Encyclopedia of Health and Medicine

A
acromegaly A condition in which the PITUITARY
GLAND secretes excessive GROWTH HORMONE (GH),
causing the bones to thicken and become overgrown.
This excessive growth is most apparent in
the facial features and the extremities, especially
the jaw, brow, hands, and feet. Most commonly
acromegaly develops in midlife. When acromegaly
occurs before the growth plates in the long bones
of the arms and legs have fused, excessive height
results. Doctors call this gigantism rather than
acromegaly, though it is the same disease process.
When excessive secretion of GH takes place after
the growth plates have fused (generally after
PUBERTY), the bones enlarge by thickening and
spreading. This pattern of overgrowth results in
the distortions characteristic of the disorder.
A BOND ACROSS TIME
Some medical historians believe the biblical
giant Goliath and the sixteenth president of the
United States, Abraham Lincoln (1809–1865),
had in common the disorder of acromegaly. Both
were exceedingly tall for the time in which they
lived. Descriptions of Goliath and photographs
of Lincoln suggest the characteristic features of
acromegaly: overgrown facial features, excessive
height, and unusually large hands and feet. Lincoln’s
headaches and fatigue, widely known,
also were indications of acromegaly.
Though the small number of people doctors
diagnose with acromegaly gives the perception
this condition is rare, endocrinologists believe
acromegaly is much more common than those
numbers suggest. Acromegaly typically develops
over years to decades, with symptoms emerging
slowly and often nonspecifically. Many people
learn they have acromegaly during evaluation for
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other conditions that could account for their
symptoms, such as HYPERTENSION (high BLOOD PRES-
SURE) or DIABETES.
The most common cause of acromegaly is an
ADENOMA (noncancerous tumor) in the anterior
lobe of the pituitary gland, increasing the quantity
of cells that secrete GH. Occasionally an adenoma
or, rarely, an ADENOCARCINOMA (an adenoma that
has turned cancerous) that secretes GH and is
located elsewhere in the body, such as the gastrointestinal
tract (notably the PANCREAS) or the
LUNGS, is responsible. Growth hormone does not
itself cause growth but instead stimulates the LIVER
and other structures to produce other hormones,
known collectively as insulinlike growth factors,
or IGFs (sometimes called somatotropin mediators
or somatomedins), that increase the rate at which
cells divide. The most prominent of these is INSULIN
growth factor 1 (IGF-1). High GH secretion results
in excessive IGF-1 circulating in the BLOOD, which
becomes one of the clinical markers for making
the diagnosis.
Symptoms and Diagnostic Path
Often the earliest symptoms of acromegaly are
gradual changes in the hands and feet, especially
swelling of the palms and soles. A person may
need larger sizes of shoes or gloves than usual and
find that rings or watches no longer fit. Other
symptoms include
• frequent headaches and vision disturbances
• excessive sweating and body odor
• thickened, often darkened, SKIN and NAILS
• increasing space between the TEETH
• PAIN in the joints