Pheochromocytoma: Current Concepts of Diagnosis and Treatment

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Abstract
Accurate diagnosis is of paramount importance and depends largely on the physician considering this disease in his differential diagnosis. Although pharmacological tests have been used as aids in diagnosing this disease, they are of limited usefulness and an accurate diagnosis can only be established on the basis of demonstrated increased urinary excretion of the catecholamines and/or their metabolites. Great care must be taken so that only specific chemical methods are used in these determinations since many "screening" tests, especially for vanillylmandelic acid (VMA), are non-specific and give false positive results due to dietary factors. Localization of the tumor site after the diagnosis is firmly established is important only to rule out the presence of the very rare extra-abdominal tumors. Preparation for surgery with either adrenergic -blocking drugs or inhibitors of catecholamine synthesis is vital. Dibenzyline has proved useful in preoperative management and is given for 1 to 2 wk. prior to surgery to achieve normal blood pressure and eliminate attacks. [alpha]-Methyl-para-tyrosine ([alpha]MPT), an inhibitor of catecholamine synthesis, is also useful. These medications can also be used successfully for medical management of the patient with metastatic or otherwise inoperable pheochromocytoma. Adequate anesthetic managment of the patient with pheochromocytoma requires constant monitoring of changes in vital signs. This can be achieved adequately only by continuous recording of the electrocardiogram, intra-arterial blood pressure, and the venous pressure. Halothane was used as the principal anesthetic medication in a recent series of 8 patients undergoing surgery because 1 can partially regulate the blood pressure by altering its concentration in the inspired air, but its use is to be recommended only when [beta]-andrenergic-blocking drugs, such as propranolol, are available to counteract cardiac arrythmias. Following tumor removal the characteristic precipitous fall in blood pressure to hypertensive levels is best treated with transfusions of blood and plasma and/or 5% human albumin in saline rather than with pressor drugs.