Oral contraceptives and endocrine changes.

In groups of women taking oral contraceptives and in control groups of women, the serum levels of cortisol, protein-bound iodine, and total thyroxine were measured together with the T(3) binding index. The daily excretion in the urine of free cortisol, 17-hydroxycorticosteroids, 17-ketosteroids, pregnanediol, pregnanetriol, total oestrogens, total catecholamines, and 4-hydroxy-3-methoxymandelic acid was also assayed. The frequency distribution of the values obtained indicates that oral contraceptives have a marked influence on the endocrine environment. The smallest deviations were observed in urinary excretion of total catecholamines and of 4-hydroxy-3-methoxymandelic acid. In some individuals the hormone assays were continued throughout the menstrual cycle. The morning and afternoon levels of serum cortisol tended to increase during the period when the oral contraceptive was being taken.