Hydroxycitrate (HCA) is a compound extracted from the fruit, Garcinia Cambogia. Hydroxycitrate supplements are available over the counter and are primarily promoted as a weight loss supplement. There has been recent evidence that hydroxycitrate is a potent inhibitor of calcium oxalate crystal growth and can lead to the dissolution of the crystals. The purpose of this research study is to study the effect of Hydroxycitrate (HCA) supplements on HCA urinary excretion and on urine chemistries in kidney stone formers and normal subjects.

Inclusion Criteria:

Stone formers group:

• Established diagnosis of recurrent calcium stone formers
• Ages between 18 and 80
• Subjects must be able to read and follow instructions clearly and able to do 24 hour urine collections.
• Subjects must be voluntarily willing and able to sign an informed consent form.

Control Group:

• In addition to b, c and d above, subjects must not have any known kidney disease or family history of renal stones. Inclusion would be based on information provided by participants.

Exclusion Criteria:

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