Adrenal adenomas are benign tumors in the adrenal glands. The adrenal glands lie on top of the kidneys and synthesize and release hormones. Depending on the location of the tumor, it may increase the secretion of cortisol, aldosterone, adrenalin or steroid hormones. Most adrenal adenomas are asymptomatic and only identified after a CT scan or MRI conducted for unrelated reasons. Adrenal adenomas that secrete hormones are called functioning tumors. A review article in the "European Journal of Endocrinology" reported the prevalence of adrenal adenomas in the general population is approximately 2 percent. This article also notes that the chance of a benign adrenal tumor becoming malignant is 1 in 1000.
Subclinical Cushing's Syndrome
Adrenal tumors that increase the secretion of cortisol are the most common adrenal functioning tumors. A study in the journal "Hormones" reported that on average 9 percent of adrenal adenomas cause Subclinical Cushing's Syndrome (SCS). Cushing's Syndrome is an endocrine disorder caused by high levels of cortisol in the blood. The symptoms that have been reported in patients with SCS are hypertension, hyperglycemia and obesity. Rarely, symptoms progress to overt Cushing's Syndrome.
Aldosteronomas
Adrenal adenomas that originate in cells of the zona glomerulosa in the adrenal cortex may cause an increase in the synthesis and release of aldosterone. The review in the journal "Hormones" noted that between 1.6 and 3.3 percent of adrenal adenomas are characterized as aldosteronomas. Aldosterone regulates sodium reabsorption and phosphate secretion in the kidneys. An oversecretion of this hormone, sometimes referred to as Conn's Syndrome, can cause uncontrollable hypertension, muscle weakness, cramping and fatigue.
Pheochromacytoma
If the tumor is localized in chromaffin cells of the adrenal medulla, it may increase the release of adrenalin. This type of tumor is called pheochromacytoma and the study in the journal "Hormones" reported that on average 3 percent of adrenal adenomas are pheochromacytomas. The increase in adrenalin can cause symptoms of increased heart rate and blood pressure, anxiety, headaches and weight loss.
Steroid Hormone Producing Tumors
Rarely, adrenal adenomas over-secrete androgens or estrogens. Tumors that elevate adrogen levels may cause increased growth of facial hair, a deepening of the voice and in women can cause menstrual dysfunction. Tumors that increase female sex steroids in men can cause impotence and increased breast growth.
Treatment
In cases of nonfunctioning adrenal adenomas that are larger than 5 centimeters, aldosteronomas and pheochromacytomas, the most common treatment is laparoscopic adrenalectomy. A review article in the "Annals of Internal Medicine" noted that this is a minimally invasive surgical procedure. The authors of this study suggested that patients with non-secretory adrenal tumors smaller than 5 centimeters be monitored with follow-up CT scans. The review in the journal "Hormones" mentioned that there has been controversy over the preferred treatment of patients with Subclinical Cushing's Syndrome. The authors of this study recommend that a non-surgical approach be taken for patients that do not exhibit symptoms and in those older than 75.
