Effect of Sandostatin® LAR® on serum leptin levels in patients with acromegaly

Abstract

OBJECTIVE. Serum leptin levels are decreased in patients with acromegaly and rise after GH is normalized by surgical treatment. We have evaluated the effect of Sandostatin® LAR® on leptin levels in acromegalic patients since there are recent data to suggest that somatostatin, in addition to its GH lowering effect, also reduces serum leptin levels in humans. METHODS. Nineteen patients with active acromegaly were studied. Eleven patients received monthly injection of Sandostatin® LAR® and eight patients underwent transsphenoidal surgery. Serum concentrations of leptin, GH, IGF-1 and insulin were measured before and after treatment. RESULTS. Serum leptin concentrations were lower in patients with active acromegaly than controls matched for age, sex and body mass index (BMI) [2.79 μg/l (2.60) vs. 4.41 μg/l (5.07); median (interquartile range); P< 0.01]. A positive correlation between serum leptin concentrations and BMI was observed in the controls (r = 0.46, P < 0.05) but not in the acromegalic patients before treatment (r = 0.32, ns). In the group of patients treated with Sandostatin® LAR®, a marked reduction in GH and IGF-1 was achieved by week 8 and GH and IGF-1 remained suppressed throughout the 6 months of treatment. There was no change in BMI. A significant increase in leptin levels only became evident after 6 months of treatment [2.99 μg/l (2.60) vs. 4.21 μg/l (3.84), P< 0.05]. Leptin levels also significantly increased after transsphenoidal surgery [3.05 μg/l (5.73) vs. 5.19 μg/l (4.93), P< 0.05]. The positive correlation between serum leptin concentrations and BMI was restored in acromegalic patients both after treatment with Sandostatin® LAR® (r= 0.62, P < 0.05) and after surgery (r = 0.81, P < 0.05). CONCLUSION. Leptin concentrations were decreased in patients with active acromegaly and lowering GH by either Sandostatin® LAR® or transsphenoidal surgery led to an increase in leptin concentrations.