Nephrolithiasis in Crohn’s Disease Patients: A Review of the Literature Original paper

What was studied?

This review article examines the relationship between nephrolithiasis (kidney stones) and Crohn’s disease, a common form of inflammatory bowel disease (IBD). It focuses on the risk factors, pathophysiology, and management of nephrolithiasis in Crohn’s disease patients. The study also discusses preventative strategies for reducing kidney stone formation in these patients. It is well established that patients with Crohn’s disease are at an increased risk for nephrolithiasis, and this review highlights the complex mechanisms, including altered gut flora, intestinal inflammation, and dietary habits, which contribute to stone formation in IBD. The article further investigates the role of dehydration, high protein diets, and bowel resections as significant contributors to kidney stone formation in Crohn’s disease patients.

Who was studied?

The review draws from various studies focusing on patients with Crohn’s disease who have developed nephrolithiasis. This includes both adult and pediatric populations, with a particular focus on individuals who have undergone abdominal surgeries such as bowel resection or ileostomies, which are commonly performed in Crohn’s disease management. The article also incorporates data from large cohort studies and case series that provide a comprehensive view of the prevalence and risk factors associated with kidney stones in this patient group. Patients who have had surgery for Crohn’s disease are considered to be at higher risk for nephrolithiasis, particularly those who develop steatorrhea and malabsorption as a result of small bowel resections.

Most important findings

The review reveals that the incidence of nephrolithiasis in Crohn’s disease patients ranges from 7% to 28%, significantly higher than the general population’s lifetime risk of 1-15%. The most common type of kidney stones in Crohn’s patients are calcium oxalate stones, which are often linked to increased urinary oxalate excretion and reduced levels of calcium and magnesium in the urine. The pathophysiology of nephrolithiasis in Crohn’s disease is multifactorial. Chronic diarrhea, malabsorption, and dehydration are major contributors to increased urinary oxalate levels, while small bowel resections can lead to fat malabsorption, which subsequently enhances oxalate absorption. Furthermore, Crohn’s disease patients are often at risk for altered intestinal microbiota, leading to reduced levels of oxalate-degrading bacteria, which further increases the risk of oxalate stone formation.

Additionally, the review emphasizes the role of diet in kidney stone formation. Patients with Crohn’s disease tend to have a high-protein, high-oxalate diet, which contributes to elevated urinary oxalate excretion. The reduction in urinary citrate due to small bowel disease or resections also promotes stone formation, as citrate is an inhibitor of calcium oxalate crystallization. Uric acid stones also occur in Crohn’s patients, particularly those with ileostomies, as they experience increased urine acidity due to bicarbonate losses. This combination of risk factors—dehydration, high dietary protein, and altered intestinal absorption—results in a higher incidence of nephrolithiasis in Crohn’s disease patients.

Key implications

The review stresses the importance of preventive measures to reduce the risk of nephrolithiasis in Crohn’s disease patients. Given the high prevalence of kidney stones in this population, clinicians should consider strategies such as increased fluid intake to produce at least 2.5 liters of urine per day, dietary modifications to reduce sodium and animal protein intake, and increasing the consumption of fruits and vegetables to improve citrate levels and reduce urinary supersaturation. For patients with a history of bowel resections or ileostomies, careful monitoring of kidney function and urine composition is crucial. Additionally, the review highlights the importance of early diagnosis and prompt treatment of nephrolithiasis to prevent complications like chronic kidney disease (CKD) or end-stage renal disease (ESRD). This includes the use of imaging techniques, such as ultrasound or CT scans, to detect kidney stones early in symptomatic patients.