A doctor will test for prolactin blood levels in women with unexplained milk secretion (galactorrhea), or irregular or absent menses or infertility, and in men with impaired sexual function. Thyroid function tests will be drawn and a history obtained to include other conditions and medications known to raise prolactin secretion. In a woman with amenorrhea, a routine pregnancy test should be performed, as prolactin levels are routinely elevated in pregnancy.
Then, a MRI scan will be performed to detect the presence of a pituitary tumor and determining the size. The MRI scan will also be used to look for effects of the tumor on surrounding tissues. Other tests include assessment of production of other pituitary hormones, to insure they are normal. Depending on the size of the tumor, an eye exam with measurement of visual fields (to detect loss of peripheral vision) may be performed.