Elevated serum osteopontin levels in idiopathic retroperitoneal fibrosis.

OBJECTIVES To investigate the role of serum osteopontin concentrations for monitoring idiopathic retroperitoneal fibrosis. METHODS In 22 patients with idiopathic retroperitoneal fibrosis serum concentrations of osteopontin were measured by an enzyme-linked immunosorbant assay and related to retrospectively gathered clinical data, contrast enhanced magnetic resonance imaging studies, and laboratory parameters. Patients with secondary causes, an inflammatory abdominal aortic aneurysm, and immunoglobulin G4-associated idiopathic retroperitoneal fibrosis were excluded. Twenty-two healthy volunteers served as controls. RESULTS Serum osteopontin concentrations of patients with idiopathic retroperitoneal fibrosis were elevated compared to healthy controls (p=0.017) and correlated with the transverse diameter of the periaortic cuff as determined by imaging studies (ρ=0.549; p=0.008). Patients presenting with a diameter greater than 10mm had higher osteopontin concentrations than patients with smaller diameters (p=0.004). Increased inflammatory activity as determined by the presence of contrast enhancement in imaging studies (p<0.001) and the presence of typical symptoms (p=0.013) were associated with higher osteopontin concentrations. CONCLUSIONS Serum osteopontin concentrations were elevated in patients with idiopathic retroperitoneal fibrosis. Increased concentrations correlated with the presence of clinical symptoms and extended disease or activity parameters on magnetic resonance imaging.