of Factor VIII (false low)
• thrombin inhibitors (false high)
• Warfarin therapy
• vitamin K deficiency
• liver disease
• ongoing extensive thrombosis
• DIC
• pregnancy
• Inflammatory syndromes causing an increase in C4b binding protein
• hereditary deficiency

Question 14

What should you suspect if the

PTT and TT are both prolonged ?

Answer 14

• the sample may contain heparin
• or there is a direct thrombin inhibitor
• check the patient drug history

Question 15

What is the differential diagnosis

if the PTT is normal and the PT is prolonged?

Answer 15

• deficiency or inhibitor of factor 7
• early warfarin therapy, factor 7 falls first
• atypical lupus inhibitor

Question 16

What is the differential diagnosis of

prolonged PTT and normal PT ?

Answer 16

• lupus inhibitor
• deficiency or inhibitor of factor 8,9, 11, 12, or contact phase factor

Question 17

What is the differential diagnosis with

prolonged PT and PTT ?

Answer 17

• warfarin therapy
• vitamin K deficiency
• liver disease
• deficiency or inhibitor of factor 2, 5, or 10
• thrombin inhibitor
• fibrinogen deficiency