Can immediate postoperative random growth hormone levels predict long-term cure in patients with acromegaly?

Growth hormone (GH) levels following oral glucose tolerance test (OGTT) at 12 weeks or later after surgery have been accepted as the most reliable parameter for defining remission and/or cure in patients with acromegaly. However, the role of random GH in predicting remission in the immediate postoperative period using modern criteria is not known. This study was undertaken to evaluate the role of random GH levels in first 5 postoperative days as an early predictive tool for long-term remission of patients with acromegaly following transsphenoidal pituitary surgery (TSS).

Seventy-five consecutive acromegaly patients with at least three postoperative OGTT values at 3, 6, and 12 months of follow-up were included in the study. GH levels were measured just before surgery, in the immediate postoperative period, at 6 h and on day 1 to day 5 after surgery. Remission was defined as normal age-specific insulin-like growth factor-1 and either basal fasting GH <1 ng/ml or a nadir GH following OGTT <0 .4 ng/ml at 3 months of surgery.

Of the 75 patients with acromegaly who underwent TSS, long-term remission was achieved in 42 (56%) patients. GH values ≤1.55 ng/ml at 6 h of surgery showed the highest predictive power for long-term remission, with a sensitivity of 81.2% and a specificity of 83.3%. The duration of disease and tumor volume had no effect on the 6 h GH value-related prediction of cure.

Early postoperative GH values may be used to predict long-term cure. A value of ≤1.5 ng/ml at 6 h following surgery may predict long-term cure in two-thirds of the patients with acromegaly who undergo TSS.