When the follicle matures and reaches 8–10 mm in diameter it starts to secrete significant amounts of estradiol . Normally in humans only one follicle becomes dominant and survives to grow to 18–30 mm in size and ovulate, the remaining follicles in the cohort undergo atresia. The sharp increase in estradiol production by the dominant follicle (possibly along with a decrease in gonadotrophin surge-attenuating factor) cause a positive effect on the hypothalamus and pituitary and rapid GnRH pulses occur and an LH surge results.
Hormone levels may be drawn and evaluated before therapy is started. This may include an FSH, estradiol, and testosterone (free and total) for women. Men need a PSA (prostate specific antigen), estradiol, testosterone, and blood count prior to starting therapy. Thyroid hormone levels (TSH) may also be evaluated. In men, follow up levels, including a PSA, blood count and estradiol, may be obtained prior to some of the subsequent testosterone implantation. Men are encouraged to notify their primary care physician and obtain a digital rectal exam each year. Women are advised to continue their monthly self-breast exam and obtain a mammogram and/or pap smear as advised by their gynecologist or primary care physician.