Serum and synovial fluid insulin like growth factor-1 and its binding protein-3 in rheumatoid arthritis

ABSTRACT

Insulin-like growth factor-1 [IGF-1] and its binding protein-3 [IGFBP-3] in human synovial fluid play an important role in maintaining articular cartilage metabolism. In this study, we measured serum and synovial fluid [SF] concentrations of IGF-1 and IGFBP-3 in 20 rheumatoid arthritis patients [RA] and 10 matched controls [with traumatic knee effusion] using radioimmunoassay. Also, we tried to correlate serum and synovial levels with each other and with disease activity and severity measures. Our results showed a significant increase in synovial fluid level of both IGF-1 and IGFBP-3 in RA patients as compared to controls. Serum IGF-1 correlated with synovial fluid level but serum IGFBP-3 did not correlate with synovial fluid level. Disease activity markers correlated significantly with synovial fluid IGF-12 and IGFBP-3 levels, but did not show significant correlation with their serum level. In conclusion the pattern of IGF-1 and IGFBP-3 in SF differs in inflammatory versus non-inflammatory joints