Endocrine Abstracts

Introduction: Growth hormone (GH) level is a direct marker of active residual adenoma tissue after acromegaly surgery. However, the value of early postoperative GH for prediction of surgical cure in acromegaly has not been established and therefore is not used in everyday clinical practice.

Aim: The aim of our work was to study the 24-hour basal postoperative GH level and the nadir of GH level after the oral glucose tolerance test (OGTT) two weeks after surgery as predictors of surgical cure in acromegaly.

Materials and methods: A prospective cohort study included patients with newly diagnosed acromegaly. All patients underwent transsphenoidal surgery (TSS) performed by one neurosurgeon. The basal GH level 24 hours after surgery and the nadir GH in OGTT carried out two-weeks postoperatively were measured in all cases. The results of TSS were estimated twelve months after operation. The biochemical remission of acromegaly was defined as nadir GH level in on an OGTT < 0.4 µg/l along with age and gender normalized values of insulin-like growth factor 1 (IGF-1).

Results: Thirty-nine patients (32 women and 7 men) with mean age 53.0 ± 7.9 years (35–63 years) were enrolled into the study. 31 patients harbored macroadenomas (79.4%). Remission rate was 46.1% (18/39) on follow-up after 12 months (in microadenomas it was 75% (6/8), in macroadenomas – 38.7% (12/31)). Preoperative basal GH and IGF-1 levels did not differ in remission and persistence groups. Basal 24-hour postop GH level decreased in all patients when compared with baseline and was significantly lower among patients in remission group: 1.8 ± 0.9 vs 5.3 ± 2.8 µg/l, P = 0.0002. The GH level <1.30 µg/l showed the highest prognostic value for acromegaly remission with sensitivity of 93.7% (95% CI, 81.1–98.3) and specificity of 83.5% (95% CI, 60.1–93.8). The nadir GH level <1.0 µg/l in two-week postop OGTT had a sensitivity of 85.7% (95% CI, 60.1–97.5) and specificity of 80.0% (95% CI, 54.8–92.9) in prediction of acromegaly remission 12 monthsafter surgery.

Conclusion: Early postoperative GH level can predict the outcome of surgical treatment in acromegaly. Our data suggests that the basal 24-hours postoperative GH < 1.3 µg/is a stronger predictor of acromegaly remission after TSS than the nadir GH < 1.0 µg/l in two-week postop. These findings require further research.