Effect of macromolecules and of sodium dodecyl sulphate upon precipitation of calcium oxalate and phosphate from whole urine.

Different proportions of mixtures of whole urine and its ultrafiltrate were evaporated to 1,250 mosm/kg to study crystal formation of calcium oxalate at pH 5.3 and calcium phosphate at pH 6.8. At both pH values there was a direct linear relationship between proportion of whole urine and crystal formation. When sodium dodecyl sulphate was added to whole urine before evaporation, calcium oxalate and calcium phosphate crystal formation were reduced to 64.3 and 53% respectively of the values of whole urine. This favours the proposition that crystal formation is promoted by polymeric uromucoid.