Flashcards in Clinical Approach to Bleeding Deck (8):
APTT measures intrinsic pathway of coagulation which includes factors XII, XI, IX, VIII, X, V, II and I; any deficiency, inhibitor or dysfunctional molecule will cause its prolongation.
THROMBIN TIME measures the conversion of fibrinogen to fibrin after the addition of thrombin; any deficiency, inhibitor or dysfunctional molecule of fibrinogen may prolong it. Also heparin inhibits thrombin and prolongs thrombin time.
APTT done on patient plasma mixed with normal plasma to determine if an inhibitor is present. Failure of a previously long APTT to correct after mixing indicates inhibition
Type I vW Disease
This is the most common abnormality. Individuals have a mild to moderate decrease in plasma von Willebrand's factor.
Type II vW Disease
This is much less common. In these cases there are normal or near normal levels of protein--but there are qualitative abnormalities. There are a number of subtypes of type II disease.
Type III vW Disease
These individuals may be either a double heterozygote, or homozygous for a single defect in von Willebrand's factor. These patients have severe mucosal bleeding, no detectable von Willebrand's factor antigen or activity, and may have very little factor VIII.
What are some causes of quantitative platelet disorders?