Relationship between growth hormone–IGF-I–IGFBP-3 axis and serum leptin levels with bone mass and body composition in patients with rheumatoid arthritis

Objectives. Hormonal factors playing a role in bone mass and body composition have been rarely assessed in rheumatoid arthritis (RA). In this study, we aimed to evaluate the growth hormone (GH)-insulin-like growth factor-I (IGF-I)-insulin-like growth factor binding protein-3 (IGFPB-3) axis and serum leptin levels in patients with RA and to determine whether these hormonal/growth factors may influence bone mass and body composition in RA. Methods. Serum GH, IGF-I, IGFPB-3 and leptin were evaluated in 38 corticosteroid-treated RA patients, 14 non-RA patients under corticosteroids (corticosteroid controls, CC) and 32 healthy controls (HC). Bone density was evaluated using dual X-ray absorptiometry (DEXA), and expressed as bone mineral density (BMD), and quantitative ultrasound (QUS). Body composition was assessed by DEXA. Results. The three groups differed regarding femoral neck, total body BMD, lean mass and QUS parameters with lower values in the RA group (all P ≤ 0.05). Growth hormone was higher in RA patients (P = 0.0001) while IGF-I and IGFBP-3 did not differ between the three groups. In RA patients there was a tendency to high serum leptin levels and leptin strongly correlated with fat mass (r = 0.83, P < 0.0001), but not with bone mass measurements or inflammatory parameters. There were no differences for lean mass, GH and leptin between CC and HC. Conclusion. Our results suggest that these GH and leptin modifications could have an influence on both bone mass and body composition in RA.