The cortex is the part of the adrenal gland that makes cortisol Cortisol - a glucocorticoid that controls glucose production and suppresses the immune system , a hormone that is crucial for life. If the patient does not have enough adrenal cortex left, he or she may develop adrenal insufficiency and may need to take steroid medication. ( See What are the potential complications? ) In cases of bilateral adrenal tumors (. a tumor in both adrenal glands) or tumors that are small and clearly not cancer (like aldosterone Aldosterone - a mineralocorticoid that controls blood pressure producing adenomas), some surgeons may perform a cortical-sparing adrenalectomy Cortical-sparing adrenalectomy - an operation to remove the part of an adrenal gland that has the tumor. Also called a partial adrenalectomy. to keep as much of this normal cortex as possible. This usually involves looking at the entire adrenal gland and cutting out just the tumor with a thin rim of normal tissue.