Sunday, March 31, 2019

Protein C and warfarin, tests and Factor V Leiden mutation

warfarin decreases protein C level, so can't measure it if they are on warfarin

Activated protein C resistance is SCREENING TOOL  for Factor V Leiden mutation
APCR is also caused by: pregnancy, contraceptives, cancer, APL's,  so its sensitive but not specific for Factor V Leiden mutation.  APCR is NOT associated with protein C deficiency or AT 3 deficiency.

Factor V causes a 2-10 x risk of lifetime clots, venous not arterial.  High in Europeans, lower in Asians and African Americans. Its AUT DOMINANT. Anticoagulate if present and multiple events or if one severe event. PT G20210A gene mutation also confers only a venous risk.  Additive risk with contraceptives and with each other

Warfarin also causes a rapid fall in Factor VII (extrinsic pathway). Heparin decreases skin necrosis

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