[Detection of urinary organic acids by gradual titration of pH 2,0-7,4. Significance for the assessment of the litho-protective characteristic of the examined urine].

The role of organic acids in urine is not sufficiently known until today. From our detailed in vitro studies it can be concluded that some of them are highly efficacious in the inhibition of Ca-oxalate and Ca-phosphate crystal growth. Moreover, some of them showed, as acids and as salts, a strong lytic effect on stone-forming crystals and native stone-material. By the oral application to rats, concentrations preventing any precipitation out of meta- and instable Ca-oxalate solutions could be achieved. The renal excretion was controlled by the stepwise titration of preacidified urinary samples from pH 2.0 to 7.4 and the lithoprotective character of urine estimated by the Ca2+-binding capacity.