What is the clinical course of Acute Tubular Necrosis?
Clinically, four phases of Acute Tubular Necrosis can be described. In the initiation phase , exposure to the nephrotoxic agent, ischemia, or sepsis initiates the injury to the kidney.
In clinical practice, often there are multiple exposures whose cumulative effect results in the initiation of Acute Tubular Necrosis.
The initiation phase is then followed by an extension phase , during which there is continued cellular injury mediated by continued microvascular injury and the activation of inflammatory mediators despite the fact that the triggering exposure has resolved.
This is then followed by a maintenance phase , which may last from days to 6 weeks or longer. During the maintenance phase, the GFR remains markedly depressed and is often accompanied by oliguria.
During this phase, patients are often dependent on some form of renal replacement therapy (dialysis or continuous hemofiltration). With time, the patient may enter the recovery phase , during which time there is regeneration of the tubular epithelium and an improvement in kidney function.
This phase is often characterized by a brisk increase in urine output, and is often referred to as the diuretic phase .
Although the GFR may recover to near-normal levels, there is often residual kidney injury manifested by a decrease in GFR from the baseline, a loss of functional reserve of the kidneys or evidence of tubular dysfunction that may persist for months or years.
