Biomarkers in ureteropelvic junction obstruction Review and perspectives

Background Ureteropelvic junction obstruction (UPJO) is the most frequent congenital obstructive uropathy. Currently approximately 30-40% of UPJO patients need surgical correction; however, in 20-30% of cases the allocation to the conservative treatment group leads to deterioration in split renal function and the need for secondary surgery. In the future sensitive urinary biomarkers may have the potential to detect subclinical kidney damage and therefore provide better protection for patients from loss of renal function. Material and methods A literature search was carried out in MEDLINE. Results The urinary biomarkers monocyte chemoattractant protein-1 (MCP-1), neutrophil-gelatinase associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), epidermal growth factor (EGF), transforming growth factor beta (TGF-beta) and carbohydrate antigen 19-9 (CA 19-9) were analyzed in 24 studies between 2000 and 2022. These markers reflect tubular damage, inflammation and fibrotic remodeling in the kidneys and are elevated in the urine of UPJO patients. Urinary proteomics and metabolomics are able to predict the need for surgery in infants; however, for urinary proteomics a multicenter validation failed. Despite clinical normalization of UPJO findings, after a 5-year observation period conservatively treated patients have an abnormal urinary proteome pattern that is indicative of renal remodeling. Discussion So far, isolated markers and proteome analyses were ultimately unable to answer the question of predictive urinary markers for indications for surgery in UPJO. The reasons were small patient collectives, inclusion of patients beyond infancy and the lack of adequate control groups or postoperative data. Prospective randomized trials to precisely define the indications for surgery and to assess the long-term outcome of conservatively treated patients are therefore necessary. The protocol of the prospective multicenter COMPARE-UPS study will address these needs and will soon be available.