Influence of the lysine on the calcium oxalate renal calculi.

Plasma levels and urinary excretions of amino acid lysine were estimated by high-performance liquid chromatography in 15 control subjects and 56 stone formers (SFs) with calcium oxalate (CaOX) urolithiasis. Data demonstrated clearly that there is a general tendency toward decreased lysine's excretions in above 40% of SFs. Moreover, it was found that DL-lysine, a normal physiological constituent of urine, acts at increased concentrations as a dissolving agent with respect to CaOX and CaOX calculi. The kinetics of dissolution of crystalline calcium oxalate calculi in physiological solutions containing DL-lysine at different concentrations is studied, using the change in the Archimedean weight of samples immersed in the solution. The possible effect of lysine as a natural regulator of CaOX supersaturation and crystallization in human urine is also discussed.

Hippuric acid as a significant regulator of supersaturation in calcium oxalate lithiasis: the physiological evidence.

At present, the clinical significance of existing physicochemical and biological evidence and especially the results we have obtained from our previous in vitro experiments have been analyzed, and we have come to the conclusion that hippuric acid (C6H5CONHCH2COOH) is a very active solvent of Calcium Oxalate (CaOX) in physiological solutions. Two types of experiments have been discussed: clinical laboratory analysis on the urine excretion of hippuric acid (HA) in patients with CaOX lithiasis and detailed measurements of the kinetics of the dissolution of CaOX calculi in artificial urine, containing various concentrations of HA. It turns out that the most probable value of the HA concentration in the control group is approximately ten times higher than the corresponding value in the group of the stone-formers. Our in vitro analytical measurements demonstrate even a possibility to dissolve CaOX stones in human urine, in which increased concentration of HA have been established. A conclusion can be that drowning out HA is a significant regulator of CaOX supersaturation and thus a regulation of CaOX stone formation in human urine. Discussions have arisen to use increased concentration of HA in urine both as a solubilizator of CaOX stones in the urinary tract and on the purpose of a prolonged metaphylactic treatment.