Kidney Stones: Symptoms, Causes, and Treatment

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Barbara K. Hecht, PhD

One in every 20 people develop a kidney stone at some point in their life. Kidney stones, known medically as renal calculi, form within the kidney itself or in other parts of the urinary tract. The condition of having kidney stones is termed nephrolithiasis or urolithiasis.

Kidney stones may produce severe symptoms. People who have kidney stones report the sudden onset of excruciating cramping pain in their side, groin, or abdomen. Changes in body position do not relieve this pain. It may be so severe that it is accompanied by nausea and vomiting. Kidney stones also characteristically cause blood in the urine. If infection is present in the urinary tract along with the stones, there may be fever and chills.

Kidney stones form when there is a decrease in urine volume or an excess of stone-forming substances in the urine. The most common type of kidney stone contains calcium in combination with either oxalate or phosphate. Other chemical compounds that can form stones in the urinary tract include uric acid and the amino acid cystine.

Dehydration through reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones. Obstruction to the flow of urine can also lead to stone formation. Kidney stones associated with infection in the urinary tract are known as struvite or infection stones.

Men are especially likely to develop kidney stones, and whites get them more often than African Americans. The prevalence of kidney stones begins to rise when men reach their 40s and continues to climb into their 70s. People who have already had more than one kidney stone are prone to develop more stones.