Clinical utility of tubular markers in kidney disease: a narrative review

Background and Objective: Various tubular markers have been established for the diagnosis of kidney diseases and evaluation of treatment efficacy. Currently, there are limited treatments available for advanced kidney disease. Therefore, early identification of patients at high risk of progression to end-stage renal disease (ESRD) is necessary for the provision of appropriate treatment at an early phase. The present review focuses on newly established urinary tubular markers, i.e., urinary [tissue inhibitor of metalloproteinases-2 (TIMP-2)]*[insulin-like growth factor binding protein-7 (IGFBP7)] and L-type fatty acid binding protein (L-FABP). Methods: A literature search of the electronic databases MEDLINE (January 2014 to February 2022) was conducted using search terms of “urinary [TIMP-2]*[IGFBP7]”, “urinary L-FABP”, “kidney disease”, and “COVID-19”. Original articles, which were written in English and show clinical usefulness of urinary [TIMP-2]*[IGFBP7] or urinary L-FABP, were mainly reviewed. Key Content and Findings: These proteins are expressed in human tubules and are reported to have renoprotective functions against kidney disease. In 2014, the U.S. Food and Drug Administration approved the clinical application of NephroCheck, measuring urinary [TIMP-2]*[IGFBP7], for the diagnosis of acute kidney injury (AKI). Notably, the usefulness of urinary L-FABP in AKI, chronic kidney disease (CKD), diabetic kidney disease, aging, and coronavirus disease 2019 (COVID-19) has been widely reported. Furthermore, various methods have been established for the easy, rapid, and highly sensitive measurements of c in various situations. In 2011, urinary L-FABP was approved by the Ministry of Health, Labor and Welfare in Japan. Conclusions: Early utilization of an accurate marker may improve the prognosis of kidney disease and patient survival. © Journal of Laboratory and Precision Medicine. All rights reserved.