What are renal calculi or kidney stones?
Stones or calculi, the medical term for which is lithiasis, are solid masses of variable size that form in the urinary system due to an accumulation of minerals that are found in urine. The composition of the stones can be quite varied, although they are most commonly comprised of calcium oxalate monohydrate or dihydrate, calcium phosphate, magnesium ammonium phosphate, calcium phosphate apatite, uric acid or cystine.
Small stones or those in the process of forming are typically asymptomatic and excreted spontaneously. It is very rare that they require treatment, but when they become lodged somewhere in the urinary system they can cause pain (nephritic colic) or block the flow of urine. In cases where spontaneous expulsion is not possible, there are various options for fragmenting and/or extracting the stones: