Role of renal sodium retention in children with nephrotic syndrome

Background. Among childhood kidney diseases, nephrotic syndrome (NS) occupies a special position. This is a group of symptoms characterized by severe proteinuria, hypoalbuminemia, edema, and hyperlipidemia. The incidence of NS in pediatric nephrology remains significant, and research on the formation of nephrotic edema and its treatment continues. The fact that the literature often discusses the relationship between edema syndrome and the morphological type of the disease and sodium retention by the kidneys once again confirms the relevance of the problem.

Objective. Evaluation of the role of renal sodium retention in overcoming edema syndrome in children with nephrotic syndrome.

Material and methods. The survey of 487 children aged 3 to 18 years, including 208 boys and 279 girls, who received treatment with a diagnosis of nephrotic syndrome, was conducted in the Nephrology Department of the Children's National Medical Center from 2021 to 2024. The average age of the children was 11.7 years. The diagnosis of NS was made in all children based on clinical edema syndrome, massive proteinuria (more than 3 g/L per day), hypoalbuminemia and hypercholesterolemia.

Results. The results of the study revealed that fractional excretion of sodium (FENa) was 0.40±0.35%, UNa/Ucrea in children from the control group was 9.04±6.76, UK/UNa+UK – 041±017. These indicators were taken as a standard for patients in the NS group who eat dietary products with a low sodium content. In patients in the steroid-dependent nephrotic syndrome (SDNS) group, FENa (0.09±0.09%) was very low, UNa/Ucrea (2.83±3.31) was the lowest, and UK/UNa+UK (0.76±0.06) was the highest. These markers were significantly different from the markers of other cohorts (p<0.01). During the treatment, 1 patient developed edema syndrome, this indicator was 0.6 (0.42) against the background of low FENa and UK/UNa+UK indicators reaching 0.1 and 2.68%, respectively.

Conclusion. The revealed differences in ultrasound parameters are combined with differences in the urine excretion of electrolytes: in children with steroid-resistant NS, the fractional excretion of sodium is significantly higher, and the potassium content in the urine is lower than in children with SDNS, which confirms the prevalence of a hypervolemic state in the first group and a hypovolemic state in the second ones.