The measurement of catecholamines (adrenaline, noradrenaline, and dopamine) is used in the diagnosis of pheochromocytoma (tumor of the adrenal medulla) and paragangliomas (peripheral nerve neoplasms). Both of these types of neoplasms can cause paroxysmal or chronic arterial hypertension. The measurement of catecholamines is also used in the monitoring of neuroblastoma patients.
Catecholamines (adrenaline or epinephrine, noradrenaline or norepinephrine, and dopamine) are found in the adrenal medulla, neurons, and brain. Their measurement is used to help diagnose, amongst other conditions, catecholamine-secreting tumors, such as pheochromocytoma.
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. Epinephrine 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 the kidneys.
Noradrenaline or norepinephrine is a hormone and neurotransmitter and is 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, 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 found in the brain, the sympathetic ganglia, the liver, the lungs, the intestine, and the retina. Dopamine is a product of dopa decarboxylation, acting by dilating the renal arteries, increasing the heart rate, and contracting the peripheral vascular system.
Plasma catecholamines reveal the balance between synthesis, release, uptake, catabolism, and excretion. 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 are standing upright than when they are supine. The absence of this difference may indicate dysfunction of the autonomic nervous system.
24-hour urine catecholamine levels are helpful in detecting paroxysmal secretions that can occur at any time during the day and may not be detected by measuring their plasma levels.
What Do Pathological Values Mean?
- Increase: Anger, electroconvulsive therapy, exercise, fear, ganglioblastoma (slight increase), ganglioneuroma (slight increase), hypoglycemia, hypotension, hypothyroidism, diabetic ketoacidosis, kidney disease, myocardial infarction (acute), neuroblastoma (slight increase), paragangliomas (slight increase), pheochromocytoma (continuous or intermittent increase), postoperative, prolonged exposure to cold, shock, stress, thyrotoxicosis. Medications: epinephrine, ethyl alcohol (ethanol, in large quantities), aspirin, decongestants, sympathomimetics, and tricyclic antidepressants.
- Decrease: Alzheimer's disease, high altitude living. Medications: barbiturates, clonidine, reserpine.
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.
