Plasma sex steroid and gonadotrophin patterns in human menstrual cycles.

Sensitive and specific displacement analysis methods for the assay of steroid hormones in small volumes of plasma are described. Plasma sex steroid and gonadotrophin hormone patterns were determined throughout a number of normal menstrual cycles. The mean cycles showed patterns which were similar to those described by other workers. However, examination of individual cycles provided information which may contribute to our understanding of menstrual cycle regulation with particular reference to the pattern of 17alpha-hydroxyprogesterone and steroid-gonadotrophin interactions.