Pheochromocytoma

hospitalnursing

A PERCEPTIVE NURSE'S SUGGESTION LED MY HUSBAND AND ME TO A RARE DIAGNOSIS.

My husband, Peter, and I are nurses. About 5 years ago, while we were on vacation, Peter awakened with palpitations, diaphoresis, irregular heartbeat, mild chest tightness, and a dull occipital headache. A vigorous man in his late 30s, he hadn't had health problems other than appendicitis as a teenager. I took him to the emergency department (ED), but by the time we arrived he felt fine. His cardiac workup was normal.

For a few years after that initial episode, Peter developed the same symptoms from time to time but each episode resolved within an hour. Even when he wasn't having symptoms, his diastolic blood pressure (BP) became borderline hypertensive and occasionally reached as high as 120 mm Hg.

One day Peter had an episode while working in the ED. His co-workers attached him to a cardiac monitor and the strip showed paroxysmal atrial fibrillation with a rate of 180 to 200 beats/minute. His BP was 180/110, which the physician attributed to anxiety and baseline hypertension. His bloodwork results showed elevated triglyceride, cholesterol, and fasting glucose levels.

Fearing the worst

Peter's physician prescribed diltiazem, a calcium channel blocker, to combat hypertension; digoxin, to control the atrial fibrillation; and aspirin, to protect him from clot formation. Peter stopped consuming anything that contained caffeine or alcohol. Despite these measures, his unnerving episodes became more frequent, prolonged, and severe, occurring several times a day for weeks at a time. We feared he'd have a myocardial infarction or a stroke, and a feeling of hopelessness crept into our lives.

Then one day at work, Peter became severely short of breath and diaphoretic and was admitted to the intensive care unit (ICU) with hypertension. His electrocardiogram revealed 2:1 atrial flutter and an echocardiogram showed left ventricular hypertrophy.

The nurse who admitted Peter to the ICU, a co-worker of ours for years, told us that the physician had ordered thyroid studies to rule out thyrotoxicosis. Then she asked if he'd ever been screened for a pheochromocytoma. The answer was no, so the physician ordered a 24-hour urine sample for vanillylmandelic acid, metanephrine, and normetanephrine.

This urine test for the breakdown products of catecholamines is the gold standard to confirm or rule out pheochromocytoma. Although generally sensitive, the test sometimes gives false-negative results. If the results are negative and the index of suspicion for this tumor is high, the patient should have a plasma catecholamine test. When Peter's 24-hour urine results showed a serious excess of catecholamines, he was diagnosed with pheochromocytoma.

Rare condition

A rare tumor that typically arises from chromaffin cells in the adrenal medulla, pheochromocytoma produces and secretes the catecholamines norepinephrine, epinephrine, and dopamine. Because chromaffin cells make up the entire sympathetic nervous system, tumors can arise anywhere along the sympathetic chain, and about 10% occur outside the adrenal glands. Those are called extraadrenal pheochromocytomas, or paragangliomas.

Pheochromocytoma causes various signs and symptoms, all arising from the effects of catecholamines in the bloodstream. (See Signs and Symptoms of Catecholamine Excess.) Catecholamines are released in spurts, so episodes like Peter's can last from minutes to hours. In about 0. 1% of patients diagnosed with hypertension, the cause is pheochromocytoma; about 10% of pheochromocytomas are malignant.

Catecholamines influence nearly all tissues and organs in the body to create various metabolic, cardiovascular, electrolyte, and hormonal disturbances. The excesses had raised Peter's lipid and glucose levels. The reason is that catecholamines stimulate the liver to convert glycogen into glucose while causing the pancreas to decrease insulin secretion, so blood glucose levels rise. Catecholamines also mobilize free fatty acids from adipose tissue to increase blood lipid levels.

Hope for a cure

Although a pheochromocytoma had been wreaking havoc in Peter's body, the good news was that it might be curable. Once the diagnosis was made, the next step was to locate the tumor. Because 90% are adrenal, a computed tomography scan of the abdomen typically reveals the tumor, which could be unilateral or bilateral. Peter's adrenals, however, were normal, so we were dealing with a paraganglioma.

Subsequent magnetic resonance imaging of his chest, abdomen, and pelvis showed no tumor, so the physician ordered I-metaiodobenzylguanidine (MIBG) scintigraphy, a nuclear imaging test used to locate extra-adrenal tumors. During MIBG, the patient receives an injected substance that accumulates in catecholamine-producing tumors. He then undergoes testing over 3 days, looking for a "hot spot" on the scan. Sure enough, Peter had a tumor in the periaortic area of his lower abdomen. 0,

Treatment for pheochromocytoma is surgical excision. The best outcomes are achieved in large medical centers where surgeons and anesthesia personnel have experience with the disease. We went to the Mayo Clinic.

Gearing up for surgery

Before Peter underwent surgery, he took a 2-week course of phenoxybenzamine, an alpha-adrenergic blocker. It relieves chronic vasoconstriction due to catecholamine excess and allows increased fluids to expand blood volume before surgery. It also improves the patient's chance of surviving surgery by blunting the wide BP swings caused by manipulating the tumor. Because alpha blockade relieves vasoconstriction, common adverse responses include postural hypotension, syncope, and weakness. For this reason, Peter was started on the beta-blocker propranolol (Inderal) to control tachycardia once he started the alpha-blocker.

Anesthesia for pheochromocytoma surgery is a challenge because the patient's hemodynamic status could become unstable during and after the procedure. Dopamine is used to treat hypotension and nitroprusside is kept on hand to treat hypertensive episodes, which occur most commonly during induction of anesthesia, intubation, or manipulation of the tumor.

Blood pressure swings can occur postoperatively too. Hypotension is more common then hypertension after the tumor is removed because the long-acting alpha blockade is still active. Pressors may be required and ICU monitoring is recommended for the first 24 hours. (For nursing interventions, see Protecting Your Patient after Surgery.)

After Peter's procedure, the surgeon told us that the tumor had been wedged between his aorta and vena cava in the lower abdomen. It slipped out easily and hadn't invaded adjacent tissues.

Unfortunately, the distinction between benign and malignant pheochromocytoma can't be made through tissue analysis. The only reliable indicator of malignancy is tumor invasion into nonchromaffin tissue. Therefore, the patient must have annual urine screening for at least 10 years after surgery. Peter has the test each year on the date of his surgery.

Attentive nurse

Thanks to the attentive ICU nurse who asked Peter about pheochromocytoma testing, he got the correct diagnosis and treatment. If you recognize similar signs in your patient, alert his primary care provider and ask about this simple screening test. As Peter and I learned, it can solve a long-lasting puzzle and mean the difference between life and death to your patient.

SELECTED WEB SITES

EndocrineWeb.com

http://www.endocrineweb.com/tenpercent.html

Oncolink: University of Pennsylvania Cancer Center

http://www.oncolink.upenn.edu

Last accessed on February 5, 2002.

SELECTED REFERENCES

Goldman, L., and Bennett, J. (eds): Cecil Textbook of Medicine, 21 st edition. Philadelphia, Pa., W.B. Saunders Co., 2000.

Ignatavicius, D., et al.: Medical-Surgical Nursing across the Health Care Continuum, 3rd edition. Philadelphia, Pa., W.B. Saunders Co., 1999. Rosen, P.: 5 Minute Emergency Medicine Consult. Philadelphia, Pa., Lippincott Williams & Wilkins, 1999.

Young, W.: "Phaeochromocytoma: How to Catch a Moonbeam in Your Hand," European Journal of Endocrinology. 136(1):28-29, January 1997.

BY KATHARYN F. DAUB, RN, EDD

Katharyn Daub is an assistant professor of baccalaureate nursing at the University of Hawaii in Hilo.

Copyright Springhouse Corporation Mar 2002
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