[Changes in the gonadotrophins, in the prolactin and in the sexual steroid levels throughout the normal menstrual cycle (author's transl)].

The authors describe the hormone changes that occur in a normal woman throughout the menstrual cycle. These is no circadian rhythm in the release of gonadotrophins after puberty. LH is liberated in a pulsatile way throughout the day and the periodicity and amplitude of the episodes vary throughout the cycle with a notable peak of this hormone before ovulation. The level of FSH is greater early in the follicular phase and in mid-cycle, where there is also a cycle together with that of the LH. In spite of these variations a single estimation of gonadotrophins does represents their secretion over 24 hours. The changes in total and free oestradiol and in oestrone are parallel. There are two maxima, the one being preovulatory and preceding the gonadotrophin peak and the other throughout the whole luteal phase. Progesterone changes little throughout the day. It is low during the follicular phase and gradually starts to rise before the preovulatory peak of gonadotrophins, and stays raised throughout the whole luteal phase, following during this phase a variable curve. The 17 hydroxyprogesterone is similarly low in the follicular phase. Its cycle peak is stronger and its rise in the luteal phase weaker than that of progesterone. The secretion of androgens is marked by changes throughout the day of a circadian nature (maximal for dehydroepiandrosterone and delta 5 androstenediol) and cyclic (especially for androstenediol which rises in mid-cycle). Prolactin secretion is marked by changes throughout the day, circadian (maximum during the night) and cyclical (minimum follicular, maximum preovulatory, with a luteal level higher than the follicular level). These changes should be considered in order to work out correctly the levels of hormones that should be prescribed on the precise dates and worked out in accordance with the date of menstruation and temperature curve taken throughout the cycle.