National Institutes of Health
- The primary NIH organization for research on Kidney Stones is the National Institute of Diabetes and Digestive and Kidney Diseases
A kidney stone is a solid piece of material that forms in the kidney from substances in the urine. It may be as small as a grain of sand or as large as a pearl. Most kidney stones pass out of the body without help from a doctor. But sometimes a stone will not go away. It may get stuck in the urinary tract, block the flow of urine and cause great pain.
The following may be signs of kidney stones that need a doctor's help:
NIH: National Institute of Diabetes and Digestive and Kidney Diseases
References and abstracts from MEDLINE/PubMed (National Library of Medicine)