Leptin concentration in serum and synovial fluid of children with juvenile idiopathic arthritis

Introduction: Leptin is a polypeptide hormone synthesized mainly in adipocytes (adipose tissue). Leptin concentration in serum decreases dramatically during a low-calorie diet and weight loss. In chronic inflammation, such as juvenile idiopathic arthritis (JIA), the proinflammatory cytokines induce leptin release. The aim of the study was to assess serum and synovial fluid leptin concentration in a group of JIA and healthy children and to find out if there is a correlation between leptin serum concentration, child nutritional status and clinical state.
Material and methods: Thirty-four children with JIA and 16 healthy children as a control group were included in the study. Leptin concentration was assessed with an ELISA test. BMI and body fat percentage (BF%) in both groups of children were calculated and in JIA children disease activity was estimated.
Results: Leptin concentration in sera of JIA children was higher than in healthy children in spite of significantly lower BMI in JIA children and similar adipose tissue mass. Leptin concentration in synovial fluid was higher than in serum of JIA children. In JIA children with high disease activity leptin concentration in sera as well as in synovial fluids was higher than in children with low disease activity, but without statistical significance. There is a positive correlation between serum leptin concentration and BMI, BF%, ESR and disease duration. In the group of healthy children there is a positive correlation between serum leptin concentration and BF%.
Conclusions: The high leptin concentration in JIA children and its correlation with BMI and BF% could indicate leptin’s role in body mass regulation in the course of the chronic inflammatory process.