Final answer:
The correct statement about acute kidney injury is that prerenal oliguria is caused by decreased circulatory volume. This condition leads to decreased urine output due to reduced blood flow to the kidneys, not due to direct kidney tissue damage.
Step-by-step explanation:
The accurate statement about acute kidney injury (AKI) is: C. Prerenal oliguria is caused by decreased circulatory volume. In the context of prerenal causes of AKI, the kidneys themselves are not initially damaged. Instead, a decrease in blood flow to the kidneys due to various conditions (like dehydration, shock, or heart failure) leads to diminished kidney function. This reduced circulatory volume can lead to oliguria, which is a decreased urine output, and should not be confused with parenchymal kidney injury, where the damage is to the tissue of the kidneys themselves.
In prerenal azotemia, the kidney response is to conserve water and sodium to try and increase circulatory volume, countering the suggestion that prerenal azotemia increases sodium excretion. Instead, there's a reduction in sodium excretion during prerenal azotemia. The remaining options are incorrect because parenchymal damage does not occur in prerenal oliguria, and prerenal causes do not increase the glomerular filtration rate (GFR) but rather reduce it due to decreased renal perfusion.