Acquired Disorders of Haemostasis Flashcards
What does a mixing test indicate?
Whether an inhibitor is present - 50/50 mixture so prolonged APTT due to this & would otherwise be corrected
Liver disease - what would lab results be?
Low platelet count - portal hypertension and splenomegaly, prolonged PT, APTT and normal TT
DIC - what would lab results be?
Low platelet count, prolonged PT, APTT, grossly prolonged TT
Massive transfusion - what would lab results be?
Low platelet count, prolonged PT, APTT and normal TT
Oral anticoagulants - what would lab results be?
Normal platelet count, grossly prolonged PT, prolonged APTT and normal TT
Heparin - what would lab results be?
Normal platelet count, mildly prolonged PT, prolonged APTT, prolonged TT
Circulating anticoagulant - what would lab results be?
Normal platelet count, normal or prolonged PT, prolonged APTT, normal TT
Vit K deficiency - what would lab results be?
Normal platelet count, prolonged PT, prolonged APTT
Which clotting factors are vitamin K dependant?
2, 7, 9, 10
What is Vit K converted to and by which enzyme?
Vit K hydroquinone by quinone reductase
What is Vit K hydroquinone converted to and by which enzyme?
Vit K epoxide by glutamyl-carboylase
What is converted into Vit K?
Vit K epode by VKOR1
What is the target of warfarin?
VKOR1 and quinone reductase
What is a diagnostic test for Vit K deficiency/for warfarin
PIVKA - defective factor 2, 7, 9, 10 - proteins induced by vit K absence
What are the causes of Vit K deficiency
JDAN
J - jaundice
D - prolonged nutritional deficiency
A- broad spectrum antibiotics - affects gut flora synthesising Vit K
N - neonates ~ 1-7 days - no Vit K in
What is the site of coagulation factors
The hepatocytes EXCEPT F8 - synthesised by reticular epithelial cells/vascular endothelium
As liver disease progresses what happens to APTT,PT,TT
Prolonged APTT, PT, TT
What happens to platelet count with liver disease?
Thrombocytopenia - decreased platelet count due to hypersplenism from portal hypertension
What is a major source or morbidity/mortality in px with liver disease?
Cirrhotic coagulinopathy - increased risk of sever bleeding from invasive procedures/surgery
Haemorrhage - local factors contribute to this e.g. portal hypertension > varicose veins in gullet, oesophageal varies and vatical bleeding worsened if also have coagulopathy/thrombocytopenia
How does liver disease impair haemostasis?
TERPD
T - thrombocytopenia
E - excessive plasmin = activates fibrinolysis
R - reduced plasma/clotting factors
P - platelet dysfunction
D - delayed fibrin polymerisation - altered fibrinogen glucosylation (excess silica acid on fibrinogen molecules)
What is considered to be a massive transfusion?
transfusion volume = px total blood overs in <24 hours if 50% blood volume within 1 hours
Haemostats abnormalities in massive transfusion?
Dilution depletion of platelets and coagulation factors - due to standard pack transfusion (not clotting factors) - * must give FRESH FROZEN PLASMA
What are the dilution effects of haemostasis?
Thrombocytopenia - at least 7-8L in adults usually transfused before problem is likely
Coagulation factor depletion - mainly F5, 8, fibrinogen
DIC common
Citrate toxicity - used as anticoagulant in red cells - uncommon BUT hyperthermia/neomates have increased susceptibility
Hypocalcaemia - from citrates/products transfused - no clinically significant effects on coagulation
What is DIC?
Disseminated intravascular coagulation - a syndrome which occurs due to coagulation triggers - characterised by widespread fibrin deposition in small vessels and reduced platelets and clotting factors = bleeding
Thrombotic manifestation = end organ function, liver dysfunction, renal dysfunction, CNS dysfunction, necrotic skin lesions/ limb necrosis
