Flashcards in Lecture 3 - Acquired Blood disorders Deck (27):
What is prothrombin time?
Measures external coagulation pathway.
When you get a break in vessel wall - tissue factor released .
Binds to factor 7
What does prothrombin time measure?
Factors 2, 5, 7, 10
What causes prolonged prothrombin time?
o Deficiency/ inhibition of one of the factors
o Liver disease
o Vit K deficiency (caused by haemorrhage in newborn/ obstructive jaundice)
o Blood transfusion causes dilution of clotting factors
o Over-heparinisation (too much heparin in sysem)/ some lupus anticoagulants
What does activated partial thromboplastin time measure?
Factors 2, 5, 9, 10, 12, 13, HMWK
What causes prolonged APTT?
o Deficiency of one of the factors
o Liver disease
o Vitamin K
o Heparin (unfractionated)
o Lupus anticoagulant
What causes prolonged PT and APTT?
o Deficiency of 2, 5, 10, fibrinogen
o Vitamin K deficiency
o Liver failure
If it's just Prothrombin time raised --> early signs of disease.
What does thrombin time measure?
What causes prolonged thrombin time?
What to look for in a clinical examination of a possible bleeding disorder?
Signs of underlying disease (joints/ muscles/ skin)
Measure fibrinogen + D-Dimer
Give examples of anticoagulants?
How does heparin work?
Wraps around thrombin + factor 10a - switches off clotting cascade
LMWH - mostly inhibits factor 10 a
What's the difference between LMWH and UH
LMWH has a higher bioavailability + longer half life, so you don't need to routinely monitor.
What are the side effects of heparin?
How to reverse heparin overdose?
How does warfarin work?
Inhibit vitamin K uptake.
Affects factors 10, 9, 7, 2
What is INR?
Prothrombin ratio - Allows you to control anticoagulant dose.
How to treat warfarin overdose?
Give prothrombin complex concentrate
What are DOACs?
How do they work?
Inhibits factor 10a: Rivaroxaban, Apixaban, Edoxaban
Inhibits thrombin - Factor 1a, Dabigatran
How does fondaparinux work?
Indirectly inhibits 10a
What are the symptoms of bleeding in renal disease patients?
excessive bleeding from venepuncture
Uncontrolled high BP + on dialysis incr risk of ICH
How to prevent bleeding in renal disease patients?
What is DIC?
Disseminated intravascular coagulation - small clots block small vessels.
Causes ischaemia --> organ damage --> bleeding
What causes acute DIC?
Tissue necrosis/ trauma
Massive blood loss
What causes chronic DIC?
Cancer/ eng stage liver disease
How to diagnose DIC?
Order platelet count, PT, fibrinogen, D-Dimer.
Score each test. If >=5 DIC
What are the clinical features of IDC
Bleeding for surgical wounds
Multiple organi failure