ATI CBC Level 3 Practice Test

Reduced renal perfusion lowers the glomerular filtration rate without directly injuring kidney tissue. When the kidneys don’t receive enough blood flow, they conserve sodium and water and the filtration drops, causing azotemia that is classified as prerenal. This is why interference with renal perfusion is the correct way to describe prerenal causes. Obstruction of the urinary tract causes postrenal azotemia, not a perfusion problem. Glomerular inflammation is an intrinsic renal issue that damages the filtering units themselves. Acute tubular necrosis is also intrinsic: it involves damage to the tubular cells from ischemia or toxins. Prerenal azotemia, in contrast, centers on decreased blood flow to the kidneys and can, if not corrected, progress to intrinsic injury, but its starting event is reduced perfusion.