Impact of primary surgery on pituitary function in patients with non-functioning pituitary adenomas -- a study on 721 patients.

INTRODUCTION: The aim of this study was to define the impact of surgery on pituitary function in a large consecutive series of patients harbouring non-functioning pituitary adenomas. MATERIALS AND
METHOD: Between December 1982 and December 2000, a total of 822 patients underwent primary surgery in the authors' department. In 721 cases a complete set of endocrinological data was available. Functions of the pituitary-gonadal, pituitary-thyroid and pituitary-adrenal axes were assessed immediately before surgery and again one week, 3 months and 1 year after the operation, utilizing standardized tests and commercially available assays.
RESULTS: There was some degree of pre-operative hypopituitarism in 561 (85%) and 53 (86.3%) of the patients belonging to the transsphenoidal and the transcranial groups, respectively. Prior to transsphenoidal [transcranial] surgery, 163 (31%) [34 (55.7%)] of the patients had secondary adrenal deficiency, 463 (76.6%) [49 (89%)] had hypogonadism and 105 (19.1%) [14 (25.4%)] were hypothyroid. Preoperatively, prolactin levels were mildly elevated in 167 patients (25.3%), whereas 1 year after surgery, levels were elevated in only 5 patients. Permanent diabetes insipidus occurred in 4 patients, 2 from the transsphenoidal group (0.3%) and 2 from the transcranial group (3.2%). Following transsphenoidal surgery 110 (19.6%) of patients had normal pituitary function [versus 0% after transcranial surgery], 169 (30.1%) [6 (11.3%)] showed improvement, 274 (48.9%) [49 (73.7%)] had persistent deficits and 8 (1.4%) [8 (15%)] showed deterioration of pituitary function. DISCUSSION: These data indicate that transsphenoidal surgery for non-functioning pituitary adenomas in expert hands is, relatively, far less detrimental to patients compared with transcranial surgery. The latter carries a much greater risk of post-operative deterioration in pituitary function.