Dexamethasone suppression tests are used to assess the status of the hypothalamic-pituitary-adrenal (HPA) axis and for the differential diagnosis of adrenal hyperfunction. The low-dose dexamethasone suppression tests are used to assess nonsuppressible cortisol production by adrenal incidentalomas and to differentiate patients with Cushing's syndrome of any cause from patients who do not have Cushing's syndrome. The high-dose dexamethasone suppression tests help to distinguish patients with Cushing's disease (Cushing's syndrome caused by pituitary hypersecretion of corticotropin [ACTH]) from most patients with the ectopic ACTH syndrome (Cushing's syndrome caused by nonpituitary ACTH-secreting tumors).
In cerebral edema , Dexamethasone sodium phosphate injection is generally administered initially in a dosage of 10 mg intravenously followed by 4 mg every six hours intramuscularly until the symptoms of cerebral edema subside. Response is usually noted within 12 to 24 hours and dosage may be reduced after two to four days and gradually discontinued over a period of five to seven days. For palliative management of patients with recurrent or inoperable brain tumors, maintenance therapy with either Dexamethasone sodium phosphate injection or Dexamethasone tablets in a dosage of 2 mg two or three times daily may be effective.