What Are Kidney Stones?

For Patients

If you suspect you have stones, visit your primary care provider or urologist.

If you've been diagnosed with stones and would like to be seen in the Metabolic Stone Clinic, please call (608) 263-4757.

A kidney stone is a hard, stone-like mass (also called a calculus) developed from tiny crystals that form in urine. Stones form from these small crystals, which attach to the inner surfaces of the kidney, grow into larger crystals and eventually become stones.
Size and Location
Stones can form in one or both kidneys and typically range from less than five millimeters in size to as large as 10 millimeters or more. The size of the stone, determined through imaging studies such as X-rays, determines whether an individual can spontaneously pass the kidney stone through the urinary tract or whether surgical intervention is required.
Medical Terms 
Urolithiasis, nephrolithiasis, ureteral calculi and renal calculi are medical terms used to describe stones occurring in the urinary tract and kidneys. Doctors also use terms that more precisely describe the location of the stone in the urinary tract. For example, a left ureteral stone (or ureterolithiasis) is a kidney stone lodged in the ureter connecting the left kidney to the bladder.