Acromegaly

    
      Re: Acromegaly
    


[ Follow Ups ] [ Post Followup ] [ The Neurology Forum ] [ FAQ ]



Posted by CCF Neurology on April 30, 1997 at 14:31:05:

In Reply to: Acromegaly posted by Candy on April 20, 1997 at 17:08:29:

: My stepbrother is undergoing tests right now and the
  doctors believe he may have Acromegaly.  The doctors
  seem very hesitate to give him a definite diagnosis as
  none of them have ever actually seen a case of it.
  We are trying to find out if there is a specialist in
  Acrogegaly in the Buffalo area.  I would appreciate
  hearing from anyone with any information on Acromegaly.
=======================================================
Hello, I found under www.endo.org a listing for acromegaly under an organization of www.niddk.nih.gov.  This information was copied from them and it is quite detailed. I hope you will find it helpful.  In addition there is an organization that you may call to get a recommendation for an endocrinologist in Buffalo.  If this is not helpful give the Cleveland Clinic Endocrinology department a call 1-800-CCF-CARE, and ask for the extension for endocrinology.  
Acromegaly is a hormonal disorder that results when the pituitary gland produces excess growth
hormone (GH). It most commonly affects middle-aged adults and can result in serious illness and
premature death. Once recognized, acromegaly is treatable in most patients, but because of its
slow and often insidious onset, it frequently is not diagnosed correctly.
The name acromegaly comes from the Greek words for "extremities" and "enlargement" and
reflects one of its most common symptoms, the abnormal growth of the hands and feet. Soft
tissue swelling of the hands and feet is often an early feature, with patients noticing a change in
ring or shoe size. Gradually, bony changes alter the patient's facial features: the brow and lower
jaw protrude, the nasal bone enlarges, and spacing of the teeth increases.
Overgrowth of bone and cartilage often leads to arthritis. When tissue thickens, it may trap
nerves, causing carpal tunnel syndrome, characterized by numbness and weakness of the hands.
Other symptoms of acromegaly include thick, coarse, oily skin; skin tags; enlarged lips, nose and
tongue; deepening of the voice due to enlarged sinuses and vocal cords; snoring due to upper
airway obstruction; excessive sweating and skin odor; fatigue and weakness; headaches;
impaired vision; abnormalities of the menstrual cycle and sometimes breast discharge in women;
and impotence in men. There may be enlargement of body organs, including the liver, spleen,
kidneys and heart.
The most serious health consequences of acromegaly are diabetes mellitus, hypertension, and
increased risk of cardiovascular disease. Patients with acromegaly are also at increased risk for
polyps of the colon that can develop into cancer.
When GH-producing tumors occur in childhood, the disease that results is called gigantism rather
than acromegaly. Fusion of the growth plates of the long bones occurs after puberty so that
development of excessive GH production in adults does not result in increased height. Prolonged
exposure to excess GH before fusion of the growth plates causes increased growth of the long
bones and increased height.
What Causes Acromegaly?
Acromegaly is caused by prolonged overproduction of GH by the pituitary gland. The pituitary is
a small gland at the base of the brain that produces several important hormones to control body
functions such as growth and development, reproduction, and metabolism. GH is part of a
cascade of hormones that, as the name implies, regulates the physical growth of the body. This
cascade begins in a part of the brain called the hypothalamus, which makes hormones that
regulate the pituitary. One of these, growth hormone-releasing hormone (GHRH), stimulates the
pituitary gland to produce GH. Another hypothalamic hormone, somatostatin, inhibits GH
production and release. Secretion of GH by the pituitary into the bloodstream causes the
production of another hormone, called insulin-like growth factor 1 (IGF-1), in the liver. IGF-1 is
the factor that actually causes the growth of bones and other tissues of the body. IGF-1, in turn,
signals the pituitary to reduce GH production. GHRH, somatostatin, GH, and IGF-1 levels in the
body are tightly regulated by each other and by sleep, exercise, stress, food intake and blood
sugar levels. If the pituitary continues to make GH independent of the normal regulatory
mechanisms, the level of IGF-1 continues to rise, leading to bone growth and organ enlargement.
The excess GH also causes changes in sugar and lipid metabolism and can cause diabetes.
Pituitary tumors
In over 90 percent of acromegaly patients, the overproduction of GH is caused by a benign
tumor of the pituitary gland, called an adenoma. These tumors produce excess GH and, as they
expand, compress surrounding brain tissues, such as the optic nerves. This expansion causes the
headaches and visual disturbances that are often symptoms of acromegaly. In addition,
compression of the surrounding normal pituitary tissue can alter production of other hormones,
leading to changes in menstruation and breast discharge in women and impotence in men.
There is a marked variation in rates of GH production and the aggressiveness of the tumor. Some
adenomas grow slowly and symptoms of GH excess are often not noticed for many years. Other
adenomas grow rapidly and invade surrounding brain areas or the sinuses, which are located near
the pituitary. In general, younger patients tend to have more aggressive tumors.
Most pituitary tumors arise spontaneously and are not genetically inherited. Many pituitary tumors
arise from a genetic alteration in a single pituitary cell which leads to increased cell division and
tumor formation. This genetic change, or mutation, is not present at birth, but is acquired during
life. The mutation occurs in a gene that regulates the transmission of chemical signals within
pituitary cells; it permanently switches on the signal that tells the cell to divide and secrete GH.
The events within the cell that cause disordered pituitary cell growth and GH oversecretion
currently are the subject of intensive research.
Non-pituitary tumors
In a few patients, acromegaly is caused not by pituitary tumors but by tumors of the pancreas,
lungs, and adrenal glands. These tumors also lead to an excess of GH, either because they
produce GH themselves or, more frequently, because they produce GHRH, the hormone that
stimulates the pituitary to make GH. In these patients, the excess GHRH can be measured in the
blood and establishes that the cause of the acromegaly is not due to a pituitary defect. When
these non-pituitary tumors are surgically removed, GH levels fall and the symptoms of acromegaly
improve.
In patients with GHRH-producing, non-pituitary tumors, the pituitary still may be enlarged and
may be mistaken for a tumor. Therefore, it is important that physicians carefully analyze all
"pituitary tumors" removed from patients with acromegaly in order not to overlook the possibility
that a tumor elsewhere in the body is causing the disorder.
How Common is Acromegaly?
Small pituitary adenomas are common. During autopsies, they are found in up to 25 percent of
the U.S. population. However, these tumors rarely cause symptoms or produce excessive GH or
other pituitary hormones. Scientists estimate that about 3 out of every million people develop
acromegaly each year and that 40 to 60 out of every million people suffer from the disease at any
time. However, because the clinical diagnosis of acromegaly often is missed, these numbers
probably underestimate the frequency of the disease.
How is Acromegaly Diagnosed?
If a doctor suspects acromegaly, he or she can measure the GH level in the blood after a patient
has fasted overnight to determine if it is elevated. However, a single measurement of an elevated
blood GH level is not enough to diagnose acromegaly, because GH is secreted by the pituitary in
spurts and its concentration in the blood can vary widely from minute to minute. At a given
moment, a patient with acromegaly may have a normal GH level, whereas a GH level in a healthy
person may be five times higher.
Because of these problems, more accurate information can be obtained when GH is measured
under conditions in which GH secretion is normally supressed. Physicians often use the oral
glucose tolerance test to diagnose acromegaly, because ingestion of 75 g of the sugar glucose
lowers blood GH levels less than 2 ng/ml in healthy people. In patients with GH overproduction,
this reduction does not occur. The glucose tolerance test is the most reliable method of confirming
a diagnosis of acromegaly.
Physicians also can measure IGF-1 levels in patients with suspected acromegaly. As mentioned
earlier, elevated GH levels increase IGF-1 blood levels. Because IGF-1 levels are much more
stable over the course of the day, they are often a more practical and reliable measure than GH
levels. Elevated IGF-1 levels almost always indicate acromegaly. However, a pregnant woman's
IGF-1 levels are two to three times higher than normal. In addition, physicians must be aware that
IGF-1 levels decline in aging people and may be abnormally low in patients with poorly
controlled diabetes mellitus.
After acromegaly has been diagnosed by measuring GH or IGF-1, imaging techniques, such as
computed tomography (CT) scans or magnetic resonance imaging (MRI) scans of the pituitary
are used to locate the tumor that causes the GH overproduction. Both techniques are excellent
tools to visualize a tumor without surgery. If scans fail to detect a pituitary tumor, the physician
should look for non-pituitary tumors in the chest, abdomen, or pelvis as the cause for excess GH.
The presence of such tumors usually can be diagnosed by measuring GHRH in the blood and by
a CT scan of possible tumor sites.
How is Acromegaly Treated?
The goals of treatment are to reduce GH production to normal levels, to relieve the pressure that
the growing pituitary tumor exerts on the surrounding brain areas, to preserve normal pituitary
function, and to reverse or ameliorate the symptoms of acromegaly. Currently, treatment options
include surgical removal of the tumor, drug therapy, and radiation therapy of the pituitary.
Surgery
Surgery is a rapid and effective treatment. The surgeon reaches the pituitary through an incision in
the nose and, with special tools, removes the tumor tissue in a procedure called transsphenoidal
surgery. This procedure promptly relieves the pressure on the surrounding brain regions and leads
to a lowering of GH levels. If the surgery is successful, facial appearance and soft tissue swelling
improve within a few days. Surgery is most successful in patients with blood GH levels below 40
ng/ml before the operation and with pituitary tumors no larger than 10 mm in diameter. Success
depends on the skill and experience of the surgeon. The success rate also depends on what level
of GH is defined as a cure. The best measure of surgical success is normalization of GH and
IGF-1 levels. Ideally, GH should be less than 2 ng/ml after an oral glucose load. A review of GH
levels in 1,360 patients worldwide immediately after surgery revealed that 60 percent had random
GH levels below 5 ng/ml. Complications of surgery may include cerebrospinal fluid leaks,
meningitis, or damage to the surrounding normal pituitary tissue, requiring lifelong pituitary
hormone replacement.
Even when surgery is successful and hormone levels return to normal, patients must be carefully
monitored for years for possible recurrence. More commonly, hormone levels may improve, but
not return completely to normal. These patients may then require additional treatment, usually with
medications.
Drug Therapy
Two medications currently are used to treat acromegaly. These drugs reduce both GH secretion
and tumor size. Medical therapy is sometimes used to shrink large tumors before surgery.
Bromocriptine (Parlodel