Nephrolithiasis

Pt with h/o low fluid intake, congenital kidney deformity, primary hyperthyroidism, and DM/gout due to excess sweetened beverage consumption presents with acute onset, paroxysmal flank pain. Flank pain is unilateral and episodes of severe pain generally last 20-60 minutes. ROS positive for N/V, dysuria, and urinary urgency. Reports personal h/o malabsorptive bariatric surgery and family h/o nephrolithiasis. Severe, unilateral CVA tenderness on exam.

  • Pregnancy test negative

  • Microscopic hematuria on urinalysis

  • Low-dose CT with contrast shows hydronephrosis, presence of stone

    • Stone <10 mm

      • Administer indomethacin 75 mg BID, tamsulosin 0.4 mg daily, and strain urine with voids

      • Consult urology if pt requires hospitalization or stone does not pass within 3 weeks in the outpatient setting

    • Stone >10 mm: Administer ketorolac 15 mg q6 hours and consult urology

  • Pt advised to keep stone upon passage

  • Send stone for analysis

Notes

  • Kidney stone types

    • Calcium stones (80%)

      • Calcium oxalate: More common and increased risk with malabsorptive bariatric surgery, e.g. Roux-en-Y

      • Calcium phosphate: Less common than calcium oxalate

    • Struvite (magnesium ammonium phosphate)

    • Uric acid

    • Cysteine

  • Differential diagnosis to consider

    • Ruptured aortic aneurysm

      • Microscopic hematuria may be present

      • Verify stable BPs to rule out diagnosis

    • Ectopic pregnancy

      • Rule out with pregnancy test

      • Consider pelvic ultrasound if pregnancy test is positive

    • Other gynecologic issues can also be ruled out with ultrasound, e.g.

      • Ruptured ovarian cyst

      • Ovarian torsion