Metanephrine/Creatinine Ratio, 24-Hour Urine

What is this test?

This test measures metanephrine, a breakdown product of stress hormones called catecholamines, in urine collected for 24 hours. The result is compared with the amount of creatinine in the same collection, which helps account for differences in urine concentration.

Why might I need this test?

It may be used to evaluate recurring episodes of high blood pressure, severe headaches, sweating, rapid heartbeat, or episodes of apparent anxiety. The main purpose is to help determine whether these symptoms may be related to a catecholamine-producing tumor, such as pheochromocytoma or paraganglioma.

How is the test performed?

You collect all urine produced during a full 24-hour period in the container provided by the laboratory. The laboratory measures metanephrine and creatinine and reports the metanephrine-to-creatinine ratio.

How do I prepare for the test?

Begin the collection as instructed, usually in the morning after emptying your bladder, and include every urine sample for exactly 24 hours. Keep the container refrigerated if instructed, record the start and finish times, and return the collection promptly. Do not stop medications without advice from your clinician, because some medicines and foods can affect the results.