Oral contraceptives and the dexamethasone suppression test

Among other confounding factors, the influence of the intake of estrogen-containing oral contraceptives on the dexamethasone suppression test (DST) results has never been specifically studied. Therefore, we performed 1 mg DSTs in 14 healthy women taking oral contraceptives and 14 age-matched women taking no oral contraceptives. Mean 0800h basal total cortisol was significantly higher among the women taking contraceptives than in the control group, whereas mean free cortisol did not significantly differ. At 1600h following DST, no significant difference existed between the two groups. Two subjects taking contraceptives and one control subject were considered DST nonsuppressors. These results confirm the powerful influence of oral contraceptives on basal total cortisol levels but suggest a lack of significant influence on DST results.