Urine Nor-metanephrine

Specimen Required

Fasting Required

Purpose of the Test

The urine nor-metanephrine test is used to evaluate patients with suspected or diagnosed pheochromocytoma, a rare tumor of the adrenal gland that secretes excess catecholamines (hormones involved in the “fight or flight” response). Elevated levels of normetanephrine in urine are a sensitive and specific indicator of pheochromocytoma.

When this test is required

The urine nor-metanephrine test is typically requested when a patient has symptoms suggestive of pheochromocytoma or has been diagnosed with pheochromocytoma and is being monitored for recurrence or response to treatment.

What the Test Detects

The urine nor-metanephrine test measures the levels of normetanephrine in urine. Normetanephrine is a metabolite of the catecholamine norepinephrine, which is produced by the adrenal gland and the sympathetic nervous system. Elevated levels of normetanephrine in urine are indicative of excessive catecholamine production, which can be caused by pheochromocytoma or other conditions.

Preparation for the Test

Before the test, the patient should avoid certain medications that can affect catecholamine levels, such as antidepressants, decongestants, and beta-blockers. The patient should also avoid strenuous exercise, alcohol, and foods high in tyramine (e.g., aged cheese, cured meats) for at least 24 hours before the test.

Sample Requirements

The urine nor-metanephrine test requires a random or 24-hour urine sample. The patient should collect all urine during the specified time period and store it in a clean, dry container. The sample should be kept refrigerated or on ice during collection and transport to the laboratory.

Additional Notes

The urine nor-metanephrine test is a useful tool for diagnosing pheochromocytoma, but it is not perfect. False positive and false negative results can occur, and additional testing may be necessary to confirm the diagnosis. The test should be interpreted in the context of the patient’s clinical presentation and other laboratory and imaging findings.

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