RELATIONSHIPS BETWEEN HYPERHOMOCYSTEINEMIA AND THE FUNCTIONAL STATE OF THE KIDNEYS IN CHILDREN WITH IMPAIRED PURINE METABOLISM

Among the modified risk factors for chronic kidney disease hyperhomocysteinemia (HHC) and hyperuricemia (HU) play an important role in the development of the cardiorenal continuum. The purpose of the research was to study the relationship between HHC and the functional state of the kidneys in children with impaired purine metabolism. Materials and methods used: a single-center one-stage (cross-sectional) study was conducted in 54 pediatric patients aged 9 to 15 y/o with purine metabolism disorders (in the form of isolated HU or in combination with hyperuricosuria) in Feb. 2017 - March 2021. The level of homocysteine in the blood serum was determined by enzyme immunoassay. Evaluated clearance, excreted fraction, filtered volume and reabsorption of uric acid; the glomerular filtration rate (GFR) was calculated. The two groups were distinguished: the [main] Group 1 of 26 children with HHC; and the [comparison] Group 2 of 28 children with normal homocysteine levels. Results: the frequency of diagnosis of HHC among the examined was 47.8%, which is almost 5 times higher than in the population. In the main group, the analysis of Spearman's rank correlation revealed a positive statistically significant correlation between the level of homocysteine and uric acid: Rs=0.32, p=0.048. In this group, the clearance of uric acid, its excreted fraction and filtered volume were statistically significantly lower, while reabsorption and GFR were higher relative to the comparison group. The daily excretion of uric acid directly correlated statistically significantly with its clearance (Rs=0.71, p<0.001) and excreted fraction (Rs=0.66, p=0.004) and inversely significantly correlated with the level of its reabsorption (Rs=- 0.66, p=0.004). Statistically significant direct correlation of blood homocysteine and creatinine levels (Rs=0.38, p=0.020) and inverse correlation with uric acid excretion (Rs=-0.38, p=0.020) were obtained. Conclusion: in children with impaired purine metabolism, HHC is associated with the early formation of tubular dysfunction, which is evidenced by a statistically significant decrease in the clearance of uric acid, its excreted fraction and filtered volume. The increase in GFR in this case probably reflects the formation of hyperfiltration as the initial stage of metabolic renal damage.