BackgroundThe objective of this study was to establish age-dependent values for urinary renalase/creatinine (renalase/Cr) ratio in healthy children and adolescents.MethodsThe study was conducted on a random sample of 157 healthy children and adolescents (0.1–17.9 years) divided into six age groups in 3-year intervals. Urine renalase concentration was measured using an enzyme-linked immunosorbent assay (ELISA) kit (Uscn Life Science, Wuhan, China).ResultsWe analyzed median urine renalase/Cr ratio in particular age groups with the use of analysis of variance (ANOVA). Renalase/Cr levels were significantly higher in the youngest children < 3 years in comparison with other age groups (4.07 ng/mg Cr, p < 0.05). There was a statistically significant negative correlation between urine renalase/Cr and body mass index (BMI) Z-score (r = −0.22, p < 0.05) and both systolic (r = −0.22, p < 0.05) and diastolic (r = −0.21, p < 0.05) blood pressure. We constructed the reference renalase/Cr percentiles according to age in 3-year intervals.ConclusionsTo the best of our knowledge, this study is the first to present reference values of urine renalase excretion in a healthy pediatric population. Further studies should concentrate on the influence of increased blood pressure or obesity on urine renalase excretion in children and teenagers.

BackgroundLipid disorders are known to be linked to disturbance in oxidative reactions and play an important role in the progression and complications of idiopathic nephrotic syndrome (INS).AimsThe aim of this study was to assess oxidized low-density lipoprotein (oxLDL), high-sensitive C-reactive protein (hs-CRP) serum concentrations and other parameters of lipid metabolism in children with INS during relapse and remission of proteinuria.MethodsThe examination was performed on 23 children and adolescents diagnosed with INS. Reference group consisted of 22 participants. The study was carried out twice: in the relapse of INS (A) and in remission of proteinuria during glucocorticoid treatment (B).ResultsOxLDL was higher in INS patients, in both examinations when compared with reference participants. hs-CRP showed no differences between nephrotic and healthy children. We found higher concentration of oxLDL in children, who where frequent relapsers. Cholesterol, triglycerides/high density lipoprotein cholesterol and platelets were higher in INS patients (both A and B) in comparison with healthy children.ConclusionsWe observed presence of pro-atherogenic lipid profile in INS. Elevation of oxLDL may reflect increased oxidative stress and higher risk of atherosclerosis in INS, therefore it seems to be relevant to find patients of risk of atherosclerosis to consider lipid lowering treatment with antioxidants.