Also Known as partial adrenalectomy. The cortex of adrenal gland produce cortisol, an essential hormone. If a person's adrenal cortex is removed during adrenal surgery, he or she may develop adrenal insufficiency and may need to take steroid medication. To avoid this, surgeons can in some cases preserve some of the normal adrenal cortex. This may be possible if a patient has bilateral adrenal tumors or tumors that are small and clearly not cancer (like aldosterone producing adenomas). This surgery usually involves removal of just the tumor with a thin rim of normal tissue.