Encyclopedia of Health and Medicine

adrenal glands 107
It is essential for the endocrinologist to distinguish
between Addison’s disease, which is primary adrenal
insufficiency (the dysfunction originates with the
adrenal cortex) and secondary adrenal insufficiency
(the dysfunction arises from inadequate ACTH, or
less commonly from inadequate CRH). Diagnostic
test results make this distinction clear.
Treatment Options and Outlook
Treatment consists of medications (HORMONE therapy)
to supplement or replace the adrenal hormones.
Endocrinologists commonly prescribe oral
hydrocortisone to supplement cortisol and fludrocortisone
to supplement aldosterone. Medication
dosages may change over time, and lifelong treatment
is necessary. Circumstances that stress the
body require additional medication, preferably in
advance of the stress, when possible, to avert an
Addisonian crisis. These circumstances include
PREGNANCY, labor and delivery, surgery, and serious
illness or injury.
Risk Factors and Preventive Measures
People who have other AUTOIMMUNE DISORDERS
such as HYPOTHYROIDISM or type 1 DIABETES have an
increased likelihood of developing the autoimmune
form of Addison’s disease. About 70 percent
of people who have Addison’s disease have the
autoimmune form. There are no known preventive
measures for Addison’s disease.
See also CHRONIC FATIGUE SYNDROME; POLYGLANDU-
LAR DEFICIENCY SYNDROME; STRESS AND STRESS MANAGE-
MENT; STRESS RESPONSE HORMONAL CASCADE.
adenoma A noncancerous tumor arising from
epithelial cells that typically forms within glandular
tissues or structures. An adenoma contains the
same cells as the gland from which it arises, causing
it to secrete the same hormones. The result is
an excess of the HORMONE within the BLOOD circulation,
which disrupts the endocrine balance to
cause an array of symptoms specific to the hormone
and its influences. Adenoma is a common
cause of many acquired endocrine disorders and is
usually treatable with surgery, medication, or
RADIATION THERAPY. Adenomas that do not cause
symptoms (asymptomatic) are exceedingly common,
and researchers estimate as many as 35 percent
of people have them.
The diagnostic path includes blood tests to
measure blood levels of the hormone and imaging
procedures to identify the adenoma’s location.
Because of the risk for an adenoma to become
cancerous, endocrinologists prefer to surgically
remove adenomas that cause symptoms. The surgery
can be straightforward or complex, depending
on the adenoma’s location. In some
circumstances the surgeon may need to remove
the entire affected gland to remove the tumor, or
may be unable to remove all of the adenoma.
Either circumstance may make it necessary for the
person to take long-term HORMONE THERAPY (with
removal of the entire gland) or to take medication
to suppress the tumor’s activity. Endocrinologists
often prefer to take a course of watchful waiting
with asymptomatic adenomas rather than initiating
any treatment.
See also ADENOMA-TO-CARCINOMA TRANSITION;
INTESTINAL POLYP.
adrenal glands A pair of endocrine glands,
sometimes called suprarenal glands, located one
above each kidney. The right adrenal gland is
clearly triangular in shape, and the left adrenal
gland has more of a crescent shape. Pumpkin colored,
each adrenal gland is about three inches
long and two inches deep, and rises above the kidney
one-half inch (left adrenal gland) to threequarters
inch (right adrenal gland). These
differences are due to the asymmetrical placement
of the KIDNEYS, with the left kidney placed higher
than the right in the abdomen.
The adrenal gland consists of two structurally
distinct divisions: the outer cortex and the inner
medulla. The adrenal cortex, a thick rindlike
structure that makes up about 90 percent of the
adrenal gland structure, encloses the adrenal
medulla. The adrenal cortex produces the steroid
hormones ALDOSTERONE and CORTISOL, as well as
ESTROGENS, PROGESTERONE, and TESTOSTERONE. The
fibrous, soft inner structure of the adrenal gland,
the adrenal medulla, secretes the peptide hormones
DOPAMINE, EPINEPHRINE, and NOREPINEPHRINE.
The most familiar function of the adrenal
glands is their management of the body’s physiologic
responses to stress, commonly identified as
the fight-or-flight reaction. In response to NERVE
and hormonal signals from the HYPOTHALAMUS, the