In assessing possible acute kidney transplant rejection, which finding is most indicative?

• A. BUN 56 mg/dL and creatinine 1.9 mg/dL.
• B. Temperature 100.6° F.
• C. Sub therapeutic immunosuppression levels.
• D. Acute pain 6/10.

Answer: (C)

Subtherapeutic immunosuppression levels directly reflect insufficient control of the immune response, which allows the recipient’s T cells to recognize and attack the transplanted kidney. When trough levels of immunosuppressant drugs fall below the target range, the risk of acute rejection rises because the immune system is not adequately suppressed. This makes it the most specific and actionable finding related to imminent or ongoing rejection among the options.

Elevated BUN and creatinine can signal kidney dysfunction but aren’t specific to rejection; they can rise for many reasons such as dehydration, infection, or drug toxicity. A fever is nonspecific and can occur with infection or inflammation, not solely rejection. Pain intensity is not a reliable indicator of rejection either.