Anatomy and Function
The adrenals are relatively small and paired glands located above the kidneys. The inner core of the adrenal gland is called the medulla, which produces catecholamines, commonly known as adrenaline. The largest part of the adrenal gland is the outer three layers, collectively termed the cortex, and each produce their own specific steroid hormones (aldosterone, cortisol, and sex hormones). Taken together, these hormones are responsible for a myriad of crucial functions such as blood pressure control, regulation of metabolism and stress response, fluid and electrolyte balance, influence blood sugar levels, immune function, and sex characteristics, amongst others.
There are three categories of adrenal disease that require surgical intervention. An adrenal tumor is removed when it:
- Produces too many hormones (functional tumor)
- Has physical characteristics of potential malignancy and no hormonal activity (nonfunctional tumor)
- Adrenal malignancy (cancerous tumor)
Functional tumor types
Benign (nonmalignant) tumors that produce too much aldosterone are termed aldosteronomas and cause elevated blood pressure, low potassium levels, and often excessive urination and thirst.
Benign tumors that produce too much cortisol cause a condition known as Cushing’s syndrome and can cause high blood pressure, altered metabolism and elevated blood sugars, weight gain, skin changes, weakness, depression, and have an adverse effect on immune function.
Tumors that secrete too much adrenaline are termed pheochromocytomas. The majority of these are benign but 10% can be malignant and 10% can occur on both sides.
Virilizing or feminizing tumors from excessive sex hormone production are rare, but most are malignant.
Tumors that are found incidentally on radiology imaging for other reasons are termed "incidentalomas". These occur in about 4% of the population, increasing with age. Once found, they are usually tested for excessive hormone production. If they are nonfunctional and a size of less than 4cm (determine via CT or MRI imaging), they are considered benign and are observed rather than removed. Observation typically entails the need for repeat imaging and labs every 6 – 12 months (25% will grow and 20% will hypersecrete over a 10-year period).
Tumors that are greater than 4cm have an increased risk of malignancy with increasing size and are usually removed surgically.
There are two general categories of malignant adrenal tumors: Cancer arising in the adrenal gland or a different cancer that spreads to the adrenal gland.
Cancer that arises within the adrenal gland itself is termed an adrenocortical carcinoma. Fortunately, these tumors are rare and account for only 1% of all adrenal tumors with an incidence of 1 case per million. About 3 out of 4 secrete excessive hormones.
Cancer that spreads from another organ is considered a “metastasis” to the adrenal gland, and most often originates from a lung or kidney cancer.
There are many tests used to diagnose an adrenal tumor. Tests are administered based on the type of tumor suspected, symptoms, age and overall health.
Blood and urine tests. To determine the functionality of an adrenal tumor, both blood and urine tests are ordered to measure the various hormone levels at that particular time. Provocative blood tests may also be necessary to help establish a diagnosis. In these tests, a synthetic but natural hormone, steroid, or salt solution is administered and the subsequent blood levels of the released or suppressed adrenal hormone response to those agents are measured. This helps determine if the adrenal tumor is directly responsible for the condition.
CT and MRI. Imaging is an essential component of adrenal gland evaluation. CT scans and MRI are standard and inform which gland or glands harbor the tumor, the size and extent of the tumor, and tumor’s various technical structure measurements which provide further evidence in favor of or against malignancy.
MIBG scan. An MIBG nuclear scan is sometimes necessary to aid in the diagnosis of a pheochromocytoma and the location of the disease.
Adrenal vein sampling. In this procedure, an interventional radiologist inserts a vascular catheter through a leg vein and advances it to the main left and right adrenal veins that drain the adrenal blood into general circulation. The concentration of the hormone being measured should be significantly higher on the suspected tumor side. This test can help further clarify and confirm the diseased gland and therefore aid in surgery plans.
Surgery is the only cure for adrenal tumors. Surgery is indicated for:
- All functional tumors localized to a single adrenal gland regardless of size
- Nonfunctional incidental tumors greater than 4cm (some exceptions depending on other clinical criteria)
- Most tumors suspicious for malignancy
The surgical removal of an adrenal gland is called adrenalectomy. Minimally invasive surgery performed either laparoscopically or robotically is the preferred technique. We have been performing minimally invasive adrenalectomy since the mid 1990s, when it was first confirmed a safe and effective procedure for adrenalectomy. The minimally invasive approach allows for small incisions and scars, less postoperative pain, shorter hospitalization, and faster recovery. Infrequently, a larger incision/open procedure is necessary to remove an exceptionally large tumor or one that is malignant.
The laparoscopic or robotic adrenalectomy is performed under general anesthesia. Four to five small incisions (5 - 10mm) are made, mostly below the ribs on the side of the adrenal gland being removed. The surgery takes approximately 1 ⅕ to 2 hours and most patients stay overnight. Although there is no sensation from the site that the adrenal was removed, patients commonly experience shoulder pain, which originates from the diaphragm due to it’s proximity to the targeted adrenal gland and possibly from the gas used to fill the abdomen for the procedure. Mild to moderate incision pain can also be expected.
Following surgery, your vital signs and other pertinent clinical information will be monitored and a blood test may be ordered. Occasionally supplemental hormones are necessary after removing an adrenal gland, but in the majority of cases, residual hormone levels produced by the remaining gland will provide adequate hormones levels.
Following discharge, heavy lifting, athletic endeavors, or other physically arduous activities should be avoided for about 4 weeks until the incisions site is healed, and hormone levels recover. There are no dietary restrictions. Post-operative appointments with the surgeon and endocrinologist will be made to monitor results and care.