Crohn's disease is definitely a difficult problem to live with. The multiple areas of concern in this disease make it hard to manage. With respect to your particular questions, I will address them in a brief understandable way.
First, the issue of stone formation is a known process in individuals with inflammatory bowel disease, and specifically in Crohn's. Patients can have malabsorption of fat and subsequent increased absorption of oxalate, a big culprit in calcium oxalate stone formation. Diarrhea leads to dehydration, another predisposing factor. Such patients also tend to have low levels of magnesium and citrate in their urine (hypomagnesuria and hypocitraturia respectively). This is due to the malabsorption (poor absorption problem that Crohn's patient suffer from ), as well as kidney function with respect to how it handles the citrate element. When magnesium and citrate are low or not present in adequate amounts in the urine, then insoluble salts such as calcium oxalate form, which in turn collect and organize to form kidney stones. The use of magnesium oxide or magnesium citrate is known to help in the treatment of patients with calcium oxalate stones.
Second is the issue of your right non-functional kidney. In Crohn's patients the predominant area of involvement of inflammation is in the terminal ileum. This is at the end of the small intestine and just before the beginning of the large intestine. It happens to be in the right side of abdomen near an area called retroperitoneum which is where the right ureter is (ureter is the tube that carries the urine out of the kidney and drains into the bladder). Because of the chronic inflammation or possible abcess formation at the terminal ileum due to Crohn's there is local swelling and subsequent compression on the right ureter. There also will exist fibrosis and scar tissue formation in the tissue surrounding the ureter. Any or a combination of these processes may be present in a patient. The final result is the gradual and chronic blockage of the right ureter which in turn leads to loss of kidney function on that side. The urinary/urologic symptoms are often not present, therefore allowing this process to go on unnoticed. It is commonly discovered incidentally, as in your case. This sometimes may happen on the left side as well, as a result of significant inflammatory changes involving the colon.
As far as how much function will be regained on the right side, is hard to know. Depending on the amount of residual function and whether or not the blockage on the right side could be removed the right kidney may be completely non-functional vs. possibly having a reasonable restoration of function. Your urologist may decide to order a renogram(a radiographic examination) to decide about the percent remaining function. Anything less than 20% is usually too low, but this has to be put in the context of a given patient's overall profile. I wish you the best of all outcomes. You must discuss all these with your urologist.
This information is provided for general medical educational purposes only. Please consult your physician for diagnostic and treatment options pertaining to your specific medical condition. More individualized care is available at the Henry Ford Hospital and its satellites (1 800 653-6568).
*keyword: Crohn's disease and urologic manifestations