Acute kidney injury is defined as acute kidney damage due to injury. This AKI is divided into three broad terms including: pre-renal, renal or post renal. Pre-renal is any cause that is before kidney (such as shock, or bleeding). kidney starts to retain salt and water leading to urinary osmolality more than 600 and between 900mosm/L and urinary sodium as low as 10mW. Renal type of damage includes any cause with in the kidney that can lead to damage such as vasculitis, sepsis or myeloma). In this kind of damage kidney is inadequately functioning leading to urinary osmolality of 280mosm/L and urinary sodium more than 30mM.