**1.3 Types of AKI: pre-renal vs. intrinsic vs. post-renal**

AKI can be broken up into pre-renal, intrinsic, post-renal causes. Pre-renal is caused when the kidney has ischemia due to decreased generalized perfusion or specifically to the kidney. This can occur through many processes such as hypovolemia, hypotension, hemorrhage, acute heart failure exacerbation, ACE inhibitor use etc.

Intrinsic renal disease can be caused by many varied factors. Renal vascular disease can affect small and large vessels within the kidney. These can be caused by vasculitis, microangiopathic and hemolytic anemias, malignant hypertension, etc. Intrinsic disease can also be glomerular disease that can be primary or secondary to systemic disease. This can cause nephritic or nephrotic pattern of disease. Tubular or interstitial can cause intrinsic disease that causes AKI, also known as ATN, these are caused by ischemic or nephrotoxic exposure, such as medications or contrast dye.

Lastly, post-renal disease is obstructive and can be anywhere in the urinary tract. This can be due to prostatic disease, nephrolithiasis, cancer, etc.
