To study insulin-like factor-I (IGF-I) levels in children and adolescents with connective tissue diseases (CTDs), compare them with values obtained in normal controls, and correlate them with age, sex, steroid treatment, and inflammatory parameters.
A multicenter, cross-sectional study was performed in 3 Italian pediatric rheumatology centers. The subjects studied comprised 117 patients with juvenile arthritis (53 systemic, 25 pauciarticular and 17 polyarticular) and other CTDs (22), and 78 children without inflammatory conditions. IGF-I levels were measured by radioimmunoassay after acid-ethanol extraction.
Mean IGF-I serum levels were 167.6 ng/ml (+/- 132.5) in patients and 214.4 (+/- 142.8) in controls. A significant correlation was found between IGF-I levels and age in the controls (P = 0.001), but not in the patients. Covariance analysis with age as the covariate showed significantly lower IGF-I levels in the patient group (P = 0.001). No significant correlation was found between IGF-I levels and the total quantity of steroid taken. Multiple regression analysis showed that IGF-I levels were inversely correlated with the ESR (P = 0.0001) and positively correlated with age (P = 0.0002) and sex (P = 0.021) in the patient group.
IGF-I serum levels are decreased in patients with CTDs; inflammation could play a major role.