EFFECTS OF SUB-50 ORAL-CONTRACEPTIVES ON HOMOCYSTEINE METABOLISM - A PRELIMINARY-STUDY

The influence of a monophasic sub-50 oral contraceptive (OC), Marvelon(R), on fasting total homocysteine levels was investigated in OC users and controls. Homocysteine levels in serum of OC users were significantly higher (P < .01) than in controls during the low-hormonal phase of the cycles and comparable with levels determined in heterozygotes for homocystinuria. Blood levels of pyridoxal phosphate (PLP) were significantly lower (P < .05) in OC users both in the low and high hormonal phase. However, there were no significant differences in the levels of homocysteine nor in folate and vitamin B12 between both groups in the high-hormonal phase. In contrast to the control group, the homocysteine levels in OC users in the high-hormonal phase of the cycle were significantly decreased compared with those on a low-hormonal day (P < .05). These data suggest that cyclically recurrent periods of hyperhomocysteinemia do occur during sub-50 OC use in normal women and might be considered a predisposition to the occurrence of vascular complications.