Explain the major causes of prerenal, postrenal, and intrarenal/intrinsic AKI. Identify the staging for AKI. What do you suspect is the major etiology of Mr. Maddox's AKI?

Question

What will be an ideal response?

Answer 1

Typically, AKI is characterized by a rapid decline in kidney function with an acute elevation of serum creatinine at baseline. There are three types of causes for the kidney dysfunction:
• Prerenal:
- An underlying condition deprives the kidneys of necessary blood flow and decreases the GFR.
- Due to: volume depletion (e.g. via the GI tract or extensive wounds), hypotension/shock, CHF, renal vasoconstriction from medications or hepatorenal issues, and renal artery occlusion from an embolism or thrombosis.
- If blood flow is not restored, necrosis of the cells will occur.
• Intrarenal/Intrinsic:
- Occurs when parts of the kidneys such as the tubule, the interstitium, the glomerulus, or the vasculature are damaged (true kidney problem).
- Underlying conditions that can lead to kidney damage include hypertension, interstitial inflammation from an infection or disease (e.g. lupus, Goodpasture syndrome, acute glomerulonephritis), acute tubular necrosis, acute interstitial nephritis, nephrotoxicity, or intrarenal obstruction.
• Postrenal: Results when crystals, protein deposits, blood clots, or malignant tumor infiltration obstruct urine flow.
• There are typically 4 stages involved with AKI:
- Initiation: when GFR declines
- Extension: when ischemia and inflammatory damage occur
- Maintenance: when GFR is at its lowest level
- Recovery: when epithelial cells regenerate
Mr. Maddox is most likely experiencing AKI due to a deprivation of blood (oxygenation) during recovery from surgery as it was noted that he had a sudden drop of blood pressure. The infection following his CABG ? 3, which may have lead to inflammation and therefore kidney damage, may also have been a contributing factor.