Workup-nephrolithiasis

• Non-contrast CT 97% Se, 96% Sp (ureteral dilation w/o stone suggests recent passage); U/S (Se 57%, Sp 98%) may serve as initial test in stable patient (NEJM 2014;371:1100)

• Strain urine for stone to analyze; U/A & UCx; electrolytes, BUN/Cr, Ca, PO4, PTH

• 24-h urine × 2 (>6 wk after acute setting) for Ca, PO4, oxalate, citrate, Na, Cr, pH, K, vol.