Which finding is most concerning for potential acute rejection requiring urgent evaluation?

• A. Temperature 100.6 F.
• B. Hemoglobin 9.6 g/dL.
• C. Oliguria.
• D. Blood pressure 178/96 mmHg.

Answer: (C)

A sudden drop in urine output is the most time-sensitive sign of acute rejection in a transplanted kidney because it directly reflects a decline in graft function. When the kidney’s filtering ability is acutely compromised by an immune attack, urine production can fall quickly, signaling that the graft may be at risk. This prompts urgent evaluation to determine whether rejection is occurring and to adjust immunosuppressive therapy promptly, with steps such as checking the creatinine trend, imaging, and potentially a biopsy to guide treatment.

Mild fever can occur with many conditions and isn’t specific to graft dysfunction. Anemia has many causes and doesn’t specifically indicate that the transplanted kidney is undergoing rejection. Hypertension can accompany renal problems but doesn’t alone demonstrate an urgent, rejection-related crisis requiring immediate evaluation as clearly as a drop in urine output does.