The adrenal glands are small, triangular-shaped organs situated directly on top of each kidney. They are a crucial component of the endocrine system, producing hormones that regulate metabolism, blood pressure, and the body’s response to stress. An adrenal adenoma is a common, usually benign (non-cancerous) tumor that develops within these glands.
This growth is the most frequent tumor found in the adrenal glands, originating in the outer layer, known as the adrenal cortex. Although many of these tumors remain harmless, their discovery often initiates a detailed evaluation.
Characteristics and Classification
Adrenal adenomas are typically small, slow-growing masses classified based on their hormonal activity. The majority are considered non-functional, meaning they do not produce excess hormones. These non-functional growths are often discovered incidentally during imaging scans performed for unrelated medical concerns.
The second, smaller group is known as functional or active adenomas because they actively synthesize and secrete excess adrenal hormones. This overproduction, such as of cortisol or aldosterone, leads to recognizable symptoms and requires clinical attention. The primary concern is not malignancy, which is rare, but whether the tumor is causing an imbalance in the body’s hormone levels.
Clinical Presentation and Symptoms
Non-functional adenomas rarely cause symptoms, but functional adenomas can lead to significant health issues due to hormone overproduction. When the tumor secretes excess aldosterone, the condition is known as primary aldosteronism (Conn Syndrome). This often presents as hypertension (high blood pressure) that is resistant to standard medication regimens.
Excessive aldosterone causes the kidneys to excrete too much potassium, leading to low potassium levels (hypokalemia), which can cause muscle weakness and fatigue. Conversely, if the adenoma overproduces the stress hormone cortisol, it results in symptoms associated with Cushing Syndrome. These effects include weight gain concentrated in the trunk and face, easy bruising, and muscle weakness. High levels of cortisol can also impair glucose metabolism, leading to elevated blood sugar and potential diabetes.
Detection and Evaluation Process
Adrenal adenomas are frequently described as “incidentalomas” because they are often found by chance during abdominal computed tomography (CT) or magnetic resonance imaging (MRI) scans. Once identified, the evaluation focuses on two main goals: determining hormonal activity and assessing the tumor’s physical characteristics. Hormonal testing involves blood and urine analysis to measure levels of cortisol, aldosterone, and catecholamines to determine functionality.
Imaging characteristics help differentiate a benign adenoma from a potentially malignant tumor, such as adrenocortical carcinoma. Benign adenomas typically appear homogeneous, well-circumscribed, and usually measure less than four centimeters in size. On non-contrast CT scans, specific measurements like a low density (less than 10 Hounsfield Units) or a high “washout” rate of contrast dye strongly indicate the mass is benign.
Management and Treatment Options
The management plan for an adrenal adenoma is determined by its size, imaging features, and functionality. Small, non-functional adenomas displaying benign imaging characteristics are typically managed with active surveillance. This involves periodic follow-up scans and blood tests to monitor for growth or the development of hormonal activity.
Intervention is generally recommended in two main scenarios. Functional tumors are usually treated either with medication to block the effects of excess hormones or through surgical removal (adrenalectomy). Adrenalectomy may also be recommended for non-functional adenomas that are large (exceeding four centimeters) or those with suspicious imaging features, to definitively rule out malignancy.