Effects of GH-IGF-I excess and gonadal status on bone mineral density and body composition in patients with acromegaly.

SUMMARY: Studies on body composition and bone mineral density in acromegaly have conflicting results. Our data point to an increase in lean mass, a decrease in adipose tissue, and that the anabolic effect of GH on bone is partially dependent on modifications in body composition.
INTRODUCTION: The effects of growth hormone (GH) and insulin-like growth factor I (IGF-I) excess and gonadal status on bone mineral density (BMD) and body composition (BC) in acromegalic patients are uncertain.
METHODS: Bone mineral density and BC were evaluated by dual-energy X-ray absorptiometry (Prodigy-GE) in 75 patients (22 men and 53 women) with acromegaly, mean age 48.9 ± 14.5 years. Acromegaly was considered "controlled" when serum IGF-I was within the specific age-adjusted reference range, and serum GH was lower than 2.5 ng/mL. Comparisons between groups were performed using unpaired t test or Mann-Whitney U test. Categorical variables were analyzed by chi-square (x (2)) test. In order to compare data of different subgroups stratified by disease activity and gonadal status, one-way analysis of variance (ANOVA) and Bonferroni post hoc analysis were performed. To evaluate the correlation between GH and IGF-I and densitometric parameters, Pearson and Spearman rank order correlation were performed, as appropriate.
RESULTS: There were no differences in BMD when considering disease activity and gonadal status. Active disease and eugonadism were positively correlated to an increase in lean mass and a decrease in fat mass. After multiple linear regression, there were positive correlations between GH and Z-score at lumbar spine and between lean mass and BMD at proximal femur.
CONCLUSION: Our data support that GH-IGF-I excess and eugonadism have great influence on BC modifications and that the anabolic effects of GH-IGF-I on bone are, at least in part, dependent on these alterations in body composition.