Endocrine Abstracts

The outcome of parathyroid surgery is often not clear for at least 24 hours after an operation. Frozen section is not always helpful in distinguishing between adenoma and hyperplasia. Minimally invasive surgical techniques are being refined so the need for perioperative assurance about the effects of surgery has increased. PTH assays have been adapted to give results in less than 20 minutes. We have tested the value of intraoperative PTH measurements in 10 surgical cases undergoing parathyroidectomy. A single adenoma was removed from 7 patients. Three patients had multi-glandular disease (2 MEN 1, 1 X linked hypophosphataemia). Blood samples were taken at the onset of surgery, at the time of tumour resection, at 5 minute intervals following removal of the tumour. Plasma was separated by centrifugation. PTH was measured on an Immulite Turbo intact PTH assay (Diagnostic Products Corp [DPC], CA, USA, a solid phase, two-site, chemiluminescent enzyme immunometric design. PTH concentrations fell by 50% over 5 minutes after excision of parathyroid adenomas. Some results had fallen dramatically even before the tumour was removed presumably due to devascularisation during dissection. In 3 cases undergoing re-exploration surgery for hyperplasia, the reduction in PTH concentration was less than 50% and further exploration revealed another parathyroid that was removed. PTH concentrations increased during the second phase of the operation in some cases but fell on removal of a second parathyroid. PTH results were available within 40 minutes of excision of an adenoma using the Turbo instrument located in the laboratory. All frozen sections confirmed parathyroid tissue was removed. Serum calcium was normalised in all 10 cases. These findings suggest that intraoperative PTH measurement is an important adjunct to parathyroid surgery.