Nephrolithiasis, also called renal (or urinary) calculi, is a condition in which kidney stones form from crystals that separate out of the urine in the urinary tract (1). Renal calculi begin as microscopic crystalline mineral deposits that enlarge in the kidney to visible fragments that are often painful to pass.

 

The biochemical abnormalities that contribute to the development of renal calculi are high urinary concentrations of crystal-forming substances (e.g. calcium,