A nurse is caring for a client who reports to the clinic for laboratory tests. The client has an acute kidney injury caused by acute tubular necrosis and asks why their glomerular filtration rate keeps decreasing. Which of the following pathophysiological changes occurring in the kidney should the nurse explain as the cause of decrease?

Rationale: A. In acute tubular necrosis (ATN), the renal tubular epithelial cells are damaged due to ischemia or exposure to nephrotoxic agents. This cellular injury leads to sloughing and necrosis of tubular cells, which obstructs the tubules and causes backflow of filtrate into the interstitium. As a result, glomerular filtration rate (GFR) decreases because the tubules can no longer effectively reabsorb or secrete substances, and the pressure within the tubules rises, opposing filtration. This is a hallmark of intrarenal acute kidney injury. B. A reduction in renal blood flow is characteristic of prerenal acute kidney injury, not ATN. While ischemia can initially cause ATN, once tubular damage occurs, the ongoing decline in GFR is due to cell injury, not perfusion alone. C. An obstruction causing urine backup refers to postrenal acute kidney injury, not ATN. Postrenal causes include kidney stones or tumors, not tubular necrosis. D. Although inflammatory cells may contribute to kidney damage in some forms of nephritis, inflammation is not the primary cause of GFR decline in acute tubular necrosis. The decrease results primarily from tubular cell death and intratubular obstruction rather than immune-mediated injury.