Iodocholesterol I-131 is a radioiodine-labeled cholesterol analog used as a diagnostic agent for Cushing's syndrome, hyperaldosteronism, and pheochromocytoma. Iodocholesterol I-131 accumulates in tissues where steroid hormones are produced, including the adrenal glands the ovaries and the testes. After binding to low-density lipoprotein (LDL) receptors on adrenocortical cells, Iodocholesterol I-131 is internalized. As cholesterol is the precursor for all adrenocortical steroid hormones, areas of hormonal hypersecretion can be visualized using scintigraphy and the adrenocortical function can be assessed.