Kidney stones are very common. They affect 3-5% of the population in the United States. Many people are hospitalized for the treatment of kidney stones and some may die. Better understanding of what causes kidney stones is useful in both the treatment and prevention of kidney stones. However, exactly what causes kidney stones is unknown.

The most common type of kidney stones contains calcium, which sometimes is attached to a part of the kidney important in producing the final urine, called the papilla. The investigators have noticed that persons who form kidney stones seem to have more papilla with stones attached. They propose to study these areas of the papilla, called Randall's plaques (named after their discoverer), in patients undergoing surgery for kidney stones.

In order to attempt to explain the pathogenesis of renal calculi, the investigators videotape and document the location and characteristics of each stone, papillae and calyces. One or more small papillary biopsies are taken for analysis to help determine the point of origin of the kidney stone and histological studies are undertaken to determine tissue differences amongst different types of stone formers. Approximately one month after surgery, metabolic studies are undertaken to further review potential causes of stone formation.

Inclusion Criteria:

• Patients of Methodist Urology in Indianapolis, IN who are undergoing endoscopic procedures for nephrolithiasis or other urologic disease.
• Upper urinary tract endoscopic or PERC procedure for kidney stones removal
• General medical health allowing surgical procedure
• Ability to complete all the necessary components of the study
• Able to sign an informed consent

Exclusion Criteria:

• Poor general medical health
• Bleeding diathesis
• Inability or unwillingness to comply with post-surgical follow-up