About the Endocrine Surgery Center
Personalizing Medicine through:
► Quality patient care
► Specialized surgical expertise
► Advanced medical education
► Innovative clinical research
The Endocrine Surgery Center at the University of Arizona consists of a multidisciplinary team of specialists dedicated to providing quality, innovative and comprehensive treatment of benign and malignant diseases of the endocrine system (thyroid gland, parathyroid glands, adrenal glands and pancreas).
Our specialists are experts in their fields and provide the experience, knowledge, skills and enthusiasm that patients deserve. We combine the diagnostic and treatment strengths of leading medical experts, including, endocrine surgeons, transplant surgeons, endocrinologists, geneticists, radiologists, radiation oncologists, pathologists and oncologists, to unify state-of-the-art treatment options into personalized care. Partnering with the referring physician, we can provide the highest quality and greatest continuity of care for our patients.
The Endocrine Surgery Center is the only center in the Southwest that is solely dedicated to the diagnosis and treatment of endocrine diseases, including complex, advanced and recurrent diseases. The Endocrine Surgery Center collaborates closely with the University Medical Center and the Arizona Cancer Center, one of only 39 comprehensive cancer centers designated by the National Cancer Institute.
Contact Information & Location
Arizona Cancer Center UMC North
3838 North Campbell Ave
Tucson, AZ 85719
Tel: (520) 694-CURE (2873)
Cushing’s syndrome is a disease that results from excessive cortisol (steroid) secretion, also called hypercortisolism, from the adrenal glands (a pair of glands just above the kidneys). The clinical symptoms and signs of hypercortisolism are common in the general population, so Cushing’s syndrome may be underdiagnosed. Studies have shown that about 1% of patients with newly diagnosed diabetes and 3% of patients with poorly controlled diabetes have surgically proven Cushing syndrome.
Cushing’s syndrome is categorized as follows:
Corticotropin (also called adrenocorticotropic hormone [ACTH]) dependent (80% of patients)
Excessive secretion of ACTH results in overproduction of steroids and in hyperplasia (an abnormal increase in the number of normal cells) of both adrenal glands. The most common cause is a pituitary gland adenoma (a benign tumor), with a female:male ratio of 8:1.
A far less common cause of corticotropin-dependent Cushing syndrome is ectopic (away from the normal position) ACTH secretion, with a female:male ratio of 1:2. Ectopic ACTH secretion is typically due to small-cell carcinoma of the lung, malignant tumors of the thymus, and pancreatic cancer, but it can also develop from carcinoid tumors, medullary thyroid cancer, and pheochromocytomas.
Corticotropin (ACTH) independent (20% of patients)
This form of Cushing’s syndrome results from cortisol hypersecretion by an autonomously functioning adrenal gland. Half of the cases are due to an adrenal adenoma (a benign tumor), and the other half are due to an adrenocortical carcinoma (a malignant tumor). The female:male ratio for adrenal adenomas is 3:1; for adrenocortical carcinomas, 2:1.
Clinical Symptoms and Signs
Cushing’s syndrome involves a wide range of symptoms and signs that are commonly found in the general population, often resulting in a delayed diagnosis or in misdiagnosis.
No signs absolutely define Cushing’s syndrome, but the following symptoms often occur:
- Facial plethora (red discoloration) (70% of Cushing’s syndrome patients)
- Purple striae (stretch marks) (60%)
- Muscle weakness (60%), associated with muscle hypotrophy (degeneration) and thinning of the limbs
- Easy and frequent bruising (40%), with the skin becoming thin and fragile
Other symptoms are more common in the general population and therefore make Cushing's syndrome harder to diagnose:
- Weight gain or obesity (90% of Cushing's syndrome patients), usually central obesity, with rounding of the face and with posterior neck fat deposition
- Hypertension (high blood pressure) (80%)
- Hirsutism (abnormal hairiness) or, in females, balding (70%)
- Menstrual irregularity (70%)
- Depression, irritability, impaired memory, decreased concentration, or fatigue (60%)
- Sexual dysfunction (60%)
- Acne (30%)
- Headache (10%)
Testing for Cushing’s syndrome is recommended for patients with an adrenal incidentaloma (an asymptomatic tumor found incidentally) or an adrenal mass; patients with multiple or worsening clinical symptoms (see above); or patients who had hypertension or osteoporosis at an early age. Children should be tested if their weight is abnormally increasing or their height decreasing.
The most common cause of Cushing’s syndrome is iatrogenic (a complication of medical treatment), so before performing a comprehensive workup, the patient’s medications must be carefully evaluated. Initial tests include a 24-hour urinary free cortisol (UFC) measurement (positive, 4 times the upper limits of normal); a low-dose overnight dexamethasone suppression test (with 1 mg given at 11 pm and plasma cortisol level measured at 8 am; normal, <1.8 µg/dL); and a plasma ACTH level measurement (< 5 pg/mL = ACTH independent, > 20 pg/mL = ACTH dependent).
Patients who are pregnant or who have epilepsy should undergo UFC measurement; patients in renal failure should undergo the overnight dexamethasone suppression test.
Patients with negative tests do not have Cushing’s syndrome and no further testing is necessary.
Patients who have biochemical evidence of Cushing’s syndrome and ACTH suppression have Cushing’s syndrome of adrenal origin; they require adrenal imaging.
Patients with an elevated ACTH level have either ectopic Cushing’s syndrome or pituitary-dependent Cushing’s disease. Further biochemical testing and imaging should help differentiate between those 2 diagnoses.
When test results are negative but either clinical suspicion remains high or clinical symptoms worsen, the tests should be repeated in 6 months.
When test results are equivocal but clinical suspicion remains high, the tests should be repeated, and the patient should be referred to an endocrine specialist for further testing.
The following factors can produce false-positive results:
- Chronic alcohol use
- Certain medications
- Serious illness or physical stress
- Major depression
- Morbid obesity (in which case urine free cortisol levels are usually normal)
To localize the sites of Cushing’s syndrome, computed tomography (CT) is the best imaging modality, because it provides good anatomic detail and useful information on tumor density (which is measured in Hounsfield units). Magnetic resonance imaging (MRI) may also be used, especially in patients allergic to the iodine-based dye.
Most adrenal tumors are unilateral (involving just 1 adrenal gland), though rare, bilateral (both sides) adrenal disease does occur. Most patients are candidates to undergo laparoscopic (minimally invasive) surgery. A unilateral laparoscopic adrenalectomy (removal of the adrenal gland) is performed when Cushing’s syndrome is caused by a single adenoma. However, if the adrenal mass is > 6 cm or has features suggestive of cancer, an open (involving a traditional incision) adrenalectomy is performed.
Patients with bilateral adrenal disease or those with pituitary-dependent Cushing’s disease that have failed appropriate treatment require a bilateral adrenalectomy.
Successful surgery will result in transient hypocortisolism (low cortisol secretion). Patients will require steroid replacement after surgery until the remaining adrenal gland has optimal function, often for more than 6 months (median, 30 months). The steroid medication is slowly tapered over time. Patients who undergo a bilateral adrenalectomy will require lifelong steroid replacement.
Patients with benign tumors are cured after surgery. However, patients with adrenal cancer are at risk of recurrence and metastasis (spread throughout the body). It is often difficult to differentiate between benign and malignant tumors, so careful biochemical monitoring is required.
Most patients experience symptomatic improvement, but up to a third have persistent symptoms. The physical symptoms of Cushing’s syndrome resolve in more than 75% of patients, but it takes many months (mean, 7 to 9 months). Diabetes is cured in 79% of patients; hypertension is cured or improved in nearly 70%. Yet even patients whose symptoms do not completely resolve often report overall improvement in their quality of life.