Several important peptide hormones are secreted from the pituitary gland. The anterior pituitary secretes three hormones: prolactin , which acts on the mammary gland ; adrenocorticotropic hormone (ACTH), which acts on the adrenal cortex to regulate the secretion of glucocorticoids ; and growth hormone , which acts on bone , muscle , and the liver . The posterior pituitary gland secretes antidiuretic hormone , also called vasopressin, and oxytocin . Peptide hormones are produced by many different organs and tissues, however, including the heart ( atrial-natriuretic peptide (ANP) or atrial natriuretic factor (ANF)) and pancreas ( glucagon , insulin and somatostatin ), the gastrointestinal tract ( cholecystokinin , gastrin ), and adipose tissue stores ( leptin ).  
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.