Recent primary transnasal surgical outcomes associated with intraoperative growth hormone measurement in acromegaly

OBJECTIVE Since 1983, we have measured GH intraoperatively to improve the surgical outcome for acromegalic patients with GH secreting pituitary adenomas, Here, we present the recent results of primary surgery in patients with acromegaly to examine the effect of improved surgical techniques and experience, PATIENTS AND MEASUREMENT Intraoperative GH concentrations were measured in 78 consecutive acromegalic patients who had not previously undergone surgery between May 1992 and April 1994 (45 females and 33 males, age range, 21-70 years, mean, 47.1 +/- 1.3). All patients were followed for at least 3 years, Direct transnasal tumour extirpation was performed. Intraoperative GH measurements were assayed 0, 20 and 60 min after tumour removal. A plasma GH level less than or equal to 4.5 mu g/l at 60 min after initial tumour removal was used as a criterion of radical tumour removal, In cases with intraoperative plasma GH concentrations greater than or equal to 40 mu g/l prior to tumour resection, the half-life of the GH concentration at 20 min was used to assess completeness of tumour removal, In these cases, it was defined as having acheived a 50% reduction in plasma GH at 20 min compared to 0 min after tumour resection, To obtain intraoperative GH measurements, mild anaesthesia was continued for an average of 82 +/- 23 min. RESULTS Radical tumour removal was determined intraoperatively in 51 patients and subsequently confirmed in 50 patients (98.0%). In 18 of 27 patients with incomplete tumour removal, immediate reoperation was performed under continuous anaesthesia, In 11 of these 18 patients, endocrinological remission was achieved (14.1%; 11/78), None of the remaining nine patients who did not undergo secondary surgery achieved remission, Secondary surgery improved the remission rate from 85.7% (12/14) to 92.9% (13/14) in microadenomas and from 70.1% (38/54) to 88.9% (48/54) in non-invasive macroadenomas, Remission was not observed in patients with image-proven extrasellar extension. CONCLUSIONS Secondary surgery based on intraoperative GH measurement improves the outcome of tumour resection in patients with non-invasive GH secreting macroadenomas.