Obtain a single 24-hr urine panel⁹ for stone risk factors

⁹ Tailored testing may be considered (eg, pure uric acid stones: check urine pH, uric acid, Cr; Ca++ stones: expanded panel). Check for relevant change in urinary Ca++, oxalate, uric acid, cystine excretion, pH, and increased urinary volume, citrate excretion. Urinary stone-forming salt super-sat is part of many 24-hr urine panels. Urine K+ can gauge med compliance. Animal protein intake markers (urine urea nitrogen, urinary sulfate) can be used to assess diet. Measure urinary cystine if cysteine stones or FHx cystinuria. Suspect 1° hyperoxaluria if urinary oxalate excretion >75 mg/day in adults w/o bowel dysfxn (refer for genetic test/specialized urine tests).<br><br>¹⁰ ADRs: hypokalemia, glucose intolerance, ↑ liver enzymes, anemia/hematologic abnl, hypercalcemia, etc., depending on drug.<br><br>
¹¹ Plain films acceptable for radiopaque stones: limited radiation, lower cost, but not as sensitive/specific as CT. Renal US preferred for most pts w/ radiolucent stone: no ionizing radiation, less costly, but not as sensitive/specific as CT. Unenhanced CT is most sensitive; can often be done w/ low-dose protocol.