Crohn's and kidney stones: what should you know?

The bowel and kidneys handle fluid and salts together. Ongoing diarrhoea can reduce fluid available to urine, while changes in digestion and absorption may alter substances that help form crystals. A stone can cause waves of severe flank or abdominal pain, nausea, blood in the urine, painful urination or difficulty passing urine. These symptoms can overlap with a Crohn's flare, so they need careful assessment.

A stone is not the only explanation for urinary pain. Infection, dehydration and other urinary conditions can feel similar. A clinician may ask about stool losses, fluid intake, previous stones, medicines and family history.

Follow your Crohn's treatment plan and replace fluids regularly, unless a clinician has given you a fluid restriction. During diarrhoea, ask a pharmacist or doctor about suitable oral rehydration. Do not deliberately force large volumes if you are vomiting or have kidney or heart problems; seek personalised advice.

A GP consultation can assess pain and urine symptoms. An abdominal ultrasound may help look for a stone or blockage, although other tests may sometimes be needed. Keep a note of urine changes, pain location, fever, vomiting and how much you can drink.

Seek urgent care for severe or persistent flank pain, fever or chills with urinary symptoms, repeated vomiting, faintness, inability to drink, very little or no urine, or pain with a single functioning kidney or known kidney disease. A blocked urinary system with infection can become serious and should not be managed at home.

Could my symptoms be a stone, dehydration, infection or Crohn's activity? Do I need urine tests, blood tests or an abdominal ultrasound? How much fluid is appropriate for me? Could any medicine or bowel surgery affect my stone risk? What symptoms mean I should return urgently?