Crohn’s Disease Raises Risk of Kidney Stones, Dehydration and Rare Serious Complications

Crohn’s disease can affect kidney health, and kidney complications are more common than in the general population. Many of these complications are preventable — or at least manageable — by recognizing risks early and taking steps to protect kidney health in the long run.

People with Crohn’s disease face a higher risk of developing kidney stones, especially calcium oxalate stones. Kidney stones are common in Crohn’s disease because diarrhea, dehydration, and difficulty absorbing fat and certain nutrients change the chemistry of the urine, which makes stone-forming substances like oxalate and uric acid more likely to crystallize.

When inflammation from Crohn’s interferes with fat absorption in the gut, unabsorbed fat binds to calcium. Normally, calcium would bind to oxalate and help remove it from your body. But when calcium is used up by fat, oxalate is left free to be absorbed into your bloodstream. From there, it travels to your kidneys, where it can crystallize and form stones. Crohn’s can also reduce helpful gut bacteria that degrade oxalate, leaving more oxalate free for absorption.

Dehydration is most likely during a Crohn’s disease flare or after bowel surgery, and acute kidney injury is a frequent cause of a hospital readmission post-op. Diarrhea makes urine more concentrated and acidic, both of which increase the risk of uric acid stone formation.

Some of the medications used to manage Crohn’s disease require monitoring for possible kidney-related side effects. Despite the low risk, it’s standard practice for doctors to monitor kidney function with periodic blood and urine tests if a patient is on 5-ASAs or other potentially kidney-active therapies long-term. NSAIDs like ibuprofen can reduce kidney blood flow and contribute to acute kidney injury or worsening chronic kidney disease, especially when someone is already dehydrated, and they can also worsen gut inflammation, especially in higher doses.

Advanced therapies like biologics are not strongly linked to kidney damage, but very rare complications tied to kidney damage have been reported. It is still important for clinicians to review other kidney risk factors, monitor labs periodically, and investigate any new changes in kidney function while a patient is on these therapies.

While it’s relatively uncommon, in more severe cases of Crohn’s disease, fistulas or severe inflammation can sometimes involve or press on the tubes that drain the kidneys or connect to the bladder. Chronic gut inflammation, imbalance of intestinal bacteria, and increased intestinal permeability drive the conditions for glomerulonephritis. It’s a rare complication of Crohn’s disease and is becoming less common with the development of better medications to treat Crohn’s.

Protecting kidney health in Crohn’s disease comes down to hydration, nutrition, monitoring, and discussing kidney risks early with a healthcare team.