Sodium thiosulfate may be useful to prevent recurrence of calcium-containing kidney stones. It will be studied in people with high amounts of urine calcium.

The investigators study is designed as a pilot study to study the effect of STS on urine chemistries in stone formers and normal controls. It is expected to continue for a duration of 1 year and will have two groups: 20 normal controls, who are healthy subjects without known kidney disease or nephrolithiasis, and 20 subjects with documented recurrent nephrolithiasis and hypercalciuria. Patients will be recruited from Dr Goldfgarb's stone clinic at VA Hospital and controls would be voluntary participants from NYU School of Medicine. Subjects who are pregnant or nursing, taking alcohol or drugs, have known CKD or are unable to give consent would be excluded from the study. Any diuretics or citrate containing drugs would be held for a period of 2 weeks during the study period to achieve washout of the effects of those drugs on urine chemistries. Oral STS 10mmol (10ml of 25% STS) BID will be administered to both groups for 7 days; four 24 hour urine collections, 2 prior and 2 at the end of the study, would be done with all participants. A diet diary would be maintained by subjects concomitantly during the study periods. The investigators then plan to compare the two groups in terms of urine chemistries to detect any changes in these parameters with thiosulfate administration. Based on prior animal experiments and human studies with STS the investigators anticipate that it would have a favorable effect on the supersaturation of Ca oxalate/phosphate and therefore its long term use would be helpful in preventing nephrolithiasis.

Inclusion Criteria:

Control arm: no longer recruiting

Hypercalciuria arm:

• Age 18-80 years old
• history of calcium-containing kidney stones
• no history of liver, heart or kidney disease (other than kidney stones)
• Non-pregnant, non-lactating
• Able to stop diuretics for a period of 1 week

Exclusion Criteria:

• Not able to sign consent
• Not satisfying any of the above criteria