The adrenal glands sit on top of the kidneys and are sometimes called suprarenal glands. The adrenal gland is actually two glands that are fused together into one gland. Their triangular shape is composed of two main layers as a result: cortex and medulla.
The adrenal medulla produces two main chemicals called catecholamines: epinephrine (also called adrenaline) and norepinephrine. Both of these chemicals are involved in regulation of the nervous system. Epinephrine controls the short-term stress response (aka fight-or-flight response) with the help of norepinephrine, which is also involved in the regulation of mood.
The outer part of the adrenal gland, also called the adrenal cortex, produces steroid hormones that are involved in regulating a number of different body functions. Mineralocorticoids (such as aldosterone) help regulate the salt levels in the body by controlling the absorption and excretion of salt and water in the kidneys which is important in the regulation of blood pressure. Glucocorticoids (such as cortisol) regulate sugar and fat stores within the body, act as a strong anti-inflammatory force, and play an important role in fetal development, particularly in lung maturation. The adrenal cortex also produces several sex steroid hormones, including androgens (critical for male sexual development) and precursors to estrogen (critical for female sexual development).
Tumors of the adrenal glands arise from the cortex or the medulla part of the adrenal gland. Most are found during CT scans or other imaging for various reasons. Others are found due to the effects of the oversecretion of the chemicals or hormones they produce.
- Steroids: Excess secretion of the steroid hormones produce a Cushing’s syndrome
- Aldosterone: Excess secretion of aldosterone produce a Conn’s syndrome
- Catecholamines: Excess secretion of catecholamines produce a pheochromocytoma
A benign tumor called an adrenal adenoma is the most common and is sometimes called an “incidentaloma” if it is not causing any hormonal or chemical oversecretions. However, there is a newer line of research which indicates these are not to be taken lightly and may be a result of other endocrine malfunctions. Marc Slawik and Martin Reincke write in Endotext.com:
In a study patients with incidentalomas who were suffering from subclinical Cushing´s syndrome (SCCS) were significantly more obese (17). In addition, patients with incidentalomas more frequently suffer from diabetes mellitus type 2 (2, 5) and it has been postulated that in these individuals hyperinsulinism leads to an increased proliferation of adrenal cells (25). Taking these findings together there seems to be a clear association of incidentalomas with features of the metabolic syndrome (obesity, arterial hypertension, NIDDM, dyslipidemia, dyscoagulation).
Just this week I linked to a news article which said:
The study, lead by Dr. Leslie Eldeiry, a clinical instructor at Harvard Medical School, which was conducted at Harvard Vanguard Medical Associates, found that"only 30 percent of patients underwent biochemical evaluation for adrenal hyperfunction," which is the production of excessive amounts of hormone.
In 2002, the National Institutes of Health released guidelines recommending hormonal evaluation of all incidentally discovered adrenal masses. Despitethe 2002 NIH recommendations, only 30 percent of patients were properly tested. Moreover only 18 percent of patients in the study who did not see an endocrinologist with adrenal nodules had hormonal testing.
The most common malignant tumors found in the adrenal gland are tumors that come from cancer cells that have metastasized (or spread) from other parts of the body to the adrenal gland through the blood stream.
Rarely, cancers can arise directly within the adrenal glands themselves. Cancers of the adrenal cortex are called adrenal cortical cancers. Functioning adrenal cortical cancers (they secrete excess steroid hormones) are more common than non-functioning cancers.
The most common cancer of the medulla are pheochromocytomas. In children, neuroblastoma tumors can develop within the adrenal medulla.
On my next installment, I'll start talking about some of the testing that is done and what hormones/steroids/chemicals are measured.