Encyclopedia of Health and Medicine

110 The Endocrine System
A history of recent (within several months)
corticosteroid therapy is a strong indicator for
adrenal insufficiency. The diagnostic path includes
tests to measure the levels of potassium, sodium,
GLUCOSE, cortisol, and ACTH in the blood. Other
procedures typically include ACTH- and CRHstimulation
tests to assess the body’s ability to produce
cortisol. The endocrinologist may conduct
diagnostic imaging procedures such as MAGNETIC
RESONANCE IMAGING (MRI) or COMPUTED TOMOGRAPHY
(CT) SCAN to visualize and evaluate the pituitary
gland and adrenal glands.
DISTINGUISHING FEATURES OF ADRENAL
INSUFFICIENCY AND ADDISON’S DISEASE
Adrenal Insufficiency
low ACTH
normal SKIN color
normal BLOOD potassium
level
normal blood sodium level
normal blood GLUCOSE level
normal ALDOSTERONE
production
Addison’s Disease
normal ACTH
areas of hyperpigmentation
elevated blood potassium
level (HYPERKALEMIA)
low blood sodium level
(HYPONATREMIA)
low blood glucose level
(HYPOGLYCEMIA)
deficient aldosterone
production
Treatment Options and Outlook
Treatment consists of medication (hormone therapy),
typically oral hydrocortisone, to supplement
adrenal production of cortisol until the pituitary
gland returns to normal ACTH production. Most
adrenal insufficiency resolves within a year of
onset. When the cause of the adrenal insufficiency
is permanent, such as damage to or destruction of
the anterior lobe of the pituitary gland, permanent
hormone therapy becomes necessary as well. During
treatment it is important for the person to
remain vigilant for signs of adrenal crisis, which
requires emergency medical treatment. Circumstances
that increase the risk for adrenal crisis
include physiologic stress such as trauma, INFEC-
TION, surgery, and PREGNANCY and CHILDBIRTH.
Risk Factors and Preventive Measures
The leading risk factor for adrenal insufficiency is
corticosteroid therapy. The typical approach is to
taper the corticosteroid DOSE gradually, to allow
the body’s normal hormonal mechanisms to
resume. Abruptly stopping a corticosteroid medication
after taking it for four weeks or longer
greatly increases the risk for adrenal insufficiency.
See also CHRONIC FATIGUE SYNDROME; POLYGLANDU-
LAR DEFICIENCY SYNDROME; STRESS AND STRESS MANAGE-
MENT.
adrenocorticotropic hormone (ACTH) A peptide
HORMONE, also called corticotropin, the anterior
lobe of the PITUITARY GLAND produces to
stimulate the adrenal cortex of the ADRENAL GLANDS
to synthesize and release CORTISOL. ACTH is one of
the hormones in the STRESS RESPONSE HORMONAL
CASCADE. The HYPOTHALAMUS releases the hormone
CORTICOTROPIN-RELEASING HORMONE (CRH) to stimulate
the pituitary’s synthesis of ACTH. When cortisol
levels reach the appropriate level in the
bloodstream the hypothalamus shuts down its
release of CRH and the pituitary gland subsequently
ceases ACTH production until cortisol levels
again drop. This cycle is ongoing as cortisol has
numerous actions within the body, notably to
facilitate carbohydrate and fat METABOLISM and
suppress INFLAMMATION and other aspects of the
IMMUNE RESPONSE.
For further discussion of ACTH within the context
of the endocrine system’s structure and function
please see the overview section “The
Endocrine System.”
See also ALDOSTERONE; FOLLICLE-STIMULATING HOR-
MONE (FSH); GROWTH HORMONE (GH); LUTEINIZING HOR-
MONE (LH); PROLACTIN; THYROID-STIMULATING HORMONE
(TSH).
aging, endocrine changes that occur with The
endocrine system initiates many of the significant
changes that mark the phases of life, from CONCEP-
TION to old age. Because critical endocrine processes
slow with advancing age, many people believe the
endocrine system holds the secrets to aging and
thus the answers to slowing or preventing the
changes that occur in the body that cause aging.
The most obvious endocrine changes that occur
with age are those that regulate sexual maturation
and reproduction. The onset of PUBERTY heralds the
transition from childhood to adulthood and nearly
every ENDOCRINE GLAND plays a role. The HYPOTHAL-
AMUS steps up production and secretion of
GONADOTROPIN-RELEASING HORMONE (GNRH), GROWTH