Indium-111 pentetreotide single-photon emission tomography in patients with TSH-secreting pituitary adenomas: Correlation with the effect of a single administration of octreotide on serum TSH levels |
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Authors: | M. Losa P. Magnani P. Mortini L. Persani S. Acerno E. Giugni C. Songini F. Fazio P. Beck-Peccoz M. Giovanelli |
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Affiliation: | (1) Department of Neurosurgery, IRCCS San Raffaele, via Olgetinna 60, I-20132 Milano, Italy;(2) INB-CNR Department of Nuclear Medicine, IRCCS San Raffaele, University of Milan, Italy;(3) Centro Auxologico Italiano IRCCS, University of Milan, Italy;(4) Institute of Endocrine Sciences, Istituto Clinico Humanitas, University of Milan, Italy |
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Abstract: | Few data are available on the visualization of somatostatin receptors in vivo in patients with thyrotropin (TSH)-secreting adenoma. We studied five patients with TSH-secreting adenomas using single-photon emission tomography (SPET) after administration of indium-111 pentetreotide. The intensity of111In-pentetreotide uptake by the tumours was correlated with the degree of TSH suppression after a single administration of 100 g octreotide s.c. Five patients (three women and two men) aged 27–46 years were investigated. Except for one patient with acromegaly, all had pure TSH-secreting inmours. One patient was previously untreated, while two had received octreotide, one antithyroid drugs, and one radioiodine. In all patients SPET demonstrated increased uptake of111In-pentetreotide by the pituitary adenoma. The target to non-target ratio (T/nT) of111In-pentetreotide uptake was higher than 10 in three patients. Administration of 100 g octreotide s.c. caused a significant reduction in TSH levels from 4.8±1.4 mU/l to a nadir of 3.1±1.1 mU/l after 6 h (P<0.001 by ANOVA). Suppression of TSH secretion ranged from 30% to 60% of the baseline value. The T/nT ratio showed a trend toward a direct relationship with the degree of TSH inhibition after acute octreotide administration (r=0.67;P=NS). Our study showed that111In-pentetreotide scan visualized somatostatin receptors in all five of the patients with TSH-secreting pituitary adenomas, confirming the frequent presence of somatostatin receptors in these rare tumours, even though the correlation with the TSH inhibition after a single administration of octreotide did not reach significance. |
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Keywords: | Pituitary neoplasm Thyrotropin Octreotide Hyperthyroidism Single-photon emission tomography |
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