Tyramine reaction

Background

• Occurs when patient taking a monoamine oxidase inhibitor (MAO-I) ingests tyramine
  • Tyramine is a dietary amine similar to amphetamine normally metabolized by MAO
  • Tyramine is a monoamine and acts indirectly to release catecholamines.
  • Tyramine is typically metabolized by monoamine oxidase in the gut, a process that MAOIs interfere with.
  • Tyramine is found in preserved meat, fish, cheese, alcohol, and protein-rich foods which are particularly likely to contain bacteria that convert amino acids into monoamines like tyramine.

Clinical Features

• Rapid onset (within 15-90 minutes of ingestion) of:
  • Severe occipital or temporal headache
  • Sympathomimetic effects: hypertension, diaphoresis, mydriasis, palpitations, chest pain
• Syndrome usually resolves on own over 6 hours

Differential Diagnosis

Hypertension

• Hypertensive emergency
• Stroke
• Sympathetic crashing acute pulmonary edema
• Ischemic stroke
• Intracranial hemorrhage
• Preeclampsia/Eclampsia
• Autonomic dysreflexia
• Scleroderma renal crisis
• Acute glomerulonephritis
• Type- I myocardial infarction
• Volume overload
• Urinary obstruction
• Drug use or overdose (e.g stimulants, especially alcohol, cocaine, or Synthroid)
• Renal Artery Stenosis
• Nephritic and nephrotic syndrome
• Polycystic kidney disease
• Tyramine reaction
• Cushing's syndrome
• Obstructive sleep apnea
• Pheochromocytoma
• Hyperaldosteronism
• Hyperthyroidism
• Anxiety
• Pain
• Oral contraceptive use

Evaluation

• ECG: monitor for cardiac ischemia
• CT head: if patient has focal neurologic findings or persistent, severe headache

Management

• Hypertensive emergency: phentolamine is agent of choice
  • 2.5-5mg IV q5-15min until blood pressure controlled
  • Duration of action <1 hour
• Beta-blockers contraindicated

Disposition

• Discharge home if asymptomatic after 4 hours of observation