Objective: In active acromegaly body composition is characteristically altered by an increase in lean body mass and a corresponding reduction in fat mass. These changes are induced by an excessive secretion of GH and insulin-like growth factor I (IGF-I). Growth hormone is an anabolic hormone and leads to stimulation of protein synthesis and an increased lipolysis in adipose tissue. Treatment with the somatostatin analogue, octreotide, has been shown to reduce GH levels causing reduced hormonal effects on target tissues. We have studied changes in body composition during short-term reduction in GH level by octreotide in active acromegaly.
Design: Octreotide was compared to placebo in a double-blind, cross-over trial. Dual-energy X-ray absorptiometry scanning was employed to calculate body composition. Relations between body composition parameters and clinical signs of acromegaly (finger circumference and foot volume) were studied.
Patients: Twelve patients with active acromegaly, confirmed by lack of GH suppression during oral glucose loading, were included. All had pituitary adenomas diagnosed by computed tomography.
Measurements: Serum GH and IGF-I. Lean body mass, fat mass and total weight, foot volume and finger circumference.
Results: Four weeks of octreotide treatment caused a 75% decrease in GH levels (n = 10), a reduction in IGF-I from 476 +/- 51.9 (mean +/- SEM) to 233 micrograms/l +/- 46.3 (P < 0.005) and a corresponding decrease in both body weight (2.51 kg +/- 0.41) (P < 0.005) and lean body mass (2.44 kg +/- 0.48) (P < 0.005). No significant changes in fat mass were observed. These findings were paralleled by significant reductions in foot volume (44.50 ml +/- 17) (P < 0.05) and finger circumference (1.3 mm +/- 0.3) (P < 0.05).
Conclusions: Short-term octreotide therapy reduces growth hormone levels leading to a significant reduction in lean body mass as assessed by dual-energy X-ray absorptiometry. Alterations in lean body mass were positively correlated with reductions in foot volume. Thus, simple clinical tests may be valuable in judging the effects of treatment in active acromegaly.