Delayed Remission of Growth Hormone-Secreting Pituitary Adenoma After Transsphenoidal Adenectomy

OBJECTIVE: To investigate the clinical characteristics of delayed remission (DR) of growth hormone (GH)-secreting pituitary adenoma after transsphenoidal adenectomy and inform follow-up treatments. METHODS: We retrospectively reviewed 87 patients who had undergone transsphenoidal surgery for acromegaly. Demographic, radiological, and endocrinological data were reviewed before, immediately after, 3 months after, and in the long term (2.4 +/- 1.1 years) after surgery. The definition of DR was that patients did not achieve GH remission immediately, 3 months, or later after surgery, but did so in the long term without any additional postoperative treatment. RESULTS: Fifty-one patients (58.6%) achieved long-term GH remission. There were 24 (27.6%) DR patients immediately postoperatively and 9 (10.3%) DR patients 3 months postoperatively. On average, the 24 DR patients achieved remission at 10.2 (range, 3-32) months. Immediate postoperative random and nadir GH after an oral glucose load were significantly lower in the DR group than in the non-remission group (2.73 +/- 3.17 and 2.03 +/- 2.59 vs. 8.05 +/- 10.35 and 5.55 +/- 5.91 mu g/L, respectively). Three-month postoperative nadir GH was significantly lower in the DR group than in the nonremission group (1.63 +/- 2.82 vs. 3.48 +/- 4.25 mu g/L, P = 0.007). Immediate postoperative random GH effectively predicted long-term remission (Spearman's rho = 0.513, area under the curve = 0.905 > 0.90). However, the best predictor of long-term remission was 3-month postoperative nadir GH (Spearman's rho = 0.728, area under the curve = 0.944 > 0.90), with 76.5% sensitivity and 97.2% specificity. CONCLUSIONS: For certain groups of patients likely to achieve DR, additional treatments should not be performed early after surgery. Prolonged follow-up and close observation could help determine the therapeutic effect of surgery and guide postoperative treatments.