Crohn’s disease symptoms and complications: Kidney

In crohn’s patient other organs besides the gi tract, such as the kidney, have significant chance of being affected during advanced stages of the disease or by the medications used in treating the disease. Symptoms related to crones disease that increases the chances of kidney problems are malabsorption and dehydration. Certain crohn’s medications also arises kidney symptoms such as 5-aminosalicylates (mesalamine), sulfasalazine, and cyclosporine A or tacrolimus. Surgery of the intestine also aggravates the symptoms that promote kidney problems.

Common kidney problems related with this disease are kidney stones. Two types of kidney stones are observed most commonly in crohn’s patients: calcium oxalate stones and uric acid stones.

Calcium oxalate stones:

Patients suffering from inflammatory bowel disorder commonly develop this type of kidney stones. Symptoms for this complicated disorder include pain, nausea, vomiting and urine with blood. Crones symptoms like fat malabsorption and dehydration increase risk in Crohn’s patients to have calcium oxalate stones. Any form of increase in oxalate salt intake can cause kidney stones. In the case of crohn’s disease when the small intestine is in inflamed condition it interferes with fat absorption and fat intake in decreased. Fat remains in the intestine and binds with dietary calcium which is necessary to bind with oxalate salt. This unbound excess oxalate salt is then absorbed from the digestive tract particularly the large intestine (colon) and is likely to precipitate and form stone deposits in kidney. Crohn’s patients who have undergone resection (removal or cut off) surgery of their small intestine are more prone to facing this complicated issue. Small intestine leads to more dehydration and this in turn produces concentrated urine. Concentrated urine leads to formation of kidney stones. To treat this problem patients have to take lots of fluid and have diet containing low amount of oxalate such as juices of fruits and vegetables.

Uric acid stones:

As the name suggests this kidney stones are formed from pure crystals of uric acid. Concentrated urine is acidic in nature that is it has low pH. Crohn’s patients whose colon is inflamed or removed by surgery are most likely to develop uric acid stones. Inflamed colon results in less absorption of water and causes dehydration. This leads to concentrated urine formation which normally contains high amounts of uric acid. As this uric acid pass through the kidney they deposit and form crystals or stones. Treatment includes high intake of fluid; increasing the pH of urine (urine alkalinization) with the help of medications like acetazolamide; and allopurinol, a drug that interferes with uric acid formation in liver and decreases uric acid level in the system.

Other forms of kidney complications include the following:


This complicated anatomical disorder arises in Crohn’s patients when one of the ureter (tubes that connect kidney with bladder) becomes obstructed (constricted). Patients with an infected (inflamed) terminal small intestinal region (ileum) are mostly seen to suffer from this condition. The inflamed intestine puts pressure on the kidney and the kidney pressurizes the ureter. However due to the obstruction the urine is unable to move from the kidney to the bladder resulting in formation of scar tissues in kidney and abnormal kidney enlargement. To overcome this problem and to restore normal urine flow the neighbouring infected intestinal area and the scar tissues of kidney has to be surgically removed.


These are abnormal tube-like structures that connect the intestine with the bladder or the ureter. Fistulas are considered to be complicated Crohn’s disease symptoms and occur normally in severe cases of the Crohn’s disease. This causes frequent infections in the urinary tract and in rare cases urine may contain blood. Surgery is mostly done to remove fistulas that form in the urinary tract since medications are unable to close fistulas related to the renal area.


This is a rare, complicated symptom and is seen only in 1% of Crohn’s patients suffering from severe or long-term Crohn’s disease. This problem arises when amyloid (an abnormal protein) deposits in the kidney. Patients whose colons have been removed are more likely to face this condition.

Drug toxicity:

Drugs like the immunosuppressive drug cyclosporine can constrict blood vessels of kidney and thus change the function of kidney. Kidney toxicity can occur on long-term use of sulfasalazine and the 5- aminosalicylate drugs. All these may lead to kidney failure. Patients having these medications should frequently monitor their kidney function.
Crohn’s patients should be regularly monitored to ensure that there are no complications regarding the kidney.