If the oestrogen goes up the FSH and LH go down and vice versa. It is important to remember that oestrogen is formed in the follicle (see The Normal Ovary). FSH is a abbeviation of follicle stimulating hormone and LH of luteinsing hormone. It is necessary for the formation of the yellow body the CORPUS LUTEUM. Both FSH and LH are necessary for the normal development of the follicle and ovulation. It is also important that their levels are regulated by the negative feedback effect of oestrogen within certain limits.
Following ovulation , the corpus luteum appears . It has a limited live span and LH plays a posible role in its function. Normal LH levels levels won't be able to expand this live span beyond ten days.
In the condition known as polycystic ovarian syndrome (PCO) the LH levels are usually increased.
After the menopause the ovaries ceased to produce oestrogen and the FSH and LH levels become very high in an effort to stimulate the non responding ovaries (see MENOPAUSE).
The pituitary also produces another important hormone called PROLACTIN. One of prolactin's most important functions is stimulating the breasts to produce milk. Excessive prolactin production in non lactating women causes ovarian dysfunction with anovulation ( the ovary stops producing egg cells).