title: Clinical significance of phosphate in calcium oxalate renal stones.
abstract: We analysed calcium, magnesium, oxalate, citrate, urate and creatinine in urine and calculated risk factors in patients who had formed stones composed of calcium oxalate, and calcium phosphate, alone or as a mixture. Patients producing pure calcium oxalate stones (less than 0.1% phosphate) had a higher oxalate, and lower calcium excretion than stone-free subjects and patients forming other stone types. In contrast, patients producing calcium oxalate stones containing phosphate, even in trace amounts (greater than 0.1%) had no increase in oxalate excretion, but a higher calcium excretion than stone-free subjects. We could not correlate any computed variable (e.g. AP(CaOx) index) to stone composition. We conclude that pure CaOx stones may be the result of a high oxalate excretion, and that other calcium containing stones may have another and probably more complex aetiology, including primary precipitation of calcium phosphates.
authors.affiliation: Department of Clinical Chemistry, University Hospital of Linköping, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Ohman
authors.forename: L
authors.initials: L
authors.lastname: Larsson
authors.forename: H G
authors.initials: HG
authors.lastname: Tiselius
mesh_terms: D002129:Calcium Oxalate / Q000652:urine*; D002130:Calcium Phosphates / Q000652:urine*; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry*; D008297:Male
chemical_list: D002130:Calcium Phosphates; D002129:Calcium Oxalate