Contraceptive options for women with factor V Leiden [letter]

I read with interest the article by Lynette Ament CNM PhD published in the January/February issue of the Journal; however it is erroneously stated that activated protein C degrades coagulation factors V and VII. The protein C- protein S system among other functions cleaves coagulation factors Va and VIIIa and renders them inactive (Editors note: See Erratum in the March/April 2004 Vol. 49 No. 2 issue). This is accomplished by cleavage of the arginine residues 506 and 306 of factor Va as well as 336 and 562 of factor VIIIa. In addition there is evidence of a permissive effect of factor V on protein C- mediated cleavage of factor VIIIa. This effect is abrogated by the presence of the factor V Leiden mutation. The author does not comment on the use of intrauterine devices as an alternate contraceptive method. This is a safe method that effectively prevents pregnancy and it should be considered along with barrier methods for child-bearing-age female patients with a thrombophilic mutation. It also should be stated that use of oral contraceptives containing a third-generation progestogen confers a 50-fold increase in the risk of venous thromboembolism in women bearing the Leiden mutation thus the use of these agents should be avoided in this group of patients. (excerpt)