Early and late hormonal changes following progesterone injection to patients with secondary amenorrhea

In humans, progesterone (Po) administration has been shown capable of eliciting luteinizing hormone (LH) and prolactin surges in a good estrogenic milieu, but whether such changes induce corpus luteum function still remains controversial. We therefore proposed to explore further the second hypothesis in a placebo-controlled type of study. In patients with secondary amenorrhea and low circulating estradiol (E2) levels with or without ovaries, a 50-mg progesterone injection induced only a short and transient rise in plasma Po levels. On the other hand, a similar injection to patients with mid-to late follicular levels of circulating E2 and intact ovaries induced a surge of plasma LH and prolactin which was followed by a sustained elevation in plasma Po. Furthermore, a rise in basal body temperature accompanied by evidence of secretory endometrium was also observed in these patients. It is concluded that, in a proper endocrine milieu, progesterone administration may induce luteinization in human subjects.