Acromegaly is a description for symptoms that are caused by the over production the human growth hormone (HGH). Acromegaly is more commonly called a pituitary adenoma, which is a benign tumor on the pituitary gland. “Acro” is Greek for tip or extremity and ‘mega’ is Greek for large. This disease affects the bones of the hands, feet jaw, nose and ribs. This disease can be caused by a tumor on other parts of the body (besides the pituitary gland) such as the lungs, pancreas or adrenal gland.
The symptoms of Acromegaly are due to the increase in the human growth hormone (HGH) and the benign tumor, pituitary adenoma. The symptoms can include:
• Enlarging hands and feet, which may involve soft tissue swelling, not just bone growth
• Increased space between the teeth
• Brow and lower jaw protrusion
• Arthritis and carpal tunnel syndrome
• Heart failure
• Visual disturbances, other than vision loss
• Loss of peripheral vision due to compression of the optic chasm
• Diabetes mellitus, also known as diabetes type I or type II
• Hypertension, also known as a high blood pressure
• Increased palm sweating and sebum (oil) production over the face, known as seborrhea.
The increased palm sweating and increase facial oil production are clinical indications of an increase in HGH produced by pituitary tumors. The symptoms may be used to evaluate hormone activity after tumor surgery, though this is more often monitored by blood tests.
In ninety percent of cases, Acromegaly is caused by the pituitary adenoma. The benign tumor on the pituitary gland tumor causes the over production of growth hormones. The tumors compress surrounding brain tissue, including the optic nerve as they grow. The expansion of the tumor causes headaches and vision abnormalities. The tumor can also affect the production of hormones other than the growth hormones causing impotence in men and menstruation and breast discharge in women.
Symptoms are dependent on the growth of the tumor. Some tumors grow slowly which cause symptoms to appear gradually causing a delay in diagnosis. When a tumor grows rapidly it can invade the sinuses.
In most cases, the pituitary adenoma starts spontaneously and is not genetically linked. Pituitary tumors may arise from a genetic alteration in a single cell which causes increased cell division and growth of the tumor. The genetic mutation or change in the cell is usually not present at birth, but begins later in life. The mutation occurs in a gene that controls the transmission of chemical signals within the pituitary cells. The mutated cells permanently turn on the mechanism that causes cells to divide and produce growth hormones. This mechanism that causes the pituitary cell growth to go haywire is currently the subject of intensive research.
Because Acromegaly can be caused by tumors on the lungs, pancreas and adrenal glands, it is important that any tumors removed from the pituitary gland be carefully inspected. This will confirm that the tumors are the cause of Acromegaly and not tumors from the pancreas, lung or adrenal glands.
Acromegaly is diagnosed by observation – because it is the extreme and unusual growth of the extremities. The pituitary adenoma is diagnosed via blood work and medical imaging – together. Most patients are diagnosed in adulthood.
The most sensitive lab test is IGF1. This involves GH level measurement two hours after a 75 gram glucose tolerance test. GH levels should be below 1 μg/L. Levels higher than this will be a positive for Acromegaly. Taking just a single value of GH levels will be inconclusive because it fluctuates greatly.
Other blood tests will measure the level of other pituitary hormones. These blood tests will detect the effects of the tumor, the secretion of hormones as well as the effect of the tumor on normal pituitary cells. TSH (thyroid stimulating hormone), gonadotropic hormones (FSH.LH), adreno-corticotropic (ACTH) hormone and prolactin are the hormones measured in the second blood test.
Treatment needs to be individualized for patients. There are currently three treatments available: surgery, radiation therapy and drug therapy. The objective of all treatments is to reduce the growth hormone production to the normal level and to relieve pressure of the pituitary adenoma on the brain.
Surgery is rapid and effective. If the tumor is small enough, the surgery is performed through an incision in the nose. The procedure is called trans-sphenoidal surgery. Successful surgery shows improvement in the facial appearance and soft tissue swelling in a few days. Patients with a growth hormone level below 40 ng/ml and tumors smaller than 10 mm are the most likely candidates for surgery.
Two medications are currently used to treat Acromegaly. Both drugs reduce growth hormone levels and secretion and tumor size. A newer medical treatment uses growth hormone receptor antagonists. This drug blocks the action of endogenous growth hormone molecules.
Radiation therapy has been used singularly and in combination with drug therapy or surgery. Commonly, it is prescribed when there is tumor tissue remaining after therapy; and used in conjunction with drug therapy.
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