Osteocalcin, OPG and RANKL circulating levels in adolescent idiopathic scoliosis
Oana Popa1, Mariana Chiru Anton2, Susana Vladoiu1, Dana Manda1 & Olga Ianas1
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.