Effect of the somatostatin analog octreotide on gastric mucosal function and histology during 3 months of preoperative treatment in patients with acromegaly

Department of Endocrinology, Klinikum Benjamin Franklin, Freie Universitat, Berlin, Germany.

OBJECTIVE: To study the effects of the somatostatin analog octreotide on gastric mucosal function and histology during short-term (3 months) preoperative treatment in patients with acromegaly. DESIGN: Open design clinical study. METHODS: 10 patients were studied before treatment with octreotide (pre-tx), on day 1 of 300 microg octreotide/day (d300), after 1 week on 300 (w300), 600 (w600) or 1500 (wl500) microg octreotide/day, and after an additional 2.5 months on 1500 microg octreotide/day (M3). An 8h gastrin profile was obtained and ambulatory intragastric 23h pH-metry carried out at the indicated time points. Gastroscopy was performed at pre-tx and M3 and multiple mucosal biopsy specimens taken. RESULTS: The mean serum gastrin concentration at first declined during octreotide therapy to a nadir at w1500, then recovered despite ongoing therapy (probably in response to reduced gastric acidity) and was similar to pre-tx values at M3 (mean+/-S.E.: 87+/-26, 50+/-11 and 98+/-46ng/l for pre-tx, w1500 and M3 respectively; P<0.05, pre-tx vs w1500). Gastric acidity had also declined at d300(P<0.05, d300 vs pre-tx), then recovered (despite the increase in the octreotide dose), but declined again at M3 (mean pH (95% confidence interval): 2.4 (1.7-3.2), 3.3 (2.4-4.3), 2.6 (1.8-:3.5, n=8) and 2.9 (1.6-4.2, n=7) at pre-tx, d300, w1500 and M3 respectively). The gastrin concentration at M3, although similar to pre-tx values, remained inadequately low for the reduced gastric acidity. The reduction in gastric acidity was marked during the daytime (0900-2200 h; P<0.01, d300 vs pre-tx and P=0.028, M3 vs pre-tx). However, while the stimulated postprandial gastric acid secretion was reduced at d300 (P<0.01, d300 vs pre-tx) and at M3 (n=7; P=0.027, M3 vs pre-tx), fasting and preprandial acidity was not affected. During the night, gastric acidity was reduced from 2200 to 0300 h, but the reduction was less marked than during the daytime. Paradoxically, the physiological intermittent late nocturnal reduction in acidity ('pH peaks' (0300-0800 h)) was abolished rather than enhanced. No patient acquired new Helicobacter pylori infection. The mean gastritis scores for antrum and body (n=8, Sidney classification) increased marginally from 1.7 to 1.9 (chronicity) and from 0.7 to 0.9 (atrophy), while the activity score was slightly reduced from 1.2 to 1.0. CONCLUSIONS: Three months of preoperative octreotide treatment profoundly and persistently altered gastric mucosal function (gastrin suppression, reduced acidity), but caused only minor variations in the pre-existing gastritis scores.