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Effects of a chronic treatment with octreotide in patients with functionless pituitary adenomas
1Department of Medical-Surgical Endocrinology, University Federico II, School of Medicine, Naples, Italy.
Abstract:
The effects of a chronic treatment with octreotide were evaluated in 19 patients affected with functionless pituitary adenomas. Octreotide caused a significant decrease of GH and IGF-I levels in all the patients and no significant change in thyroid, adrenal and gonadal function. In contrast, during the therapy, the glucose response to an oral glucose tolerance test considerably increased and was delayed, while the insulin response decreased and was delayed. Serum alpha-subunit (alpha-SU) was above normal in 10 of 16 patients in which this evaluation was performed: octreotide caused a significant decrease (p < 0.01) of alpha-SU levels in 6 of these 10 patients. Octreotide did not induce any significant change in visual fields except in 1 patient, who had a great improvement of visual perimetry and a decrease of alpha-SU levels but unmodified CT scan features. In our series of patients, octreotide was ineffective in reducing tumor mass. The efficacy of octreotide might rely on the presence of somatostatin receptors on adenoma-cell membranes. Therefore patients with functionless adenomas to be treated with octreotide might be identified with pituitary scintiscan using the recently available labeled 111In-octreotide.
Insights
Octreotide treatment significantly lowered growth hormone (GH) and insulin-like growth factor-I (IGF-I) in patients with functionless pituitary adenomas. It also impacted glucose metabolism and reduced alpha-subunit levels in some patients.
Area of Science:
- Endocrinology
- Oncology
- Pharmacology
Background:
- Functionless pituitary adenomas lack specific hormone hypersecretion but can cause mass effects.
- Octreotide, a somatostatin analog, is used in treating various endocrine disorders.
Purpose of the Study:
- To evaluate the effects of chronic octreotide treatment on functionless pituitary adenomas.
- To assess hormonal changes, tumor markers, and clinical outcomes in patients receiving octreotide.
Main Methods:
- 19 patients with functionless pituitary adenomas received chronic octreotide treatment.
- Hormonal levels (GH, IGF-I, thyroid, adrenal, gonadal function, alpha-subunit), glucose tolerance tests, and visual fields were monitored.
- Tumor mass was assessed via CT scans.
Main Results:
- Octreotide significantly decreased GH and IGF-I levels in all patients.
- Glucose metabolism was altered, with increased and delayed glucose response and decreased, delayed insulin response.
- Serum alpha-subunit (alpha-SU) levels decreased significantly in 60% of patients with elevated levels.
- No significant change in tumor mass was observed, except for one patient with improved visual fields and decreased alpha-SU.
Conclusions:
- Octreotide effectively reduces GH and IGF-I in functionless pituitary adenomas and may decrease alpha-SU levels.
- The drug's efficacy may depend on somatostatin receptor presence on adenoma cells.
- Pituitary scintigraphy with 111In-octreotide could identify suitable candidates for octreotide therapy.