Acromegaly is the result of sustained, elevated growth hormone release by a somatotrophic adenoma (a benign tumor of the pituitary gland that stimulates body growth). Growth hormone is essential during puberty and is responsible for the growth spurt. After this, growth hormone production drops down to very low but important levels. Pituitary adenomas can secrete growth hormone causing acromegaly in adults and gigantism in pre-pubescent children, in whom the bone growth plates are open, causing further elongation of the long bones. Most growth hormone effects are mediated through insulin-like growth factor-1 (IGF-1), which is produced by the liver.
In acromegaly, elevated growth hormone causes an increase in shoe and ring size, enlargement of the mandible leading to an underbite, frontal bossing, and enlargement of the nose.
These changes are usually very gradual and may be missed by the patient and their family for many years. Soft tissue within the body can also enlarge, causing increased snoring, sleep apnea, chronic sinus problems, radiculopathy from nerve root entrapment (i.e., carpal tunnel syndrome), joint pain and stiffness, increase in sweating (hyperhydrosis), and even changes in voice and body odor.
Patients with acromegaly may have accelerated cardiovascular disease and thickening (hypertrophy) of the heart muscles, diabetes, and an increased risk of colon polyps. Many of the changes related to acromegaly reverse once the growth hormone and IGF-1 levels are normalized; however, the changes in bone structure do not reverse.
The principal treatment for acromegaly is transsphenoidal pituitary surgery to remove the adenoma. However, because acromegaly can develop very gradually, tumors are often large and have invaded into surrounding structures by the time symptoms occur. For patients with areas of residual tumor, radiotherapy or medical management may be necessary.
The primary goal for medical treatment of acromegaly is normalization of growth hormone levels. The drug octreotide inhibits growth hormone release. Long-term treatment can result in normalized levels of growth hormone and IGF-1 in over 50% of patients and amelioration of symptoms. A newer drug, pegvisomant, binds to growth hormone receptors and can normalize the IGF-1 levels in 90% of patients. Dopamine agonists have also been used, although growth hormone normalization occurs in 15-30% of patients using this treatment.