Metabolic risk factors and urinary stones formation. VII: Uricosuria lithogenic features in men and women.

Abstract

Introduction. Hyperuricosuria usually considered as the main metabolic factor in the formation of uric acid stones, but this issue remains unclear. Gender differences in the prevalence of urolithiasis (UL) indicate the need for a more detailed study of the lithogenic properties of uricosuria and its role in the development of various metabolic types of UL. In this study, was investigated the effect of varying degrees of uricosuria in men and women with UL on metabolic parameters and the frequency of detection of urinary stones of different chemical composition. Materials and methods. A total of 982 patientsа with UL (439 men and 543 women aged 18 to 79 years)were examined. To assess the lithogenic activity of uricosuria in men and women with UL, the values of uric acid excretion (in mmol/day) were ranked in ascending order and divided into 10 equal parts (ten 10%-х percentilesей). In each of the ranges, the percentage distribution of types of urinary stones and biochemical parameters of urine and blood were determined. Results. As the degree of uricosuria increased from minimum to maximum values in men and women, there were no differences in the percentage distribution of uric acid stones. The different orientation of the processes of urate lithogenesis is noted, which was manifested in uricosuria above 3.48 mM/day by the accumulation of anhydrous uric acid in the stones in women 1.47 times greater than in men, in whom the proportion of uric acid in the stones, on the contrary, decreased by 1.36 times. It was found that uricosuria above 3.48 mM/day was accompanied by activation of oxalate lithogenesis rather than uric acid: the incidence of oxalate stones in men increased by 1.55 times (p=0.0025), and in women by 2.16 times (p=0.0013). At the same time, the proportions of the oxalate component in the stones of male and female patients, respectively, increased, mainly due to the wevellite component. An increase in uric acid excretion over 3.48 mM/day led to a relative decrease in the frequency of detection of carbonatapatite stones in men by 1.85 times (p=0.0104), and in women by 2.0 times (p=0.0153). With increasing uricosuria, both men and women experienced an almost linear increase in the levels of calcium, phosphate, and magnesium excretion (p<0.0001). The blood phosphate content in women was on average 7-11. 6% higher than in men, and uric acid was lower by 8.5-16.0% for almost all values of uricosuria. Calcemia levels in men and women did not have statistically significant differences. for all values of uricosuria. Men in the age groups from 30-39yr to 60-79yr have a higher uric acid excretion than women, which also corresponds to a higher incidence of oxalate stones in men, exceeding this indicator in women in all age groups by 2.5 -1.8 times (p<0.05). The formation of uric acid stones is observed in men of an earlier age than in women, namely from the age of 18-29yr, while in women the formation of stones of this type is detected only from the age group of 40-49yr and older. Conclusion. Characteristic property of uricosuria of various degrees is its different ability to influence the dynamics of metabolic parameters of excretion and lithogenesis of calcium stones (oxalate and phosphate stones) in men and women in the absence of a noticeable effect on the lithogenesis of uric acid stones, which should be taken into account when conducting personalized metaphylaxis of urolithiasis.