Pheochromocytoma: Dx markers

Introduction to Pheochromocytoma

25-50% of Pheo patients who die in hospital do so during anesthesia induction or surgery. Can be part of multiple endocrine adenoma IIa or IIb, autosomal dominant. MEN IIa is medullary thyroid, parathyroid adenoma, and pheo. MEN IIb aka pheo in assoc w/ phakomatoses (von Recklinghausen neurofibromatosis, VHL, cerebellar hemangioblastoma). MRI or CT to locate tumors. Familial often bilateral.

Signs/Symptoms/Diagnosis

sweating, HA, HTN, orthostatic hypotension, Hx HTN or arrhythmia w/ anesthesia or abdomainal exam. Paroxysmal HA + sweating + HTN more sensitive than any single blood test. Other Dx tests include : Vanillylmandelic acid, Catecholamine (nl 200-2000, pheo 2000-20,000), Metanephrine

Treatments

Using alpha-blocker (prazosin, phenoxybenzamine) prior to surgery reduces mortality from 50% to 5%. Alpha-blocker Rx also reduces fasting glucose level and decreases myocarditis. If arrhythmia or tachycardia use propranolol with alpha blocker. Don’t use beta-blocker alone, can have unopposed alpha severe hypertension. If bp is < 165/90 for 48hrs, orthostatic hypotension IS present, no ST-T changes, and no PVC’s pt can most safely undergo anesthesia and surgery. Avoid desflurane because of non-neurogenic chatecholamine release. Use nitroprusside for HTN, surgerical manipulation of tumor can cause blood chatechol levels of 200,000-1,000,000. My need exogenous chatecholamines after venous drainage ligated.

Pheochromocytoma Markers

• Vanillylmandelic acid excretion (Sensitivity/Specificity/PPV/NPV) 81/ 97/ 27.0/ 0.20
• Catecholamine excretion (Sensitivity/Specificity/PPV/NPV) 82/ 95/ 16.4/ 0.19
• Metanephrine excretion (Sensitivity/Specificity/PPV/NPV) 83/ 95/ 16.6/ 0.18
• Abdominal computed tomography (Sensitivity/Specificity/PPV/NPV)92/ 80/ 4.6/ 0.10
• Concurrent paroxysmal HTN, H/A, sweating, and tachycardia[‡] (Sensitivity/Specificity/PPV/NPV) 90/95/18.0/0.10

‡Data for concurrent paroxysmal symptoms are best estimates from available data.

Modified from Pauker SG, Kopelman RI (see citation in Sources below).