Your doctor will review your symptoms, medical history and current medications. This information is very important because certain medical conditions and/or prescription drugs can have significant effects on your levels of body hormones. For example, psychiatric drugs called neuroleptics can increase blood levels of prolactin, and prescription glucocorticoids (even therapeutic injections of dexamethasone — Decadron and other brand names — into injured joints) can cause high blood levels of glucocorticoids.
During a physical examination, your doctor will look for the signs that show your body is overproducing a particular pituitary hormone. For example, your doctor may look for breast milk production caused by a prolactin-producing tumor or a moon-shaped face and abdominal marks caused by an ACTH-producing tumor.
If your doctor suspects that you have a pituitary tumor, the first step usually is a blood test for hormone levels. Your doctor probably will order an MRI scan of your head to obtain detailed images of the pituitary gland. Usually this test involves an injection of a dye called gadolinium, which is used to highlight brain structures.
If you are having any visual symptoms or the MRI shows a large pituitary tumor, your doctor will refer you to an eye specialist (ophthalmologist) for a comprehensive eye exam, including special eye tests that detect visual loss in specific visual fields.