Urinary oxalate excretion related to ileocolic surgery in patients with Crohn's disease

Urinary oxalate excretion was studied in healthy subjects and before and after surgery in patients with Crohn's disease. Urinary oxalate excretion in relation to the length of diseased or resected ileal segment in patients subjected to restorative and colectomy procedures, as well as in relation to faecal excretion of fat and bile salts and to urinary excretion of vitamin B12 and calcium, was also studied. The studies were performed in patients on a free diet or standard hospital diet and on a high-oxalate and/or high-fat diet. When patients subjected to ileal resection in conjunction with minor colonic resection were studied on a high-oxalate diet, urinary oxalate excretion increased with length of ileum resected and correlated with faecal fat excretion and urinary excretion of vitamin B12 but not with faecal excretion of bile salts. Increasing the dietary fat intake in these patients further increased urinary oxalate excretion. Although urinary oxalate excretion increased somewhat in colectomized patients on a high-oxalate diet, indicating an increased absorption of dietary oxalate, this increase showed no correlation either to faecal fat or bile salt excretion, or to urinary excretion of vitamin B12. The result are consistent with the "solubility theory". A diet low in fat and oxalate and high in calcium is recommended in patients with hyperoxaluria.