Clotting Screen Flashcards
What is testing in a clotting screen?
PT INR APTT Thrombin time Fibrinogen
What is PT?
Prothrombin time
What is the normal PT?
10-14 seconds
What does PT measure?
Time taken for the blood to clot via the extrinsic pathway
What is INR?
International normalised ration
Standardised version of PT
What is the normal INR?
0.8-1.2
What is APTT?
Activated partial thromboplastin time
What is the normal APTT?
25-35 seconds
What does APTT measure?
Time taken for blood clot via the intrinsic pathway
What does thrombin time measure?
How fast fibrinogen is converted to fibrin by thrombin
What is the normal thrombin time?
10-15 seconds
What is the normal fibrinogen level?
200-400 mg/dL
What can cause chronic low fibrinogen levels?
Liver disease
Malnutrition
What can cause acute low fibrinogen levels?
DIC
Large blood transfusions
What can cause physiological high fibrinogen levels?
Pregnancy
Oral contraceptives
HRT
What can cause pathological high fibrinogen levels?
Acute infections Coronary heart disease MI Inflammatory disorders Stroke Trauma
What can cause a prolonged PT with a normal APTT?
Liver disease
Low vit K
Low/defective factor VII
What can cause a normal PT with a prolonged APTT?
Low/defective
- factor VIII
- factor IX
- factor XI
- factor XII
Von Willebrand disease
Lupus anticoagulant
What can cause a prolonged PT and prolonged APTT?
Low/defective
- factor I
- factor II
- factor V
- factor X
Liver disease
DIC
What can cause a normal PT and APTT with a bleeding/clotting disorder?
Low platelet function
Thrombocytopenia
Factor XIII deficiency
