Journal of Clinical Endocrinology & Metabolism, Vol 75, 1318-1325, Copyright © 1992 by Endocrine Society

ARTICLES

Chronic somatostatin analog administration in patients with alpha- subunit-secreting pituitary tumors

L Katznelson, DS Oppenheim, JF Coughlin, B Kliman, DA Schoenfeld and A Klibanski
Neuroendocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston 02114.

Glycoprotein hormone-producing (GPH) pituitary adenomas represent approximately 25% of all pituitary tumors. Elevated serum levels of intact GPHs or their free alpha- and beta-subunits have been demonstrated in patients with such tumors, and isolated hypersecretion of alpha-subunit has been reported to occur in 7% of patients. Somatostatin has been shown to decrease GPH subunit levels in cultured adenoma cells in vitro, and somatostatin receptors have been identified on the cell membranes of these tumors. We, therefore, investigated the effect of chronic somatostatin analog administration on hormone production and tumor size in six patients with GPH-producing macroadenomas and elevated serum alpha-subunit levels. Patients initially received native somatostatin as an iv 250-micrograms bolus at 0800 h, followed by a constant infusion of 2 mg over 4 h, and serum alpha-subunit concentrations were measured at 30-min intervals after baseline sampling for a total of 9 h. Patients then received a somatostatin analog, octreotide (100 micrograms, twice daily, sc) for 8 weeks. Serum alpha-subunit levels were determined weekly at 30-min intervals before and for 4 h after the 0800 h octreotide dose. Pituitary magnetic resonance imaging scans and visual field testing were assessed before and after the study. During the 4-h somatostatin infusion, four patients had a significant decrease in alpha-subunit levels (P < 0.05). During the 8-week chronic octreotide administration period, two patients had significant decreases in alpha-subunit levels of 34.6% and 26.7% (P = 0.03 and 0.01, respectively). One of these two patients had a small reduction in tumor size. Two patients whose serum alpha-subunit level did not significantly change while receiving octreotide had a reduction in tumor size or definite improvement in visual field abnormalities. Three patients received a maximum octreotide dose of 250 micrograms, three times daily. In one patient, there was a significant decrease in alpha-subunit levels by 45% (P = 0.0001) in association with a marked improvement in visual field abnormalities. In another such patient, continued administration of octreotide to a maximum dose of 250 micrograms, three times daily, was associated with a marked reduction in tumor size. Of the four patients who demonstrated significant decreases in alpha-subunit concentrations during the initial somatostatin infusion, three patients had a significant reduction in alpha-subunit levels while receiving octreotide. One patient who did not have a decrease in alpha-subunit levels during the somatostatin infusion demonstrated a small decrease in tumor size during higher dose octreotide treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				O. M. Dekkers, A. M. Pereira, and J. A. Romijn Treatment and Follow-Up of Clinically Nonfunctioning Pituitary Macroadenomas J. Clin. Endocrinol. Metab., October 1, 2008; 93(10): 3717 - 3726. [Abstract] [Full Text] [PDF]

				T. Florio, F. Barbieri, R. Spaziante, G. Zona, L. J Hofland, P. M van Koetsveld, R. A Feelders, G. K Stalla, M. Theodoropoulou, M. D Culler, et al. Efficacy of a dopamine-somatostatin chimeric molecule, BIM-23A760, in the control of cell growth from primary cultures of human non-functioning pituitary adenomas: a multi-center study Endocr. Relat. Cancer, June 1, 2008; 15(2): 583 - 596. [Abstract] [Full Text] [PDF]

				G. F Taboada, R. M Luque, W. Bastos, R. F C Guimaraes, J. B Marcondes, L. M C Chimelli, R. Fontes, P. J P Mata, P. N. Filho, D. P Carvalho, et al. Quantitative analysis of somatostatin receptor subtype (SSTR1-5) gene expression levels in somatotropinomas and non-functioning pituitary adenomas Eur. J. Endocrinol., January 1, 2007; 156(1): 65 - 74. [Abstract] [Full Text] [PDF]

				E. Ferrante, M. Ferraroni, T. Castrignano, L. Menicatti, M. Anagni, G. Reimondo, P. Del Monte, D. Bernasconi, P. Loli, M. Faustini-Fustini, et al. Non-functioning pituitary adenoma database: a useful resource to improve the clinical management of pituitary tumors Eur. J. Endocrinol., December 1, 2006; 155(6): 823 - 829. [Abstract] [Full Text] [PDF]

				M. C. Zatelli, D. Piccin, A. Bottoni, M. R. Ambrosio, A. Margutti, R. Padovani, M. Scanarini, J. E. Taylor, M. D. Culler, L. Cavazzini, et al. Evidence for Differential Effects of Selective Somatostatin Receptor Subtype Agonists on {alpha}-Subunit and Chromogranin A Secretion and on Cell Viability in Human Nonfunctioning Pituitary Adenomas in Vitro J. Clin. Endocrinol. Metab., October 1, 2004; 89(10): 5181 - 5188. [Abstract] [Full Text] [PDF]

				D. C. Danila, J. N. S. Haidar, X. Zhang, L. Katznelson, M. D. Culler, and A. Klibanski Somatostatin Receptor-Specific Analogs: Effects on Cell Proliferation and Growth Hormone Secretion in Human Somatotroph Tumors J. Clin. Endocrinol. Metab., July 1, 2001; 86(7): 2976 - 2981. [Abstract] [Full Text] [PDF]