Metanephrine, 24 Hours Urine

Metanephrine, 24 Hours Urine

What it is

The Metanephrine, 24 Hours Urine test measures the total amount of metanephrines (metanephrine and normetanephrine) excreted in urine over a 24-hour period. Metanephrines are breakdown products of adrenaline (epinephrine) and noradrenaline (norepinephrine). Elevated levels may indicate the presence of catecholamine-secreting tumors such as pheochromocytomas or paragangliomas.

Uses

This test is primarily used to help diagnose adrenal and extra-adrenal tumors that produce excess catecholamines. It is also used when patients present with unexplained high blood pressure, repeated episodes of palpitations, sweating, and severe headaches. Compared to plasma metanephrine testing, the 24-hour urine test helps reduce false positives by averaging hormone levels over a full day.

Symptoms That May Lead to the Test

Doctors may order this test if you experience symptoms such as sudden spikes in blood pressure, rapid heartbeat, excessive sweating, tremors, anxiety, chest pain, headaches, or unexplained weight loss. It may also be recommended if imaging studies suggest an adrenal or paraganglionic mass.

Abnormal Results

High Urinary Metanephrines: Suggests the possibility of pheochromocytoma, paraganglioma, or another disorder causing excess catecholamine production. Certain medications, stress, and dietary factors can also elevate results.

Normal or Low Urinary Metanephrines: Suggests no biochemical evidence of catecholamine-producing tumors. However, repeat testing or plasma metanephrine measurement may be required if suspicion remains high.

Risks

The test requires collecting all urine produced over 24 hours. While non-invasive and safe, the main challenge is proper sample collection and storage to ensure accurate results.