Introduction. The urolithiasis prevalence is growing steadily in almost all regions of the world, including in the Russian Federation. The study of the lithogenic substances.metabolism is of paramount importance for the appointment of competent and adequate urolithiasis treatment.

Aim. The study of the metabolism of magnesium and phosphorus in the body of patients with urolithiasis, the determination of reference points - the values of a sign, going beyond which increases the risks of one or another form of urolithiasis.

Materials and methods. Material for the study – results of the chemical composition analysis of 708 urinary calculi from 303 men and 405 women from the age of 16 to 78 years. The study was conducted retrospectively. All patients underwent an analysis of the chemical composition of urinary stone and a biochemical analysis of daily urine. Method of dividing the ranked variation series into 10 ranges was used to assess the effect of the degree of calciuria on the frequency of calculi detection. Each range had from 64 to 75 observations.

Results and discussion. The study showed the frequency of detection of calcium-oxalate and uric acid stones increases with an increase in the degree of phosphaturia. Moreover, the frequency of detection of calcium phosphate (carbonate-apatite) and struvite stones steadily decreased with increasing levels of phosphaturia. There is a steady tendency to increase the frequency of calcium-oxalate stones detection with an increase of magniuria degree. There is a steady decrease in the proportion of carbonate-apatite and struvite stones at the same time. Analyze the frequency of uric acid urinary stones occurrence depending on the degree of magniuria showed no statistically significant relationship.

Conclusion. Monitoring the level of excretion of phosphorus and magnesium in the urine is important during anti-relapse urolithiasis treatment.