Encyclopedia of Health and Medicine

adrenal insufficiency 109
aldosterone. Some people experience disruptions
of the RAA hormonal matrix after kidney transplantation
because the transplanted kidney may
be slow to become fully functional. When this
occurs the person may need medications to help
regulate blood pressure and sodium–potassium
balance.
Though a separate structure, the adrenal gland
is in direct contact with the surface of the kidney.
One of the three arteries that delivers oxygenated
blood to the adrenal gland branches from the
renal ARTERY before the renal artery reaches the
kidney. NEPHRECTOMY (surgical OPERATION to
remove the kidney) can disturb this blood supply
and damage the adrenal gland. The risk of this is
highest with total nephrectomy, such as when
removing a kidney that has completely failed or
when radical nephrectomy (removal of the kidney,
URETER, adrenal gland, and substantial surrounding
tissue) is necessary to treat kidney
cancer. Though most people can adapt to having
only one adrenal gland just as they can adapt to
having only a single kidney, the loss of both adrenal
glands requires lifelong HORMONE THERAPY to
replace adrenal hormones (primarily cortisol and
aldosterone, the hormones of the adrenal cortex,
as other structures in the body also synthesize the
hormones the adrenal medulla produces).
Adrenal Gland Disorders
The most common disorder affecting the adrenal
glands is ADENOMA, a noncancerous tumor that
secretes excessive hormones of the division of the
adrenal gland (cortex or medulla) from which it
arises. Most commonly adrenal adenomas typically
develop in the zona fasciculata of the adrenal
cortex, causing excessive secretion of cortisol
(CUSHING’S SYNDROME). Adenomas that develop in
the zona glomerulosa cause excessive secretion of
aldosterone (HYPERALDOSTERONISM). PHEOCHROMOCY-
TOMA, a tumor (usually noncancerous) that
secretes epinephrine and norepinephrine, may
form in the adrenal medulla.
CONDITIONS AFFECTING THE ADRENAL GLANDS
ADDISON’S DISEASE
adrenal ADENOMA
ADRENAL INSUFFICIENCY
CUSHING’S SYNDROME
HYPOALDOSTERONISM
POLYGLANDULAR DEFICIENCY SYNDROME
PHEOCHROMOCYTOMA
For further discussion of the adrenal glands
within the context of the endocrine system’s
structure and function please see the overview
section “The Endocrine System.”
See also ADENOMA-TO-CARCINOMA TRANSITION;
AGING, ENDOCRINE CHANGES THAT OCCUR WITH.
adrenal insufficiency A condition, also called
secondary adrenal insufficiency, in which the
ADRENAL GLANDS fail to produce enough CORTISOL
because there is not enough ADRENOCORTICOTROPIC
HORMONE (ACTH) in the bloodstream. The cause
may be damage to the PITUITARY GLAND that prevents
it from synthesizing ACTH (such as a
tumor), or extended therapy with CORTICOSTEROID
MEDICATIONS (such as to treat some AUTOIMMUNE DIS-
ORDERS).
A tumor or its treatment may destroy the anterior
lobe of the pituitary gland, preventing it from
synthesizing ACTH. When this occurs permanent
HORMONE THERAPY becomes necessary to maintain
appropriate hormonal balance in the body, as the
pituitary gland is the body’s only source for ACTH.
During corticosteroid therapy, the high level of
circulating corticosteroid in the bloodstream signals
the HYPOTHALAMUS that no further release of
cortisol is necessary. This inhibits the release of
CORTICOTROPIN-RELEASING HORMONE (CRH), so there is
no signal to the pituitary gland to release ACTH.
In such circumstances adrenal insufficiency is
more likely to happen when the person abruptly
stops taking a corticosteroid medication rather
than tapering it, though it can occur whenever a
person takes corticosteroids for longer than four
weeks. Though the body nearly always returns to
normal HORMONE production in time, it is often
necessary for the person to take supplemental
hormone therapy in the interim.
Symptoms and Diagnostic Path
The symptoms of adrenal insufficiency are similar
to those of ADDISON’S DISEASE and include
• tiredness and fatigue
• HYPOTENSION (low BLOOD PRESSURE)
• loss of APPETITE and weight loss
• MUSCLE weakness
• irritability