The patient will be given 5 drops of saturated solution of potassium iodide daily for 2 days prior to the study and will continue for 5 to 7 days later to minimize the radiation dose to the thyroid gland. One to 2 mCi of I 131 1,6-beta-iodomethyl-19-norcholesterol (NP-59) in 10% ethanol, 0.23% polysorbate 80 and 0.9% NaCl will be given intravenously slowly over 1-5 minutes. Anterior and posterior images of the adrenal area will be obtained 72 and 96 hours later. Additional images will be made if indicated. Each image would require 30 minutes carried out in the nuclear medicine laboratory. To verify the exact location of the adrenal glands, renal scan with 99m Tc DTPA or Mag 3 (routine nuclear medicine radiopharmaceuticals) will also be obtained whenever indicated. In some patients, dexamethasone suppression will be carried out to improve the specificity of NP 59 diagnosis for autonomous hormonal secretions by the adrenal tumors.