A 32-year-old man comes to the emergency room (ER) because of acute onset left flank pain, hematuria and vomiting. His pain is relieved with analgesics in the ER. He has a history of abdominal pain due to Crohn disease, but that pain was always in the right lower quadrant and was never this severe. His temperature is 36.8°C (98.2°F), blood pressure is 120/65 mm Hg, pulse is 110/min and respirations are 16/min. Chest auscultation is clear. Abdomen is soft and mildly tender over the left flank. He has no rebound or rigidity. Bowel sounds are decreased. A laparotomy scar is present in right lower quadrant. Which of the following is the most likely cause of his symptoms?

Question

A 32-year-old man comes to the emergency room (ER) because of acute onset left flank pain, hematuria and vomiting.  His pain is relieved with analgesics in the ER.  He has a history of abdominal pain due to Crohn disease, but that pain was always in the right lower quadrant and was never this severe.  His temperature is 36.8°C (98.2°F), blood pressure is 120/65 mm Hg, pulse is 110/min and respirations are 16/min.  Chest auscultation is clear.  Abdomen is soft and mildly tender over the left flank.  He has no rebound or rigidity.  Bowel sounds are decreased.  A laparotomy scar is present in right lower quadrant.  Which of the following is the most likely cause of his symptoms?

Quizplus · Accepted Answer

The patient described is experiencing symptoms consistent with nephrolithiasis, which classically presents with flank pain and hematuria frequently accompanied by nausea and vomiting. Patients with Crohn disease, or any other small intestinal disorder resulting in fat malabsorption, are predisposed to hyperoxaluria. Oxalate is obtained from the diet and is a normal product of human metabolism. Symptomatic hyperoxaluria is classically the result of increased oxalate absorption in the gut. Under normal circumstances, calcium binds oxalate in the gut and prevents its absorption. In patients with fat malabsorption, calcium is preferentially bound by fat leaving oxalate unbound and free to be absorbed into the bloodstream. Failure to adequately absorb bile salts in states of fat malabsorption also cause decreased bile salt reabsorption in the small intestine. Excess bile salts may damage the colonic mucosa and contribute to increased oxalate absorption. (Choice A) Bile salt recycling and fatty acid absorption are decreased in Crohn disease. (Choices C and D) Hypercalciuria, which may be idiopathic or may result from hyperparathyroidism, excessive calcium and vitamin D ingestion, dehydration or prolonged immobilization, predisposes to calcium stone formation. (Choice E) Recurrent urinary tract infections, particularly by Proteus species, predispose to struvite stone formation. Struvite stones may eventually grow to fill the entire renal pelvis, at which point they are known as "staghorn" calculi. Educational objective: Oxalate absorption is increased in Crohn disease and all other intestinal diseases causing fat malabsorption. Increased absorption is the most common cause of symptomatic hyperoxaluria and oxalate stone formation.

A 32-Year-Old Man Comes to the Emergency Room (ER) Because