Serum high-sensitivity C-reactive protein is not increased in patients with IgA nephropathy

Background/aims: The development of renal injury in glomerulonephritis (GN) has been related to systemic inflammatory mediators. We investigated whether serum high-sensitivity C-reactive protein (hs-CRP) is a marker reflecting the inflammatory pathogenesis of primary GN.

Methods: We compared serum hs-CRP levels in 192 patients with IgA nephropathy (IgAN), 43 patients with membranous nephropathy (MN), and 25 patients with minimal change disease (MCD) undergoing kidney biopsy and 638 matched controls.

Results: There were no differences in hs-CRP levels between controls (median 0.08 mg/dl; range 0.03-1.87 mg/dl) and patients with IgAN (0.08 mg/dl; 0.03-3.13 mg/dl), MN (0.07 mg/dl; 0.03-0.99 mg/dl) or MCD (0.08 mg/dl; 0.03-1.75 mg/dl). In patients with IgAN, hs-CRP levels did not differ according to Haas' pathological subclasses or subsequent renal outcomes. In the IgAN group, hs-CRP showed positive correlations with IgA, uric acid, systolic blood pressure, BMI and age. Hs-CRP level was significantly higher in male than in female IgAN patients. Serum IgA concentration was the strongest independent correlate with hs-CRP levels, and gender and BMI were also independently associated with hs-CRP. There were no correlations between hs-CRP and markers of disease activity.

Conclusion: It is likely that hs-CRP does not closely reflect inflammatory pathogenesis in patients with IgAN, MN and MCD.