When a patient needs a metabolic evaluation for kidney stones the twnety-four hour urine should include at minimum:
- Uric Acid
- Urea nitrogen
Urine oxalate over 90 mg/day should trigger an evaluation for enteric hyperoxaluria or primary hyperoxaluria.
Hypocitraturia is defined as a citrate below 325mg/day. Hypokalemia can trigger hypocitraturia (along with metabolic acidosis) so be careful when prescribing a thiazide for hypercalciuria, the resulting hypokalemia could surpress citrate and increase rather than lower the risk of developing a kidney stone.
While bowel disease is usually associated with calcium oxalate stones, patients often have decreased urine pH which predisposes them to uric acid stones.