IgA nephropathy in a patient with inflammatory bowel disease

Excerpt

A 41-year-old diagnosed with Crohn's colitis (A2L2B1 disease) presented with elevated blood pressure and a purpuric rash (Fig. 1) over 10 days while on infliximab and azathioprine. Despite normal renal function, urine analysis showed significant proteinuria (302 mg/L) and hematuria. A kidney biopsy revealed sclerosed glomeruli, tubular atrophy with interstitial fibrosis and increased mesangial matrix (Fig. 2). Immunohistochemistry confirmed immunoglobulin A (IgA) positivity, C3, kappa and lambda, indicating IgA nephropathy. Infliximab levels were < 0.8 mg/L and anti-infliximab antibodies were 400 AU/mL (enzyme-linked immunosorbent assay [ELISA], ≥ 10 is positive).

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