Urinary excretion of tryptophan, lysine, trimethyllysine, sarcosine, choline and 4-pyridoxic acid in urolithiasis

Introduction. The role of the organic matrix in urinary stones genesis in urolithiasis patients is still unclear. The presence of a large amount of protein in the urinary stones matrix suggests the participation of the protein matrix in lithogenesis. Research of the amino acids spectrum in urine is of great interest so far as amino acids are the part of the matrix proteins of the urinary stone.

Material and methods. We analyzed urinary excretion of the following amino acids and low molecular weight compounds: tryptophan, lysine, trimethyllysine, sarcosine, choline and 4-pyridoxine acid. We used ultra-performance liquid chromatography in combination with a TQD mass spectrometer.

Results. A higher level of excretion of choline and sarcosine is typical for patients with oxalate stones, compared with healthy people. Uric acid stone patients have high concentration of choline and extremely increased concentration of trimethyllysine in the urine unlike healthy individuals. Very low concentration of trimethyllysine, choline, sarcosine and higher excretion of tryptophan are specific for oxalate urolithiasis, in contrast to urate stone patients.

Conclusion. The intensity of amino acids and low molecular weight compounds urinary excretion has characteristic features in patients with various types of urolithiasis and healthy individuals. Indicators of excretion of these amino acids and low molecular weight substances can serve as criteria for the activity of oxalate or urate lithogenesis along with the known metabolic lithogenic factors of urine. We can use it as additional target indicators to assess the success of anti-relapse treatment.