acromegaly

acromegaly, growth and metabolic condition characterized by enlargement of the skeletal extremities. Acromegaly results from the overproduction of growth hormone (somatotropin) after puberty, which typically is caused by a tumor of the pituitary gland or, rarely, a tumor elsewhere in the body. The condition is often associated with a type of growth in stature known as pituitary gigantism.

Symptoms

Acromegaly generally develops in middle-aged adults, and it progresses gradually, which can make early detection difficult. Symptoms include enlargement of the hands and feet, lengthening of the jaw and nose, deepening of the voice, thickening of the skin, and enlargement of most internal organs. Headache, excessive sweating, muscle weakness, sleep apnea, menstrual irregularities in women, erectile dysfunction in men, and high blood pressure are other manifestations.

As acromegaly progresses, symptoms may increase in severity. Some individuals, for example, may develop congestive heart failure, particularly when blood pressure becomes high. At times, excessive overgrowth of bone and cartilage involves the joints and causes pain. The bones may become thin and porous—a condition known as osteoporosis. Diabetes mellitus develops in 20 to 40 percent of affected individuals because excess growth hormone blocks the action of insulin. If the pituitary tumor enlarges, it can cause visual-field defects or evenblindness or paralysis of the eye muscles and can injure the posterior pituitary gland or the hypothalamus. Also, hemorrhage into the tumor can cause sudden loss of vision.

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Diagnosis and treatment

Acromegaly is diagnosed through a combination of clinical evaluation, hormone testing, and imaging studies. The key hormonal marker is insulin-like growth factor 1 (IGF-1), which is elevated in acromegaly and reflects long-term GH activity. To confirm excess GH production, an oral glucose tolerance test is performed; in healthy individuals, glucose suppresses GH levels, but in acromegaly, GH remains elevated. Once biochemical evidence is established, magnetic resonance imaging (MRI) of the pituitary gland is used to identify and locate the tumor responsible for GH overproduction. In the absence of a pituitary tumor, additional tests are performed to identify non-pituitary sources of excess GH, including chest and abdominal imaging and, occasionally genetic testing.

Treatment for acromegaly focuses on lowering excess GH levels and addressing the underlying cause. First-line treatment is usually transsphenoidal surgery, in which a pituitary tumor is removed by accessing the pituitary gland through the nose and sphenoid sinus; this is possible when the tumor is small and accessible. If surgery is not curative or feasible, radiation therapy may be employed. In addition, medications such as somatostatin analogs (octreotide or lanreotide), GH receptor antagonists (such as pegvisomant), and dopamine agonists (such as cabergoline) can be used to control hormone levels and sometimes shrink the tumor. Long-term monitoring of GH and IGF-1 levels is essential to ensure effective symptom control.