And It's About Time There Was Some Support For Cushing's!
Acromegaly
- An Overview
23 July 1999
by Troya Renee Yoder, used with
permission
as originally posted on Suite 101.com, Pituitary
Disorders
Acromegaly is a serious adult condition that results when the body is exposed to high levels of
growth hormone for a prolonged time. The progression of the disease is subtle and gradual, often resulting in misdiagnosis for years. When increased growth
hormone secretion occurs in childhood, it is clinically referred to as “gigantism”. Besides the debilitating nature of the disease,
acromegaly results in severe physical changes, and increased morbidity due to enlargement of the heart, liver, spleen, kidneys, and increased risk for cancerous colon polyps.
The increased growth hormone
secretion is most often due to a benignadenoma of the
pituitary
gland. In rare cases,
acromegaly is caused by tumors
of the pancreas, lungs or
adrenal glands, which either produce GH themselves, or produce growth hormone-releasing
hormone
(GHRD), which stimulates the
pituitary
to produce GH.
It is estimated that three out of a million people develop acromegaly each year. However, because of clinical misdiagnosis, it is thought that this number is an underestimation of the true number of cases.
SYMPTOMS
Enlarged hands, feet, and head (noticeable by an increase in shoe size, ring size, hat size)
Coarsening of facial features – enlarging jaw and facial bones, spreading teeth
Oral Glucose Tolerance Test This test is generally considered the most reliable method for diagnosing
acromegaly. The patient ingests 75grams of sugar glucose. In healthy people, this level of sugar glucose lowers blood glucose levels to less than 2ng/ml. However, in acromegalics, this reduction does not occur.
Measurement of IGF-1 levels Elevated IGF-1 levels are reliable indicators of
acromegaly.
Measurement of GH levels The measurement of
GH levels is not considered very reliable, as
GH secretion varies widely from moment to moment. Therefore, the test is only indicative of the level of
GH at the moment that the blood was drawn. Measurements of IGF- 1 levels are a more accurate predictor of
acromegaly, as increases in IGF-1 are more stable over a period of time.
The treatment for acromegaly involves normalization of
GH and IGF-1 levels.
Surgery – Surgical removal of pituitarytumors
provides immediate reduction in hormone secretions. However, there is risk of damaging the
pituitary, resulting in loss of all
pituitary
function.
Frontal Craniotomy – This type of surgery involves opening the skull to expose the
pituitary
and is rarely performed.
Transphenoidal Craniotomy - Incisions are made through the nose and behind the upper lip to access the
pituitary
gland. This is the surgery of choice as there are no visible scars, hospital stay is often two days, and it is very effective in reducing vision defects due to large
tumors. It is also especially effective in treating small
tumors.
Radiation – Radiation is often used as a follow-up to surgery if not all of the
tumor
cells were removed. Radiation is rarely the primary treatment option, as the effects on hormone levels and
tumor
size are often not noticeable for months to years.
Conventional Radiation – This type of treatment requires daily radiation treatments over 4-6 weeks. The radiation is not well focused and other brain tissues in and around the skull may be irradiated, and subsequently damaged.
Gamma Knife Radiosurgery
(Stereotactic Radiosurgery) - This is a more focused radiation treatment than conventional radiation, which reduces the risk of
hypopituitarism. It provides a large dose of radiation to a
tumor
so that when the tumor
cells divide, they die. As this method depends on the rate of cell division, symptoms may persist long after the radiation treatment.
Medications
Bromocriptine
(Parlodel) – Bromocriptine, or the newly released Dostinex, are oral medications that can reduce
GH secretion and even shrink some
tumors. However, they are effective in only half of
acromegaly patients.
Octreotide acetate (Sandostatin) – Sandostatin is a synthetic form of somatostatin and stops
GH production. It is usually injected subcutaneously 1-3 time a day and has proven effective in a large percentage of
acromegalics.
