Endocrine Abstracts

Long-acting somatostatin analogues normalize serum IGF-I levels in about 65% of acromegalic patients. Somatostatin analogs reduce GH secretion but also induce GH resistance of the liver because of low portal insulin levels; i.e. patients have a relative high GH level and a GH resistance of the liver which results in a relative low IGF-I action because of high IGFBP1 levels, but the other tissues still have normal GH sensitivity. One might predict that long-term follow-up of treated acromegalic patients is mandatory for find out the potential differential effects of the various medical treatment modalities. Especially as nowadays, the combination of somatostatin analogues and GH-R antagonists will be used by clinicians more frequently in order to decrease administration interval of the GH-R antagonist, as well as reduce its dose that is necessary to control disease activity in those acromegalic patients that do not respond to long-acting somatostatin monotherapy. The novel multiligand analogue SOM230 might increase the number of patients that can be biochemically controlled. SOM230 inhibits free IGF-I in a more sustained fashion compared to octreotide, implying longer duration of action. The superior action of octreotide compared with SOM230 in stimulating IGFBP-1 levels in acromegalic patients, suggests direct regulation of IGFBP-1 by somatostatin analogues via the somatostatin subtype 2 receptor. In summary, somatostatin analogs are the only compounds of which, at least in acromegaly, it has been shown that they reduce tumor size in those subjects that express sst on their pituitary tumors. However, the expression of sst on other tissues, involved in glucose metabolism, might have a negative influence on glucose metabolism on some patients