Failure of selective pituitary adenomectomy to cure acromegaly

Complete selective pituitary adenomectomy for acromegaly may fail to cure the underlying endocrinopathy. A 40-year-old man who had acromegaly of ten-years duration was initially treated with pituitary irradiation eight years prior to surgery. Three years after irradiation his mean GH concentration decreased from 53 to 9.0 ng/ml, then subsequently increased, and was associated with development of severe hyperglycemia. A transsphenoidal microdissection was performed, and a discrete pituitary adenoma was visualized and totally removed at surgery. GH concentrations decreased from 46 to 5.0 ng/ml one week after surgery and to 3.0 ng/ml 10 months after surgery. Despite improvement postoperatively, the patient still demonstrated abnormal GH dynamics and responses to the GTT, abnormal nocturnal and random GH sampling, and abnormal responses to the L-dopa, apomorphine, and TRH stimulation tests. Acromegaly could be caused by either hypothalamic hyperfunction, an autonomous pituitary tumor, or both; but the latter would not explain the results obtained in this patient. This suggests that reduction of GH to normal concentrations following selective pituitary adenomectomy is not synonomous with curing acromegaly.