Can a adrenal adenoma stop functioning?

No. An adrenal adenoma is a benign tumor of the adrenal gland. It typically causes no complications. Someimes these tumors become "active" or "functioning" producing hormones, often in excess of what the adrenal glands typically produce. This excess of hormones can cause primary aldosteronism, Cushing's syndrome and other medical conditions. They do not stop hormone production.once functional.
Yes and no. Most adrenal adenomas are nonfunctioning. However if an adenoma is functioning, i.e. Secreting excess of hormone, it will not usually stop functioning. Functioning tumors are usually removed surgically to prevent adverse affects of excess hormones, like cushing's disease and hyperaldosteronism.