Unknown

Fresh urine samples from normal individuals were adjusted to pH 5.3, 6.0 or 6.8 with hydrochloric acid or sodium hydroxide. Each urine sample was divided into 4 aliquots, 2 being untreated control samples and 2 test samples containing added tartrate, magnesium or both,. Sodium tartrate was added to test aliquots to give a concentration after evaporation of 5 mmol/l and magnesium chloride to raise urinary magnesium post-evaporation by 4 mmol/l. Also sodium oxalate was added to all samples to raise the final oxalate concentration by 0.22 mmol/l. Each sample was evaporated in a rotary evaporator5 to 1250 mosmol/kg (for calcium oxalate tests) or 1050 mosmolfkg (for calcium phosphate tests). In calcium oxalate experiments, 14c-oxalate in the precipitate was measured by scintillation counting. Calcium phosphate deposits were assessed from calcium determination by atomic absorption spectroscopy. Magnesium and Tartrate shows additive Effects upon inhibition of calcium oxalate crystal formation in whole urine