Background. Tubulointerstitial nephritis (TIN) is a syndrome that is a spectrum of acute and chronic diseases, which is histologically characterized by inflammation and damage to tubular and interstitial structures, with little influence on glomerular and vascular elements. The diagnosis is certainly based on kidney biopsy, because there is no specific and sensitive clinical and non-invasive examination.
Method. This research  was a cross-sectional study based on medical record data and histopathological data of children under 18 years old suspected tubulointerstitial involvement who had kidney biopsy with indications of nephrotic syndrome, lupus nephritis and systemic lupus erythematosus from June to October 2018. The data were analysed multivariate  analysis using chi-squared and One way Anova analysis.
Results. Of the total 39 subjects, all of the them have tubulointerstitial involvement, so it was classified as secondary tubulointerstitial nephritis, nephrotic syndrome group: focal and segmental glomerular lessions for 24 children (61,5%), nephrotic syndrome group: minor glomerular abnormality for 4 children (10.3%), glomerular disorders in systemic groups: connective tissue disorders for 11 children (28.2%). The results of multivariate analysis indicates a significant difference only in the degree of edema in each group with a value of P = 0.005 (P<0.05)
Conclusion. In our study it was shown that the degree of edema was a sensitive marker of tubulointerstitial nephritis, and the three groups of tubulointerstitial nephritis although is different  in gradations but generally there were no differences in clinical and laboratory manifestations because the process of tubulointerstitial nephritis occured together with glomerular abnormalities.