Patient characteristics

The study was approved by the medical ethics committee of the University Medical Center Groningen, and all participants provided informed consent. In all patients, hormonal evaluation was carried out to determine hormonal deficiencies using pre-specified cut off values for hormonal deficiencies12. Before entry in the study, they had received replacement therapy with thyroid hormone and glucocorticoids if necessary. In case of suspected acromegaly, growth hormone excess was established by an elevated level of growth hormone during a glucose tolerance test and an elevated level of insulin-like growth hormone-1 in plasma. None of the patients was considered to have prolac-tinoma or Cushing’s disease. In all patients transsphenoidal surgery was carried out and the pituitary tumour classified as NFA or GHA on histopathological grounds (9 NFA and 3 GHA). In 6 of these patients (4NFA and 2 GHA) MRI and PET-images were performed 3 years after radiation therapy.