Nephrolithiasis

Abstract

A 24-year-old Hispanic woman with no medical history presents to the emergency department for the acute onset of left flank pain that radiated to the left lower quadrant. She had two episodes of non-bloody vomiting. She denied any prior episode of flank pain or nephrolithiasis, hematuria, pyuria, and dysuria. Her menstrual periods have been normal; her last menses was 7 days ago. She is in a monogamous relationship using barrier contraception. She denied sexually transmitted diseases, urinary tract infections, and any family history of kidney stones. Physical exam was notable for a non-tender left flank. Routine blood tests were unremarkable, including routine chemistries, creatinine, liver function tests, amylase, and lipase. Urinalysis revealed amber urine, specific gravity 1.020, pH 6.5, leukocyte esterase negative, nitrite negative, trace protein, five to ten white cells, and > 50 red cells per high powered field. Urine pregnancy test was negative. Stone protocol abdominal CT scan revealed a non-obstructing, 4 mm renal calculus in the distal left ureter. She received IV ketorolac and normal saline hydration with relief of her flank pain. As an outpatient, she spontaneously passed the stone. Chemical analysis revealed a calcium oxalate stone. Her primary care doctor told her to increase her urine output to at least 2 L per day and to reduce dietary sodium intake to 2,300 mg daily. Protein restriction to 0.8-1 g/kg body weight per day was also recommended.