Urine metanephrine measurement is used for the diagnosis and laboratory documentation of catecholamine-secreting tumors such as pheochromocytomas and paragangliomas as well as confirmation of metanephrine plasma measurements.
Metanephrine measurement is used to evaluate adrenal function. Metanephrine is usually determined when a patient with hypertension is suspected of having pheochromocytoma, which is a tumor of the adrenal medulla. Less than 1% of hypertensive patients have pheochromocytomas. Metanephrines (normetanephrine and metanephrine) are the main substances that are formed in the adrenal medulla, released into the bloodstream, and excreted in the urine. These substances contain a catechol nucleus and an amine group and therefore belong to the catecholamines. Metanephrine and normetanephrine are metabolites of epinephrine and norepinephrine, respectively. Metanephrine and normetanephrine are then metabolized to vanillylmandelic acid (VMA).
The traditional method of testing is a 24-hour urine test (89-100% sensitivity) because blood testing has many interfering factors. Determination of metanephrines is the best test for the diagnosis of pheochromocytomas because metanephrine levels are not influenced by factors that influence catecholamine levels, (eg, postural changes, exercise, surgical stress) and at the same time have a better correlation with tumor size and fewer drug interventions than catecholamines.
Possible Interpretations of Pathological Values
- Increase: Adrenal tumors, brain tumors, ganglioneuroblastoma, ganglioneuroma, neuroblastoma, pheochromocytoma hypertension, malignant pheochromocytoma, pheochromocytoma, extensive metastases, myasthenia gravis, progressive muscular dystrophy, sepsis, severe stress
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
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