Other tumors
In a few people, 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 (growth hormone-releasing hormone), the hormone that stimulates the pituitary to make GH. In these people, 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 nonpituitary tumors are surgically removed, GH levels fall and the symptoms of acromegaly improve.In people 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 people with acromegaly so as to not overlook the possibility that a tumor elsewhere in the body is causing the disorder. Diagnosis
If acromegaly is suspected, medical laboratory investigations followed by medical imaging if the lab tests are positive confirms or rules out the presence of this condition. IGF1 provides the most sensitive lab test for the diagnosis of acromegaly, and a GH suppression test following an oral glucose load, which is a very specific lab test, will confirm the diagnosis following a positive screening test for IGF1. A single value of the GH is not useful in view of its pulsatility (levels in the blood vary greatly even in healthy individuals).
Medications
Somatostatin analogues
The primary current medical treatment of acromegaly is to use somatostatin analogues – octreotide (Sandostatin) or lanreotide (Somatuline). These somatostatin analogues are synthetic forms of a brain hormone, somatostatin, which stops GH production. The long-acting forms of these drugs must be injected every 2 to 4 weeks for effective treatment. Most people with acromegaly respond to this medication. In many people with acromegaly, GH levels fall within one hour and headaches improve within minutes after the injection. Octreotide and lanreotide are effective for long-term treatment. Octreotide and lanreotide have also been used successfully to treat people with acromegaly caused by non-pituitary tumors.Somatostatin analogues are also sometimes used to shrink large tumors before surgery.Because octreotide inhibits gastrointestinal and pancreatic function, long-term use causes digestive problems such as loose stools, nausea, and gas in one third of people. In addition, approximately 25 percent of people with acromegaly develop gallstones, which are usually asymptomatic. In some cases, octreotide treatment can cause diabetes due to the fact that somatostatin and its analogues can inhibit the release of insulin. With an aggressive adenoma that is not able to be operated on, there may be a resistance to octreotide and in which case a second generation SSA, pasireotide, may be used for tumor control. However, insulin and glucose levels should be carefully monitored as pasireotide has been associated with hyperglycemia by reducing insulin secretion.