Test Directory

• Normetanephrine, Plasma
• Metanephrine, Plasma

Evaluation of catecholamine-secreting tumors of the adrenal medulla (pheochromocytomas) and extra-adrenal sympathetic and para-sympathetic paragangliomas.

Specimen Type: Plasma

Collection Container: Lavender Top (EDTA)  

Desired Specimen Volume: 1.2 mL 

1. The patient should be in a fully recumbent position (lying down) for at least 20 minutes before and during sample collection.
2. Collect chilled lavender top (EDTA) tube via venipuncture. 
3. Invert to mix with preservatives.

1. Separate plasma from cells ASAP or within 24 hours of collection.
2. Transfer 1.2 mL of plasma to LabCorp PP transpak frozen purple tube and freeze immediately.

Patient should be fasting overnight (water and non-caffeinated soft drinks are permissible). Patient should avoid alcohol, coffee, tea, tobacco and strenuous exercise prior to collection. See Limitations section for more information about other potential causes of elevated metanephrines.

Transport to the laboratory frozen. 

See patient report.

The low prevalence of PPGL combined with the limited diagnostic specificity of the metanephrine test means that false-positive results far outnumber true-positive results. As outlined in the Endocrine Society Guidelines, all patients with positive test results should receive appropriate follow-up according to the extent of increased values and clinical presentation of the patient. The nature of this follow-up is a matter of clinical judgment based on the pretest probability of tumor and the extent and pattern of increases in test results.

Inappropriate sampling conditions, as well as a number of medications and foods, should be considered as potential causes of borderline elevations of plasma metanephrine and/or normetanephrine. These include:

• selective serotonin and norepinephrine reuptake inhibitors (SSNRIs)
• tricyclic antidepressants
• alpha blockers
• monoamine oxidase inhibitors
• caffeine
• cigarette smoking
• strenuous exercise

Confirmatory testing after exclusion of these and other sources of false-positive results is often useful for ruling out disease.