Background. Inflammation is implicated in cardiovascular disease (CVD) and mortality in end-stage renal failure (ESRF). Its importance in early renal disease is yet to be defined.Methods. Serum levels of systemic and vascular inflammatory markers in early IgA nephropathy (IgAN) and control subjects were measured and related to renal function and vascular risk factors. A parallel study in type 1 diabetes mellitus subjects with (T1DM Nx) and without nephropathy (T1DM No Nx) was performed.Results. Fifty-one IgAN patients aged 46±2 years (mean±SEM), calculated creatinine clearance (CrCl) 88±5 ml/min, were compared with 51 matched control subjects. Forty-six T1DM Nx patients aged 40±2 years, CrCl 84±5 ml/min, and 73 T1DM No Nx patients aged 38±2 years were also compared. High sensitivity C-reactive protein (hsCRP) was elevated in IgAN, T1DM Nx and T1DM No Nx patients compared with controls [4.2±0.6 (P<0.001), 4.1±0.6 (P<0.001), 2.6±0.4 (P<0.05) vs 1.6±0.3 mg/l]. Levels in T1DM Nx patients were higher than in T1DM No Nx patients (P<0.05). Inflammation and vascular dysfunction as measured by pulse pressure (PP) were related. HsCRP correlated with PP in IgAN and T1DM Nx (r = 0.47, P = 0.001; r = 0.40, P<0.05). PP was the strongest independent predictor of hsCRP in IgAN (T = 2.45, P<0.001), while body mass index (T = 7.83, P<0.001) was the strongest predictor in T1DM Nx. Endothelial cell adhesion molecules were increased in T1DM Nx>IgAN>T1DM No Nx vs controls: soluble vascular adhesion molecule-1 (sVCAM-1) 760±30 (P<0.001)>663±34 (P = 0.001)>601±21 (P<0.05) vs 536±15 ng/ml; soluble intracellular adhesion molecule-1 (sICAM-1) 320±8 (P<0.001)>313±13 (P<0.001)>307±8 (P<0.001) vs 244±6 ng/ml. sVCAM-1 levels were higher in T1DM Nx than in T1DM No Nx, P<0.001. In IgAN and T1DM Nx, hsCRP correlated with sICAM-1 (r = 0.33, P = 0.017; r = 0.37; P = 0.017). sVCAM-1 was related to renal function in IgAN and T1DM Nx: serum cystatin C (r = 0.63, P<0.001: r = 0.425, P = 0.002), and urine protein:creatinine ratio in IgAN (r = 0.48; P = 0.001).Conclusions. Systemic and vascular markers of inflammation are increased in early renal disease and relate to renal dysfunction and cardiovascular risk factors. Inflammation may be a common process in various renal diseases and may link and accelerate renal dysfunction and CVD. [ABSTRACT FROM AUTHOR]