Type of renal stone formed in a patient with regional enteritis
## **Core Concept**
Regional enteritis, also known as Crohn's disease, is a type of inflammatory bowel disease (IBD) that can lead to malabsorption and changes in bowel habits. One of the complications of this condition is the formation of certain types of kidney stones due to the altered intestinal absorption.
## **Why the Correct Answer is Right**
The correct answer, **C. Oxalate stones**, is right because patients with regional enteritis (Crohn's disease) often have fat malabsorption. When fat is not absorbed properly in the intestine, it binds to calcium, making less calcium available to bind with oxalate. As a result, free oxalate is absorbed in the colon and excreted by the kidneys, increasing the concentration of oxalate in the urine. High urinary oxalate levels increase the risk of forming **oxalate stones**, specifically calcium oxalate stones.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while uric acid stones can form in patients with gastrointestinal diseases, they are more commonly associated with conditions that lead to an increase in uric acid production or decreased uric acid excretion, not directly with malabsorption issues seen in Crohn's disease.
- **Option B:** This option is incorrect because struvite stones are typically associated with urinary tract infections (UTIs) caused by certain bacteria that split urea, increasing the pH of the urine and leading to the formation of magnesium ammonium phosphate stones.
- **Option D:** This option is incorrect because cystine stones are associated with a genetic disorder called cystinuria, which leads to excessive excretion of cystine and other dibasic amino acids in the urine.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that patients with Crohn's disease are at increased risk of developing **calcium oxalate kidney stones** due to fat malabsorption leading to increased urinary oxalate excretion. This association is critical for understanding the pathophysiology and managing complications of Crohn's disease.
## **Correct Answer:** C. Oxalate stones