Aldosterone Producing Adenoma (APA) (Conn’s Syndrome)

From a surgical stand point APA is the most important cause of hyperaldosteronism and is commonly called Conn’s snydrome . It accounts for about 30% of hyperaldosteronism. Typically with Conn’s syndrome the degree of hyperaldosteronism is greater than in IHA. Conn’s sydrome is caused by a discrete benign tumor of the adrenal gland (APA). Why an adenoma develops isn’t clearly understood. As with other causes of hyperaldosteronism, it is suspected when a patient has significant high blood pressure and low potassium levels. Further screening with blood test that show an elevated aldosterone level and suppressed renin activity suggests the diagnosis. It is confirmed with a 24 hour collection of urine to measure the amount of aldosterone secreted. These tests can be influenced by a variety of medications and dietary issues and requires an experienced endocrinologist for the best accuracy.

Once the diagnosis is made, then efforts to discern the cause of the over secretion are undertaken. A CT scan or MRI is performed. If the patient is under 40 years old and a clear tumor is seen in one gland with a clearly normal gland on the other side then, generally, it is appropriate to consider surgical removal of the adrenal gland with the adenoma. Most of these tumors are small (2 cm) and laparoscopic removal is the standard of care. We will discuss the surgical techniques later.

Overall the accuracy of these imaging studies is very good (about 80%). However, as patients age, small benign non-functioning tumors can appear in the adrenal gland. Over the age of 40 2-3% of the population may have these incidentally noted tumors. These are called incidentalomas and we will consider them on a subsequent page. Because of this, in patients over 40 years of age, it can not be assumed that a tumor found on imaging is the cause of the hyperaldosteronism. As an example , a patient could have an incidentaloma seen on CTscan in one gland, but the source of the hyperaldosteronism could be a tiny adenoma or primary adrenal hyperplasia (PAH) in the other gland. Therefore in patients over 40 we often recommend adrenal vein sampling (AVS). This is an invasive technique where a catheter is inserted into a large vein in the groin and samples of blood are taken from the vein of each adrenal gland and aldosterone levels are measured. If the aldosterone secretion is significantly elevated from one gland then this is the source of the problem regardless of what the imaging studies show. Some physicians think AVS should always be done in cases of primary hyperaldosteronism. It is a matter of on going debate. AVS is not without risk. It requires significant experience by the radiologist for the best accuracy and it is not available in all communities. There is significant expense involved. There is a small risk of bleeding or damage to the adrenal gland.

Once the diagnosis is made and the source of the problem is clearly located to one gland. Then laparoscopic adrenalectomy is performed.  In appropriately selected patients, surgery controls high blood pressure in more than 70% of patients at one year after surgery. Over the next 5 years some patients may have their high blood pressure return, however, it is usually easy to control. Issues with low potassium are generally corrected with resection of the adenoma. We will review the risks and benefits of surgery on a separate page.