Alpha Glutathione S-Transferase (αGST) is a detoxification enzyme that catalyzes the conjugation of glutathione with a variety of endogenous and exogenous toxins. This enzyme is part of a mammalian GST super-family consisting of cytosolic dimeric isoenzymes that have been assigned to at least 6 classes: Alpha, Mu, Pi, Theta, Zeta and Omega. Urinary αGST levels are a specific indicator of proximal tubular function and injury. Typically, normal/healthy urine does not contain measurable amounts of αGST, whereas elevated levels correlate closely with the time course and severity of renal injury.