Increased platelet aggregation and decreased high-density lipoprotein cholesterol in women on oral contraceptives.

In vivo platelet function, serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL), and serum triglycerides (TG) were determined in 26 women starting oral contraceptives (OCA). Studies were run prior to, and after one and two months of therapy. Platelet aggregation time decreased by 50 percent or more in eight of the 26 women from a pre-experimental mean value of 387 +/- 136 seconds. TC did not vary but after the women were on medication for two months, HDL decreased from 56 +/- 14.4 mg/dl to 52 +/- 12.3 mg/dl (p less than 0.05). There was a progressive increase in TG under treatment, 74 +/- 23.3 mg/dl on the pre-experimental measurement to 93 +/- 31.0 mg/dl after two months of therapy (p less than 0.005). Women planning to use OCA might best be advised to have aggregation and serum lipid studies done before and early in usage.