Acquired Blood dys Flashcards
what 3 things are required for clotting
platelets, vessel wall, clotting factors
what happens to clotting in massive blood loss
RBC’s can’t push platelets to vessel wall so they can’t adhere
describe what PT measures in clotting
prothrombin time - measures factors 2, 5, 7, 10 and fibrinogen which is the extrinsic pathway
time in seconds from exposure to clot formation
what is the only test that measures factor VII
prothrombin time
what are causes of prolonged PT test
deficiency in 2, 5, 7, 10 or fibrinogen (vit K deficiency) - they are on warfarin or have liver disease
what clotting tests give evidence of early liver disease
isolated prolonged PT but normal APTT
which clotting factor has the shortest half life
VII
what is an APTT and what does is measure
activated partial thromboplastin time
measure 2, 5, 8, 9, 10, 12, kallikrein, HMWK and fibrinogen
what can make a APTT test be abnormal without having bleeding problems
deficiencies in kallikrein, HMWK and factor 12
what can cause isolated APTT
UFH, lupus anticoagulant, haemophilia or deficiencies sin APTT clotting factors
what are common things that cause prolonged PT and APTT
deficiency in 2, 5, 10 or fibrinogen, DIC, HMWK, kallikrein deficiency
what does the thrombin time TT measure
function and amount of function of fibrinogen
what causes prolonged TT
dysfibrinogenaemia - none
low fibrinogen
heparin
DIC
what is LAC in coagulation
lupus anticoagulant - IgG/M autoantibody which prolongs the APTT
what type of drug is heparin
anticoagulant
what is the mode of action of heparin and its subtypes
wraps around antithrombin - inhibits factor X
LMWH - inhibits factor Xa
UFH - inhibits Xa and thrombin to switch of coagulation cascade