What are the other Names for this Test? (Equivalent Terms)
- Metanephrine and Normetanephrine Urine Test
What is Urine Metanephrines Test? (Background Information)
- Metanephrine and normetanephrine are intermediate breakdown products of the ‘fight-or-flight’ hormones epinephrine and norepinephrine (also called adrenaline and noradrenaline), respectively. The final breakdown product is vanillylmandelic acid (VMA)
- Collectively, metanephrine and normetanephrine may be referred to as “metanephrines” or “total metanephrines”
- Epinephrine and norepinephrine belong to a group of hormones, called catecholamines. Catecholamines are made in the adrenal glands. As the name implies, the 2 adrenal glands are situated atop (“ad-“ or “supra-“) each kidney (“renal”)
- Epinephrine and norepinephrine are normally released into the bloodstream, to prepare the body for physical stress. They affect nearly every tissue
- These two hormones stimulate the heart to beat faster, the lung bronchioles to expand, and the liver and fat cells to mobilize their energy stores. This increases the energy available to the body. It also facilitates its transportation to tissues that require it, such as the muscles and the brain
- Certain stimulants, such as amphetamines, exert their ‘pick-me-up’ effects by imitating epinephrine and norepinephrine
- Epinephrine is broken down step-wise; first into metanephrine and then into vanillylmandelic acid. Similarly, norepinephrine is broken down into normetanephrine, and then into VMA. VMA is excreted through urine
- Metanephrines may also appear in the urine during excessive catecholamine production, particularly in disease states, such as pheochromocytoma
- The Urine Metanephrines Test measures the levels of metanephrine and normetanephrine in urine. It is useful in detecting neuroendocrine disorders and cancers, such as pheochromocytoma
What are the Clinical Indications for performing the Urine Metanephrines Test?
The following, if present at rest, are clinical indicators for performing the Urine Metanephrines Test:
- Rapid heart rate
- High blood pressure
How is the Specimen Collected for Urine Metanephrines Test?
Following is the specimen collection process for Urine Metanephrines Test:
Sample required: Urine
Process: Urine is collected in a sterile container, often multiple times within a 24-hour period.
Preparation required: No special preparation is needed prior to the test.
What is the Significance of the Urine Metanephrines Test Result?
Elevated levels of urine metanephrines may indicate:
- Adrenal gland disorder or a tumor, such as pheochromocytoma
- Excessive and chronic stress
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
- Adrenal gland tumors are usually not cancerous, implying that they do not usually spread to other tissues (a process known as metastasis)
- Certain factors interfere with the results of this test and these include foods that contain methylxanthine, such as coffee, chocolate, and tea
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.