1 Acute Kidney Injury: Causes and Pathophysiology Free Online FlashCards

What is acute kidney injury?

Acute kidney injury (AKI) is a rapid decline in kidney function.

What are the three broad categories of AKI?

AKI is commonly grouped as prerenal (reduced kidney perfusion), intrinsic (kidney tissue damage), or postrenal (obstructed urine flow). More than one mechanism can contribute.

What initially causes filtration to fall in prerenal AKI?

In prerenal AKI, insufficient blood flow or effective circulating volume lowers filtration; initially, the kidneys have no structural injury.

How do the kidneys respond to reduced perfusion in prerenal AKI?

The kidneys retain sodium and water to support circulating volume.

Which types of volume loss can trigger prerenal AKI?

Vomiting, diarrhea, bleeding, burns, and excessive diuresis can cause volume loss and reduce kidney perfusion.

How can NSAIDs, ACE inhibitors, and ARBs contribute to prerenal AKI?

NSAIDs can limit compensatory blood flow into the glomerulus; ACE inhibitors and ARBs can reduce pressure within it, especially in susceptible patients.

How can prolonged prerenal AKI progress to intrinsic injury?

Severe or prolonged low perfusion can deprive tubules of oxygen and cause structural injury, turning a prerenal problem into intrinsic AKI.

Which kidney structures can be injured in intrinsic AKI?

Intrinsic AKI can damage the kidney tubules, interstitium, glomeruli, or blood vessels.

What can cause acute tubular injury?

Acute tubular injury may follow prolonged ischemia or nephrotoxin exposure, including aminoglycosides and muscle pigment released during rhabdomyolysis.

Name three non-tubular causes of intrinsic AKI.

Other intrinsic causes include medication-related interstitial inflammation, glomerulonephritis, and vascular disorders.

Why can multiple simultaneous stresses increase AKI risk?

Risk rises when kidney reserve is reduced or several stresses combine, such as severe illness or sepsis with dehydration and potentially nephrotoxic drugs.

How does urinary obstruction reduce filtration in postrenal AKI?

Obstruction raises pressure upstream in the urinary tract; pressure transmitted back toward the kidney opposes filtration and lowers the glomerular filtration rate.