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.