Renal Involvement in Adult Patients With Inflammatory Bowel Disease and Its Relation to Duration and Disease Activity

Inflammatory bowel disease (IBD), comprising ulcerative colitis (UC) and Crohn's disease (CD), is a chronic immunemediated disorder of the gastro-intestinal tract characterized by recurrent inflammation and epithelial injury of the intestine. Extraintestinal manifestations are seen in 6% to 47% of patients diagnosed with IBD. Renal and urinary tract involvement occurs in 4% to 23% of patients with IBD, with renal calculi being the most common form of renal involvement. IBD is associated with a range of renal manifestations, including nephrolithiasis, glomerulonephritis, tubulointerstitial nephritis, and secondary amyloidosis, which can lead to acute or chronic renal insufficiency. Several potential mechanisms might contribute to the higher risk of incident CKD and AKI in patients with IBD. First, in the context of IBD, acute or chronic loss of circulating volume (salt and water depletion) due to persistent inflammation of the intestine and repeated intestinal resection could lead to electrolyte abnormalities followed by acute and chronic loss of kidney function, which may not be always reversible. Second, dysbiosis in patients with IBD is associated with increased production of microbiota-derived uremic toxins and microinflammation, both of which promote the progression of renal diseases. Third, IBD-related alterations in the innate and adaptive immune systems may lead to elevated proinflammatory cytokines, which are particularly implicated in the progression of renal disease. Understanding these associations is crucial for management and monitoring of IBD patients, particularly for those who may develop renal complications, so mitigating impact on kidney function and overall health.