Use of intraoperative insulin assay for the localisation of insulinoma.

Abstract

The curative treatment for patients with insulinoma is the surgical removal of the tumour; however, these tumours are small and therefore their preoperative localisation using ultrasound and CT scans may be difficult. Intraoperative serum insulin measurements were used as an aid to the surgical management of seven unselected and consecutive presentations of insulinoma. In six of the seven cases we were able to demonstrate an increase in the peripheral serum insulin concentration between 3 and 5 min after manual examination of the tumour. In addition, there was a 50% decrease in concentration 10 min after removal of the tumour. We believe that intraoperative insulin measurements are of use in demonstrating the functionality of tumours localised by intraoperative ultrasound and surgical examination. In addition, they act as an indicator of the completeness of surgery post tumour excision.