What is the reason behind renal calculi in massive small bowel resection?

Any disease, traumatic injury, vascular accident, or other pathology that leaves less than 200 cm of ble small bowel or results in a loss of 50% or more of the small intestine places the patient at risk for developing sho-bowel syndrome. Sho-bowel syndrome is a disorder clinically defined by malabsorption, diarrhea, steatorrhea, fluid and electrolyte disturbances, and malnutrition. The oxalate is normally bound by calcium in the small bowel and thus is insoluble when it reaches the colon. After massive enterectomy, much of this calcium is bound by free intraluminal fats. Free oxalate is delivered to the colon, where it is absorbed. This can eventually lead to saturation of the urine with calcium oxalate crystals and result in stone formation. The most common causes of sho-bowel syndrome in adults include Crohn disease, radiation enteritis, mesenteric vascular accidents, trauma, and recurrent intestinal obstruction. In the pediatric population, necrotizing enterocolitis, intestinal atresias, and intestinal volvulus are the most common etiologic factors.