This is a clinical research study using I-131 Iodocholesterol which is an experimental radioactive chemical that when injected into the vein, is picked up in the adrenal glands and permits visualization with gamma imaging devices. These images are used in diagnosing a variety of adrenal abnormalities.Prior to the injection of I-131 Iodocholesterol, the patient will receive perchlorate capsules to block any uptake of I-131 by the thyroid gland if this is deemed important. The patient will continue to take these capsules throughout the period of imaging, which may last up to 1 week. The injection of I-131 Iodocholesterol will be given into a vein and the patient will return for images on at least 1 and possibly 2 occasions between 3-7 days after injection. If the case requires it, the patient may also be given a steroid in tablet form, dexamethasone, to take orally prior to and after the injection to suppress normal adrenal function so that the abnormal tissues can be more easily detected.