Response to Letter by Inoue et al
Thank you for your interesting comment and for sharing your experiences regarding hormone replacement therapy (HRT) effects on protein C and S levels in women with stroke. Although case reports from your practice and other larger studies cited in our article1 support the notion that protein C and S levels may be lowered in women using HRT at the time of stroke, this conclusion is somewhat confounded by the timing of the blood draws for these coagulation proteins. Both proteins C and S are lowered in the acute phase of thrombosis,2,3 inflammation or in an acute illness requiring hospitalization.4 Therefore, was the apparent deficiency of protein C and S from the acute phase of the stroke or from the HRT? As we discussed in the Advancing the Study of Women Conference proceedings,1 HRT may have a mild to moderate prothrombotic effect on hemostasis, but whether this is the cause of ischemic stroke in the majority of women remains uncertain.
Bushnell CD, Hurn PD, Colton C, Miller VM, del Zoppo G, Elkind M, Stern BJ, Herrington D, Ford Lynch G, Gorelick P, James A, Brown C, Choi E, Bray PF, Newby LK, Goldstein LB, Simpkins J. Advancing the study of stroke in women: summary and recommendations for future research from an NINDS-sponsored multidisciplinary working group. Stroke. 2006; 37: 2387–2399.
Mayer SA, Sacco RL, Hurlet-Jensen A, Shi T, Mohr JP. Free protein S deficiency in acute ischemic stroke: a case-control study. Stroke. 1993; 24: 224–227.