Cause:
XI: Genetic, autosomal recessive, incomplete penetrance
IX: Genetic, sex-linked recessive, several types of mutants (Nejm 1970;283:61); or acquired in nephrotics (Ann IM 1970;73:373) and pts w amyloid (binds factor IX) and big spleen, rx w splenectomy (Nejm 1979;301:1050)
Pathophys:Intrinsic system defect (Screening Tests of Clotting Function)
XI: Common in Ashkenazi Jews, 1/190 people have in Israel; rare in others, <1/million
IX: Prevalence = 1/10 000; 16% of all lifelong bleeding diathesis pts
Sx:
XI: Rarely spontaneous bleeding; usually only postsurgery
IX: Severe w trauma, surgery; hemarthroses, hematuria
r/o circulating antibody inhibitors due to SLE, or multiple myeloma
Lab: Hem:Clotting w/u (Screening Tests of Clotting Function)
Rx:Avoid ASA, indomethacin, phenylbutazone, and other NSAIDs.
Refrigerated blood or plasma since both more stable than factor VIII
of IX deficiency: alphanine; danazol 600 mg qd increases endogenous production (Nejm 1983;308:1393); keep levels 5-15% all the time, >40% for surgery