Catecholamines are water-soluble chemical compounds that are synthesized in the body from the amino acid tyrosine. They are classified as adrenal hormones and, as such, are produced and released into the bloodstream in response to the stimulation of the preganglionic sympathetic nerves of the adrenal medulla. This event occurs in times of stress, whether due to emotional trauma, physical exertion, pain, or excitement. However, catecholamines production may also be triggered by low blood sugar. The predominantly occurring hormones are dopamine, norepinephrine, and epinephrine (formerly known as adrenaline).
As might be expected, there are certain biological reactions that accompany a copious release of catecholamines. While dopamine is one of the “feel good” hormones that promote a sense of euphoria, norepinephrine and epinephrine produce a very different experience since they act on the central nervous system and increase heart rate and blood pressure. In fact, these types of catecholamines are responsible for initiating the “fight or flight” response. However, it is interesting to note that norepinephrine and epinephrine are both synthesized as byproducts of dopamine production.
Abnormally elevated levels of circulating catecholamines may indicate toxicity and the presence of a medical disorder. For example, unusually high levels may be due to a deficiency of monoamine oxidase A, the agent that naturally degrades these hormones within minutes of release. High levels may also be associated with several rare disorders, such as ganglioneuroma and neuroblastoma. A chromaffin cell tumor affecting the adrenal glands can lead to a hypertensive disorder known as pheochromocytoma. In addition, numerous medications can increase catecholamine production, including nitroglycerin, levodopa, tetracycline, lithium, insulin, and caffeine.
If an adrenal hormone-related disorder is suspected, blood and urine tests may be performed, although urine samples usually provide more accurate readings. Measurements of catecholamines are given a value of nanograms per milliliter and are expressed as ng/100 mL. What is considered normal may vary between individuals and even testing facilities. Generally speaking, however, a normal level of norepinephrine is considered to be 60 ng/100 mL and epinephrine 20 ng/100 mL.
Patients are often advised to do everything possible to avoid emotionally charged or physically stressful situations prior to testing since these scenarios could impact catecholamine production. Certain foods should also be avoided for several days before testing. For example, caffeine-laden beverages, citrus fruits, bananas, chocolate, and vanilla all raise catecholamine levels. However, the patient should not cease taking any medication without consulting a physician, even if it is known to increase production of these adrenal hormones.
If catecholamine levels are found to be elevated, treatment is available. Generally, therapy is in the form of agents that suppress alpha or beta adrenoceptors located in smooth muscle tissue. These antagonists are commonly known as alpha-blockers and beta-blockers.