Sniper is correct. Stones are more common with CD patients due to some fluid absorbtion issues in the bowel related to the inflammation and scarring. I would suggest consulting a urologist. Thereis a urine collection test they can do to determine what minerals are contributing to your stones, and then various medications and dietary changes that can greatly reduce the likelihood of them recurring. One note on allopurinol -- if you are on Imuran or 6mp for your Crohns, dosages of that and allopurinol may have to be adjusted, as they are related medications.