Synovial and serum levels of osteocalcin, osteoprotegerin and β-crosslaps in patients with calcium pyrophosphate deposition disease

Background. Calcium pyrophosphate deposition disease is defined by deposition of calcium pyrophosphate crystals in hyaline cartilage, fibrocartilage and soft tissues. The study of bone markers is of great interest in different types of arthritis. In patients with calcium pyrophosphate deposition disease, bone turnover markers may yield additional information from many perspectives. Objectives. To measure synovial and serum levels of osteocalcin, osteoprotegerin and β-CrossLaps in patients with calcium pyrophosphate deposition disease. Material and methods. In this pilot, prospective study were enrolled eight patients with calcium pyrophosphate deposition disease. Osteocalcin, osteoprotegerin and β-CrossLaps were measured in serum and in the synovial fluid using ELISA kits. Results. Synovial fluid osteocalcin was significantly lower comparative with serum osteocalcin (2.1±0.6 versus 9.21 ±46, p=0.02). Synovial fluid osteoprotegerin was significantly higher than serum osteoprotegerin (55.5±284 versus 8.44±7; p=0.0001). Synovial fluid β-CrossLaps wasn’t statistically different from serum levels (6146±66818 versus 6077±12212; p=0.5). Ratios between synovial fluid and serum levels were 0.22 for osteocalcin, 6.57 for osteoprotegerin and 1.01 for β-CrossLaps. Conclusions. Osteocalcin was higher in serum than in the synovial fluid. β-CrossLaps had similar values in serum and synovial fluid. Osteoprotegerin was higher in synovial fluid than serum.