gms | German Medical Science

Objective: TSS is the treatment of choice for acromegaly. Cure is defined by normalization of age-related IGF-1 and sufficient suppression of GH in the oral glucose tolerance test (OGTT). We investigated, if early postoperative hormone testing gives reliable information whether complete resection of a tumor was achieved and compared these findings with further follow-up data.

Method: 50 patients underwent OGTT within a week after surgery, from April 2013 until June 2014. The aim is to get a one-year-follow-up of all patients. Up to now it was possible to gather a minimum-follow up of 6 months of 37 patients. 27 of these patients were surgically classified as complete resection, in 8 patients the intraoperative finding remained unclear regarding completeness, 2 patients underwent intended partial resection.

Results: 22 of 27 patients with “complete resection” showed adequate GH suppression below 1 µg/l in the early postoperative phase (82 %). Follow-up by hGH, IGF-1 and OGTT(GH) confirms the initial findings in all patients but one, who showed to be not in biochemical remission during extended follow-up. In 3 patients, the GH suppression was formally inadequate within a week, however, became physiological during follow-up (11 %), two patients with failed postoperative suppression, stayed biochemically acromegalic on follow-up (7 %). In the eight patients with unclear resection grade due to invasive growth, 4 patients showed adequate suppression of GH during early OGTT and during follow-up (50 %). The remaining 4 patients without postoperative suppression got into remission on follow-up (50 %). Of the two patients with incomplete resection one patient showed an adequate suppression but failed to get into remission on follow-up, the other patient showed no suppression of GH postoperatively as well as during follow-up, IGF-1 remained pathological.

Conclusions: These preliminary results show, that OGTT in the early postoperative stage is not sufficient to identify residual disease. However, OGTT seems efficient to predict cure in “positive” findings when the border to define suppression is at a value of 0,4 μg/l. So far, we lack a method to justify early repeat surgery in acromegaly in unclear cases. Moreover, these results have to be taken into account prior to initiation a medical or radiosurgical therapy after surgery.