Endocrine Abstracts

Transsphenoidal surgery is the treatment of choice for acromegaly. Cure is defined by normalization of age-related IGF1 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.

So far, 22 patients underwent OGTT within a week after surgery, starting April 2013. Sixteen patients were surgically classified as complete resection, in five patients the intraoperative finding remained unclear regarding completeness, one patient underwent partial resection.

Eleven of 16 patients with ‘complete resection’ showed adequate GH suppression below 1 μg/l in the early postoperative phase (69%). Follow-up by IGF1 and OGTT is available in seven patients so far, which confirms the initial findings. In three patients, the GH suppression was formally inadequate within a week, however, became physiological during further follow-up (19%). In the five patients with unclear resection grade due to invasive growth, two showed adequate suppression of GH during early OGTT and during follow-up (40%). In the remaining 3 patients, follow-up is pending.

The patient with incomplete resection showed no suppression of GH postoperatively as well as during follow-up, IGF1 remained pathological.

These preliminary results show, that OGTT in the early postoperative stage is not sufficient to identify residual disease, as previously shown by Kristof et al., 2002. However, OGTT seems efficient to predict cure in ‘positive’ findings. 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 therapy after surgery.