• Antongiulio Faggiano, Lidice Brandao Tavares, Libuse Tauchmanova, Francesco Milone, Gelsomina Mansueto, Valeria Ramundo, Maria Laura Del Basso De Caro, Gaetano Lombardi, Gaetano De Rosa, and Annamaria Colao.
• Department of Molecular and Clinical Endocrinology and Oncology, Federico II University of Naples, Naples, Italy. afaggian@unina.it
• Clin. Endocrinol. (Oxf). 2008 Nov 1; 69 (5): 756-62.

BackgroundIn patients with multiple endocrine neoplasia type 1 (MEN1), expression of somatostatin receptor (SST) in parathyroid adenomas and effectiveness of therapy with somatostatin analogues on primary hyperparathyroidism (PHP) have been scarcely investigated.ObjectiveTo evaluate the effects of depot long acting octreotide (OCT-LAR) in patients with MEN1-related PHP.PatientsEight patients with a genetically confirmed MEN1, presenting both PHP and duodeno-pancreatic neuroendocrine tumours (NET), were enrolled.DesignThe initial treatment was OCT-LAR 30 mg every 4 weeks. This therapy was established to stabilize the duodeno-pancreatic NET before to perform parathyroidectomy for PHP. Before OCT-LAR therapy, a SST scintigraphy was performed in all patients. SST subtype 2A immunohistochemistry was performed on parathyroid tumour samples from three patients undergone parathyroidectomy after OCT-LAR therapy.MeasurementsSerum concentrations of PTH, calcium and phosphorus as well as the 24-h urine calcium : creatinine ratio and the renal threshold phosphate concentration were evaluated before and after OCT-LAR.ResultsAfter OCT-LAR therapy, hypercalcaemia and hypercalciuria normalized in 75% and 62.5% of patients, respectively, and serum phosphorus and renal threshold phosphate significantly increased. Serum PTH concentrations significantly decreased in all patients and normalized in two of them. SST subtype 2A immunostaining was found in all parathyroid adenomas investigated, while SST scintigraphy showed a positive parathyroid tumour uptake in three of eight patients (37.5%).ConclusionSix months of OCT-LAR therapy controlled hypercalcaemia and hypercalciuria in two-thirds of patients with MEN1-related PHP. Direct OCT-LAR effects mediated by binding to SST expression on parathyroid tumour cells are likely the main mechanism to explain the activity of this compound on calcium and phosphorus abnormalities in MEN1 PHP.

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