Oxalate and Citrate

Inclusion Criteria:

Stone formers:

* Age 18-70
* History of at least one calcium-based kidney stone

Non-stone formers (controls):

* Age 18-70
* No history of kidney stone
* 24-hour urine oxalate within lab normal (\<50mg/day)

Exclusion Criteria:

* History of primarily uric acid, cysteine, or struvite stones.
* History of severe acid-base abnormality, very low (less than 100mg/day) or very high (greater than 1500mg/day) urine citrate.
* Any controls or stone-forming participants who cannot stop diuretic medication or alkali supplementation for the course of the study period.
* Non-stone formers and stone-formers with extreme levels of urine citrate will be excluded from this small initial study to reduce heterogeneity and remove focus from the extremes of citrate levels.