Differential effects of oral and transdermal estrogen/progesterone regimens on sensitivity to activated protein C among postmenopausal women: a randomized trial.
OBJECTIVE
Activated protein C (APC) resistance not related to the factor V Leiden mutation is a risk factor for venous thrombosis. Oral estrogen replacement therapy (ERT) has been reported to induce APC resistance. Little is known about the effect of transdermal estrogen.


RESULTS
We enrolled 196 postmenopausal women who were randomly allocated to receive either 1 mg 17beta-estradiol orally (n=63) or 50 microg 17beta-estradiol transdermally per day (n=68), both associated with 100 mg progesterone daily or placebo (n=65) for 6 months. An activated partial thromboplastin time (APTT)-based test and the effect of APC on thrombin potential (ETP) were used. Oral ERT induced an ETP-based APC resistance compared with both placebo (P=0.006) and transdermal ERT (P<0.001), but there was no significant effect of transdermal ERT compared with placebo (P=0.191). There was no significant effect of ERT on the APTT-based APC sensitivity ratio. Prothrombin fragment 1+2 plasma levels were significantly higher after 6 months of treatment in women allocated to oral ERT compared with those on placebo and transdermal ERT and were positively and significantly correlated with changes in ETP-based APC sensitivity ratio.


CONCLUSIONS
Our data show that oral, unlike transdermal, estrogen induces APC resistance and activates blood coagulation. These results emphasize the importance of the route of estrogen administration.
Oger
Emmanuel
E
Département de Médecine Interne, Hôpital de la Cavale Blanche, Brest, France. emmanual.oger@southernhealth.org.au
Alhenc-Gelas
Martine
M
Lacut
Karine
K
Blouch
Marie-Thérèse
MT
Roudaut
Nathalie
N
Kerlan
Véronique
V
Collet
Michel
M
Abgrall
Jean-François
JF
Aiach
Martine
M
Scarabin
Pierre-Yves
PY
Mottier
Dominique
D
D000279:Administration, Cutaneous; D000284:Administration, Oral; D004967:Estrogens / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D017698:Postmenopause / Q000502:physiology*; D011374:Progesterone / Q000008:administration & dosage* / Q000627:therapeutic use; D011486:Protein C / Q000378:metabolism*
D004967:Estrogens; D011486:Protein C; D011374:Progesterone