From the Guidelines
Patients with Crohn's disease are at risk of developing chronic kidney disease (CKD) primarily through mechanisms involving chronic inflammation, nephrolithiasis, hydronephrosis, medication-induced nephrotoxicity, and complications arising from malnutrition and dehydration. The pathogenesis of CKD in Crohn's disease is multifactorial, involving:
- Chronic inflammation leading to amyloidosis, where inflammatory proteins deposit in kidney tissues, impairing function 1
- Nephrolithiasis (kidney stones) due to increased oxalate absorption from intestinal malabsorption, particularly after ileal resection
- Hydronephrosis resulting from intestinal inflammation causing ureteral obstruction
- Medication-induced nephrotoxicity, with 5-aminosalicylates potentially causing interstitial nephritis, and cyclosporine and tacrolimus causing direct renal damage
- Dehydration from chronic diarrhea leading to prerenal azotemia
- Malnutrition and vitamin D deficiency contributing to kidney damage over time
- Recurrent urinary tract infections due to fistula formation between the intestine and urinary tract damaging the kidneys
Key factors to consider in the management of Crohn's disease to prevent or mitigate CKD include:
- Regular kidney function monitoring, especially in patients on potentially nephrotoxic medications
- Adequate hydration
- Prompt treatment of complications
- Nutritional support to prevent malnutrition, which is common in Crohn's disease and can exacerbate kidney damage, as highlighted in recent guidelines on clinical nutrition in inflammatory bowel disease 1
From the Research
Mechanism of CKD in Crohn's Disease
- Chronic inflammation in Crohn's disease can lead to secondary amyloidosis, a rare but serious complication that can cause kidney damage and impair renal function 2, 3.
- The deposition of amyloid proteins in the kidneys can disrupt normal kidney architecture and function, leading to nephrotic syndrome, impaired renal function, and eventually renal failure 3, 4.
- The incidence of secondary amyloidosis in patients with Crohn's disease has been reported to be 0.5%-8%, with renal failure being the most common clinical presentation 3.
- Studies have shown that controlling inflammation in Crohn's disease can help prevent or partially reverse the progression of renal AA-amyloidosis, and that immunosuppressive drugs and anti-TNF-α agents may be effective in treating this condition 4, 5.
- Kidney transplantation may be a viable option for patients with Crohn's disease who develop end-stage renal failure due to amyloidosis, with excellent patient and graft survival rates reported in some studies 5, 6.
Key Factors Contributing to CKD in Crohn's Disease
- Persistent systemic inflammation 2, 3
- Deposition of amyloid proteins in the kidneys 3, 4
- Nephrotic syndrome and impaired renal function 3, 5
- Uncontrolled Crohn's disease activity 4, 5
- Genetic predisposition (not explicitly mentioned in the provided studies, but potentially relevant)