Endocrine Abstracts

Background: Idiopathic scoliosis is a pathological entity of unknown etiology, characterized by a three-dimensional deformity of the spine and a low bone mass. The exact mechanism of bone loss in idiopathic scoliosis is unknown yet. However is well known that RANKL is a potent stimulator of bone resorption by binding receptor activator of nuclear factor-kB (RANK) in the osteoclasts cell membrane. OPG is a decoy receptor for RANKL, which interferes with RANKL/RANK binding and inhibits the maturation and activation of osteoclasts.

Objective: Evaluation of osteocalcin, OPG and RANKL circulating levels and of RANKL/RANK and OPG balance in adolescent with idiopathic scoliosis comparing with normal subjects at the same age.

Materials and methods: Fifteen adolescents – four boys and 11 girls – with idiopathic scoliosis and eight healthy adolescents – two boys and six girls – were enrolled. The study had the Ethical Committee approval. Radiological, biochemical, haematological and hormonal evaluations were made. Blood samples were collected every 4 h during day and 2 h during night for 24 h period. Serum levels of osteocalcin, OPG and RANKL were measured.

Results: Significantly higher levels of osteocalcin (P<0.01) and RANKL (P<0.01) were observed in adolescents with idiopathic scoliosis compared with control group. OPG showed no differences between the too groups of study. RANKL/OPG ratio was significantly higher (P<0.01) compared with control group.

Conclusion: Higher levels of RANKL in the presence of increased levels of osteocalcin may induce bone-remodelling changes due to an imbalance in RANK/RANKL/OPG system.