The predictive value of an acute octreotide suppression test in patients with acromegaly

Acromegaly is a rare chronic disorder that is in 95% of cases caused by growth hormone (GH) secreting pituitary tumors. Endonasal transphenoidal surgery is usually considered the first line of treatment, followed by medical therapy for residual disease. The long-acting somatostatin (SA) analogues have an important role in the medical treatment of these patients. SA exert their biological effects by activating somatostatin receptors (SSTR). The predominant types of SSTR receptors in GH-secreting pituitary tumors are subtypes 2 (SSTR2) and 5 (SSTR5). The efficacy of somatostatin analog therapy (SAT) is determined by its effect on tumor shrinkage which is reported to be between 20 and 50%. Approximately 10-30% of GH-secreting pituitary tumors are resistant to SA because of variable or reduced tumoral expression of