We investigated sensitivity to activated protein C (APC) in 43 men, 42 women not using oral contraceptives (OC) and 38 women using OC containing 30.0-37.5 micrograms ethinyl estradiol. A commercially available kit was used. Men were more sensitive to APC as compared with women not using OC (p < 0.005), but this difference seems not to be of clinical importance. Women using OC showed to be significantly less sensitive to APC, reflected by a lower APC-ratio, as compared with men (p < 0.005) and women not using OC (p < 0.05). So, in normal individuals the APC-sensitivity differs according to sex and estrogen intake. This should be taken into account when interpreting APC-ratios.
PIP: The authors investigated sensitivity to activated protein C (APC) in 43 men, 42 women not using oral contraceptives (OCs), and 38 women using OCs containing 30.0-37.5 mcg ethinyl estradiol. A commercially available kit was used. Men were more sensitive to APC as compared with women not using OCs (p 0.005), but this difference seems not to be of clinical importance. Women using OCs were found to be significantly less sensitive to APC, reflected by a lower APC ratio, as compared with men (p 0.005) and women not using OCs (p 0.05). So, in normal individuals the APC sensitivity differs according to sex and estrogen intake. This should be taken into account when interpreting APC ratios.