Metanephrines for Pheochromocytoma

Neuroendocrine tumors are responsible for approximately 0.3% of cases of hypertension. Prevalence is higher in patients with the following clinical situations:

  • Hyperadrenergic spells
  • Hypertension onset at young age (<20 years)
  • Hypertension resistant to treatment
  • Positive family history
  • Predisposing syndrome such as MEN 2 or neurofibromatosis
  • History of GIST or pulmonary chondromas
  • Incidentally discovered adrenal mass
  • Idiopathic dilated cardiomyopathy
  • Pressor response to anesthesia, surgery or angiography

Measurement of metanephrines is more sensitive than catecholamines because they are more stable and reach higher and sustained levels in the circulation. Measurement of fractionated plasma metanephrines is the best initial test for excluding pheochromocytoma.

A positive test is interpreted as an elevation of metanephrine or normetanephrine. Pheochromocytoma or paraganglioma is likely if the plasma free normetanephrine level is 3-fold higher than the upper limit of the reference range.

Specificity of plasma metaneprhines is 85-89%.The lower specificity means that many patients with hypertension and mildly elevated plasma metanephrines probably do not have pheochromocytoma or paraganglioma.

Blood collection should be performed after an overnight fast and after at least 30 minutes of supine rest, with the patient as comfortable and stress-free as possible. If possible, medications associated with elevated metanephrines should be discontinued at least one week prior to specimen collection.

Keyword: metanephrines pheochromocytoma

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.