Pathogenesis

The underlying pathology is not fully understood, however:

• clinical setting of circulatory disturbance suggests a problem with renal perfusion
• in animal models, occlusion of renal artery by a clamp or infusion of noradrenaline into the renal artery produces laboratory "ATN"

The renal medulla is often most severely affected in acute tubular necrosis - this may be due to interruption in the perfusion of what is normally a relatively hypoxic part of the kidney. In addition, renal arterioles are prone to excessive vasoconstriction.

There are two phases of ATN described:

• an initial oliguric phase
• a polyuric phase, during which the kidney produces large volumes of urine and gradually recovers its ability to concentrate urine.