The measurement of noradrenaline and other catecholamines in the urine is used as an adjunct to the diagnosis of pheochromocytoma and paragangliomas (along with the measurement of individual plasma catecholamines) as well as in the diagnosis and follow-up of patients with neuroblastoma and other similar tumors (along with the determination of vanillyl mandelic and homovanilic acid in the urine).
More information
Catecholamines (adrenaline or epinephrine, noradrenaline or norepinephrine, and dopamine) are produced in the adrenal medulla, neurons, and brain. Their measurement is used, among other things, to help diagnose catecholamine-secreting tumors, such as pheochromocytes.
Adrenaline, or epinephrine, is a hormone and neurotransmitter synthesized by the amino acid tyrosine and secreted after stimulation due to hypoglycemia, anxiety, fear, or anger. It acts during the body's fight-or-flight response, dilating the bronchioles, increasing the heart rate, increasing glycogenolysis to provide more glucose, and reducing peripheral resistance and blood flow to the skin and kidneys.
Noradrenaline, or norepinephrine, is a hormone, neurotransmitter, and the predominant catecholamine. The adrenal medulla secretes it in response to stimulation, and specific neurons also secrete it in the peripheral nervous system. Norepinephrine is synthesized from dopamine and, in the presence of tyramine, increases blood pressure through contraction of the peripheral vascular system, dilates the pupils of the eyes, and relaxes the gastrointestinal tract. It also acts as an intermediate molecule in the synthesis of epinephrine.
Dopamine is a neurotransmitter in the brain, sympathetic ganglia, liver, lungs, intestine, and retina. It is a product of dopa decarboxylation and acts by dilating the renal arteries, increasing the heart rate, and contracting the peripheral vascular system.
The levels of catecholamines reveal the balance between their synthesis, release, uptake, catabolism, and elimination. In phaeochromocytoma, the tumor secretes increased amounts of catecholamines, causing paroxysmal or persistent hypertension. Therefore, measuring catecholamine levels is most useful during or immediately after an episode of hypertension. In normal conditions, the concentration of epinephrine and norepinephrine should be higher when patients stand upright than when supine. The absence of this difference may indicate dysfunction of the autonomic nervous system.
24-hour urine catecholamine levels help detect paroxysmal secretions that can occur during the day but can not be detected by measuring their plasma levels.
Possible Interpretations of Pathological Values
- Increase: Adrenal cortex adenomas, burns, exercise (intense), ganglionoma, neuroblastoma, pheochromocytoma, epileptic seizures (tonic-clonic), catecholamine-secreting tumors, stress (anger, stress). Medications: Caffeine, ethyl alcohol (ethanol) (large quantities), reserpine (short-term use), sympathomimetics
- Decrease: Anorexia nervosa, familial dystonia, idiopathic and orthostatic hypotension. Medications: guanethidine sulfate, phenothiazines, reserpine (chronic use)
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting 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 analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
