The Preoperative Paradoxical GH Response to Oral Glucose Load Predicts a low Risk of Recurrence in Acromegaly.

Context: a paradoxical growth hormone (GH) response to oral glucose load (OGTT) in acromegaly is associated with a milder phenotype.

Objective: To study whether the GH response to OGTT predicts the risk of recurrence after initial surgical cure.

Design: Retrospective, observational study.

Setting: Two tertiary care centers.

Patients: We investigated 254 patients with acromegaly who were cured by surgery.

Intervention: All patients underwent OGTT at diagnosis before pituitary surgery. A peak-to-basal GH ratio ≥ 120% within 90 minutes was used to distinguish paradoxical (GH-Par) from non-paradoxical acromegalic patients (GH-NPar).

Main Outcome Measure: Cox analysis was used to investigate whether the paradoxical GH response to OGTT was associated with the risk of disease recurrence.

Results: A paradoxical GH response to OGTT occurred in 87 patients (34.3%, termed GH-Par group). Recurrence of acromegaly occurred in three patients of the GH-Par group (3.4%) and in 20 patients in the GH-NPar group (12.0%). In the multivariate analysis, the paradoxical GH response to OGTT was significantly associated with the risk of recurrence (HR 0.18, 95% CI, 0.05-0.63; P = 0.007). Basal GH level at diagnosis was the only other variable associated with the risk of disease recurrence (HR 1.58, 95% CI, 1.01-2.47; P = 0.04).

Conclusions: our study demonstrates that a paradoxical GH response to OGTT in the preoperative setting predicts a lower risk of disease recurrence after initial surgical cure. The pattern of GH responsiveness to OGTT is, therefore, useful to predict the long-term outcome of patients with acromegaly.