Which of the following clients is most likely at risk for developing postrenal renal failure?

The client diagnosed with renal calculi is most likely at risk for developing postrenal renal failure due to the potential for obstruction of urine flow. Renal calculi, or kidney stones, can lead to blockage in the ureters, which impedes the normal outflow of urine from the kidneys. This blockage can result in increased pressure in the renal pelvis, ultimately leading to kidney damage if the obstruction is not relieved. Postrenal failure specifically refers to conditions where urine flow is blocked after it is formed, so the presence of stones that can obstruct the urinary tract puts this client in a higher risk category for such failure.

In contrast, taking NSAIDs for arthritis pain generally contributes to renal issues related to reduced blood flow to the kidneys rather than blockage. Congestive heart failure impacts renal perfusion but does not present a direct obstruction. Recovery from glomerulonephritis may involve risks related to kidney function, yet it does not inherently involve obstruction that characterizes postrenal failure. Thus, the presence of renal calculi stands out as a clear and direct risk factor for developing postrenal renal failure.