Endocrinology Book

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PheochromocytomaAka: Paroxysmal Hypertension

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  1. Definition
    1. Catecholamine secreting tumor of the adrenal gland
  2. Epidemiology
    1. Peak ages: 30-60 years
    2. Equal male and female predominance
  3. Presentation: Classic Episodes
    1. Predominant Symptoms
      1. Headache
      2. Diaphoresis or Sweating
      3. Palpitations
    2. Associated Symptoms
      1. Anxiety
      2. Tremor
      3. Pallor
      4. Chest Pain
      5. Epigastric pain
      6. Flushing (rare)
      7. Painless Hematuria (rare)
    3. Timing of episodes
      1. Duration: One hour or less
      2. Frequency: daily to once every few months
  4. Presentation: Other
    1. Resistant Hypertension
    2. Malignant or intra-operative Hypertension
    3. Hypotension episodes (rare)
  5. Diagnostic Clues
    1. Six "H's"
      1. Hypertension
      2. Headache - throbbing (90%)
      3. Hyperhidrosis or excessive sweating (69%)
      4. Heart consciousness or Palpitations (73%)
      5. Hypermetabolism
      6. Hyperglycemia
    2. Rule of 10
      1. Familial (10%)
      2. Malignant (10%)
      3. Multiple or Bilateral (10%)
      4. Extra-adrenal (10%)
      5. Childhood onset (10%)
      6. Recurrence after Surgery (10%)
  6. Differential Diagnosis
    1. Primary Aldosteronism
    2. Carcinoid
    3. Accelerated or Malignant Hypertension
    4. Illicit, OTC or prescribed Sympathomimetic medications
    5. Chemodectoma
    6. Ganglioneuroma
    7. Thyrotoxicosis
    8. Menopause
    9. Panic Disorder
    10. Antihypertensive withdrawal (e.g. Clonidine withdrawal)
  7. Labs: Preparation
    1. Stop any interfering medications
      1. Labetalol (stop for 1 week)
      2. Tricyclic Antidepressant (stop for 2 weeks)
      3. Psychoactive medications (stop for weeks)
      4. Levodopa or Methyldopa
      5. Decongestants
      6. Benzodiazepines
      7. Muscle relaxants (mephenasin, Methocarbamol)
      8. Avoid Tylenol for 48 hours
      9. Avoid Aspirin
    2. Stop other interfering agents
      1. No caffeine, alcohol or Tobacco for 4 hours
      2. Tomatoes
      3. Walnuts
      4. Pineapple
      5. Banana
      6. Eggplant
      7. Avocado
      8. Plums
  8. Labs: Available Tests
    1. Best studies
      1. Plasma Free Metanephrines
        1. Test Sensitivity: 99%
        2. Test Specificity: 89%
      2. Urine Metanephrines (24 hour collections)
        1. Test Sensitivity: 76%
        2. Test Specificity: 94%
    2. Tests with lower efficacy (rarely used now)
      1. Urinary VMA
        1. Normal value under 6.5 mg/day
        2. Imprecise test
        3. Drugs and food interfere with test
        4. Test Sensitivity: 63%
        5. Test Specificity: 94%
      2. Plasma Catecholamines (Norepinephrine, Epinephrine)
        1. Test Sensitivity: 85%
        2. Test Specificity: 80%
  9. Labs: Protocol
    1. First: 24-hour Urine Metanephrine and Urine VMA
    2. Next: Plasma Free Metanephrines
    3. Next: Plasma Catecholamines (equivocal metanephrines)
    4. Final: Clonidine Suppression (positive Catecholamines)
  10. Radiology: Tumor localization
    1. Adrenal CT or Adrenal MRI
      1. Test Sensitivity: 93 to 100%
      2. Test Specificity: 70%
    2. MIGB Scan (metaiodobenzyl-guanidine)
      1. Test Sensitivity: 77 to 90%
      2. Test Specificity: 95 to 100%
      3. Good for looking for tumors in unusual places
  11. Management
    1. Preoperative Medical Management
      1. Alpha Adrenergic Receptor antagonist (2 weeks pre-op)
        1. Phenoxybenzamine PO bid
        2. Phentolamine IV prn
      2. Beta Blocker (only start after alpha blockade)
        1. Propranolol PO qid
    2. Surgical Management
      1. Laparoscopic adrenalectomy Indications
        1. Single, small adrenal tumors
        2. Hypertension controlled
      2. Open Adrenalectomy
        1. Adrenal tumor size over 7 cm
    3. Intra-Operative Management
      1. Continuous Arterial-line Blood Pressure Monitoring
      2. Treat Hypotension
        1. Fluid management
        2. Consider pressor support
      3. Treat Hypertension
        1. Phentolamine
        2. Nitroprusside
      4. Treat tachycardia or ectopy
        1. Beta Blocker
    4. Adjunctive treatment for malignant Pheochromocytoma
      1. Chemotherapy
        1. Cyclophosphamide
        2. Dacarbazine
        3. Vincristine
      2. MIGB (metaiodobenzyl-guanidine I-131)
      3. Metyrosine 1 gram every 6 hours
        1. Depletes tumor Catecholamine stores
  12. Course
    1. Persistent Hypertension in 25% of treated patients
  13. Monitoring
    1. Screen Urine Metanephrines annually
    2. Screen Urine Catecholamines annually
  14. References
    1. Bailey (2001) CMEA Medicine Lecture, San Diego
    2. (Feb 2001) Ann Intern Med

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