Urinary Nephrin and Alpha One Microglobulin as Early Renal Injury Biomarkers in Patients With Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory condition of the gastrointestinal tract. Crohn's disease and ulcerative colitis are the two principal types of IBD. The prevalence of IBD has been increasing worldwide . Extraintestinal manifestations of IBD are common, occurring in 6% to 47% of patients involving nearly every organ system .

Renal and urinary system involvement are common in IBD patients with incidence varying from 4% to 23% and is greater in patients with more severe and long-standing disease. Apart from secondary complications, such as nephrolithiasis, hydronephrosis and amyloidosis, other disorders have also been reported. Membranous glomerulonephritis, rapidly progressive glomerulonephritis, mesangiocapillary glomerulonephritis, IgA nephropathy, thin basement membrane disease and kidney granuloma found to be connected with IBD. In addition, non-specific morphological changes in the glomeruli of patients with IBD, like podocyte effacement and mesangial deposition of immunoglobulin and complement have been well documented. Cases of interstitial nephritis reported to be attributed to the nephrotoxic effect of aminosalicylates which used in IBD treatment.

Alpha one microglobulin is a relatively small protein that undergoes glomerular filtration followed by reabsorption and catabolism in the proximal tubules. Increased urinary α1-microglobulin concentration therefore provides an index of proximal tubule dysfunction .

Glomerular filtration barrier related protein changes have not been closely investigated in IBD patients . Nephrin is podocyte-associated protein that play key roles in maintaining the structural and functional integrity of the kidney's filtration barrier. The shedding of nephrin reflects compromisation of podocytes' functional and structural integrity.