**4.7 Urinary biomarkers**

Markers of microbial translocation, inflammation (IL-6), and intestinal damage as well as fatty acid-binding proteins (FABP) and glutathione S-transferases (GSTs), which can be determined using ELISA technics, are suggested as significant biomarkers demonstrating intestinal epithelial cell damage. Fatty acid-binding proteins (FABPs) are small intracellularly or membrane-localized proteins released in the extracellular space in their soluble extracellularly from early after a cell or tissue damage. There are three main types of FABP. Liver-type FABP, intestinal-type FABP, and ileal FABP. During intestinal cell damage, intestinal-type FABP (I-FABP) is released from the enterocytes in the systemic circulation and excreted through the kidney [98]. Therefore, it has been suggested that I-FABP is an early biomarker to detect impairment of IB and injury in sepsis [99–101].

GSTs are cytosolic enzymes released when the cell membrane is damaged and play a crucial role in the detoxification of xenobiotics. Hence, α-GSTs are introduced as intestinal biomarkers [95].
