Spectrum and prognosis of renal histopathological lesions in patients with inflammatory bowel disease: a cross-sectional study from a single center in China.

To explore the spectrum, clinicopathological features and prognosis of patients with inflammatory bowel disease (IBD) including Crohn's disease (CD) and ulcerative colitis (UC) with renal involvement. Included in this cross-sectional study were 36 IBD patients, in whom renal biopsy was performed to analyze the histological pattern and prognosis. Renal histopathology was examined by light microscopy and immunofluorescence using the standard procedures. Renal function decline was defined as a twofold increase in serum creatinine (SCr) after biopsy, initiation of dialysis and transplantation. Of the 36 IBD patients (22 UC and 14 CD), renal biopsy was performed in 33 cases. Compared with UC patients, CD patients were significantly younger at presentation and had a higher proportion of chronic renal insufficiency (CRI). The most common renal histological pattern in the 33 biopsy cases was IgA nephropathy (66.6%), followed by membrane nephropathy (9.1%), amyloidosis (9.1%), tubulointerstitial nephritis (9.1%), and membranoproliferative glomerulonephritis (6.1%). Renal function decline occurred in 4 patients (1 with amyloidosis, 1 with TIN and 2 with CRI). Factors associated with renal function decline included CD and a higher SCr level at presentation. Urinalysis and renal function test should be routinely examined in IBD patients. Renal biopsy can provide useful information about the histological patterns and therefore should be considered in IBD patients with renal lesions.