pheochromocytoma
PHEOCHROMOCYTOMA
Pheochromocytoma is a rare adrenal gland tumor that may precipitate life-threatening hypertension.
It can occur at any age but usually occurs during young to mid-adult life.
Majority of patients presents with ≥1 of the following hypertension resistant to standard antihypertensive treatment, hypertensive crisis with malignant hypertension, hypertensive encephalopathy, aortic dissection, or myocardial infarction and paroxysmal symptoms which suggest seizure disorder, anxiety attacks or hyperventilation.

Pheochromocytoma Treatment

Pharmacotherapy

Alpha-Adrenergic Blockade

  • First-line therapy used to minimize complications prior to surgery

Phenoxybenzamine

  • Action: Powerful irreversible alpha-adrenergic blocker of the alpha receptors in the smooth muscles
  • Effects: Oral administration results in an onset of action w/in a few hr & persists for up to 3-4 days
    • Used to control the hypertension caused by excessive catecholamine release by pheochromocytoma

Selective Alpha1-Antagonists

  • Eg Doxazosin
  • Action: Selective blockade of alpha1-adrenoreceptors
  • Effects: Limited use in pheochromocytoma, Phenoxybenzamine is more effective
  • May be used to treat individual paroxysms
  • May also may be used to treat hypertension while pheochromocytoma workup is ongoing
    • Better tolerated than Phenoxybenzamine
    • Prevent serious pressor crisis if pheochromocytoma is present

Beta-Blockers

  • Eg Propranolol, Atenolol
  • Administer only after alpha blockade has been induced
    • W/o alpha blockade paradox increase in BP may occur
  • Action: Competitive antagonists of catecholamines at beta-adrenergic receptors
  • Effects: Used to treat tachycardia that may develop w/ alpha blockade
    • Assist in preventing catecholamine-induced arrhythmias
  • Low doses are usually sufficient

Calcium Channel Blockers

  • Eg Nifedipine, Amlodipine
  • Used as add-on treatment to alpha-adrenergic receptor blockers to further improve cardiovascular function peri-operatively
  • Action: Blocks slow calcium channels to prevent calcium ion flow into the cell
  • Effects: Vasodilatation, reduced afterload, peripheral resistance & blood pressure

Metirosine (Metyrosine)

  • Action: Inhibits tyrosine hydroxylase which inhibits synthesis of catecholamines by the tumor
  • Effects: Simplifies chronic management
  • Should be used if other agents are ineffective or when tumor destruction will be marked
Digital Edition
Asia's trusted medical magazine for healthcare professionals. Get your MIMS Endocrinology - Malaysia digital copy today!
Sign In To Download
Editor's Recommendations
Most Read Articles
Pearl Toh, 22 Oct 2020
The combination therapy comprising carfilzomib, cyclophosphamide and dexamethasone (KCd) is effective, with a tolerable safety profile, in an Asian cohort with high-risk multiple myeloma (MM) — thus providing a more economical alternative as a potential upfront regimen in resource-limited settings, according to leading experts during a myeloma education webinar.
Roshini Claire Anthony, 13 Nov 2020

Diabetes is a key risk factor for heart failure (HF), which is the leading cause of hospitalization in patients with or without diabetes. SGLT-2* inhibitors (SGLT-2is) have been shown to reduce the risk of hospitalization for HF (HHF) regardless of the presence or absence of diabetes.

Pearl Toh, 5 days ago
Inhaled corticosteroid (ICS) should be the mainstay of long-term asthma management — such is the key message of the latest Singapore ACE* Clinical Guidance (ACG) for asthma, released in October 2020.
Elvira Manzano, 17 Nov 2020
Invasive fungal infections, particularly those caused by Candida species, are common in hospitalized, immunocompromised, or critically ill patients and are associated with considerable morbidity and mortality.