What are the chemical precursors of renal stones?
- Relatively high concentrations of salt and acid solutes determine crystalluria and stone formation.
- Calcium oxalate is most common and is supersaturated to four to five times its solubility in normal urine.
- Other precursors are calcium phosphate (hydroxyapatite) and calcium phosphate monohydrate (brushite).
- Uric acid, cystine, struvite (magnesium ammonium phosphate), and mucoprotein are undersaturated stone precursors.
- Drugs, such as ascorbic acid (conversion to oxalate) and triamterene (nidus for stone formation), also may promote renal stone formation.
