Abstract
The clinical significance of abnormal growth hormone (GH) secretion in response to thyrotropinreleasing hormone (TRH) and luteinizing hormone-releasing hormone (LHRH) was studied in 52 patients with acromegaly due to GH secreting pituitary adenomas treated by trans-sphenoidal microsurgery. The mean period of postoperative follow-up was 4.1 years. In 27 of the 36 patients who had abnormal GH responses to TRH or LHRH before surgery, basal GH levels normalized and abnormal GH responses disappeared immediately after surgery. Among the remaining nine patients, four had normal basal GH levels with abnormal GH responses and five showed persistently abnormal basal GH levels as well as abnormal GH responses. Recurrence requiring retreatment was not observed during follow-up in any of the 31 patients with normal postoperative basal GH levels, regardless of the GH response to TRH or LHRH. All five patients with abnormal basal GH and abnormal GH responses required additional treatment.
Among the patients who underwent long-term postoperative TRH and LHRH testing, abnormal GH responses reappeared in three of 19 whose abnormal responses had disappeared immediately after surgery. The abnormal response disappeared spontaneously in two of three patients who had abnormal responses immediately after surgery. In four patients with both abnormal GH responses and abnormal basal GH levels immediately after surgery, abnormal GH responses persisted throughout the follow-up period. In addition, the abnormal GH responses appeared in two of 14 patients who had been nonresponsive before surgery.
These results indicate that the postoperative GH response to TRH or to LHRH was not significantly related to the outcome. Therefore, additional or prophylactic treatment should not be administered solely on the basis of the persistence of abnormal GH response. The most reliable predictor of longterm outcome appears to be the basal GH level immediately after surgery.
