One way that it works is to decrease inflammation (swelling). It does this by preventing infection- fighting white blood cells (polymorphonuclear leukocytes) from traveling to the area of swelling in your body. (This is why you are more prone to infection while taking steroids). Taking advantage of the anti-inflammatory properties of the medication, corticosteroids are used to decrease the swelling around tumors. For example, by decreasing swelling around tumors in the spine, brain, or bone, it can decrease the pressure of the tumor on nerve endings and relieve pain or other symptoms caused by the pressing tumor.
Patients can eat and drink normally and take all their usual medications prior to the test. Estrogen containing medications, including the contraceptive pill and hormone replacement therapy, should be stopped for six weeks prior to measuring serum cortisol. This is because estrogen induces cortisol binding globulin and leads to elevations in measured serum cortisol. Any steroid containing medications should also be documented, and avoided if possible, as they may interfere with the hypothalamo-pituitary-adrenal axis, or cross react with the cortisol assay.