During a follow-up visit, which data would best support a diagnosis of acute kidney transplant rejection?

• A. Acute pain rated 6/10.
• B. Blood pressure 178/96 mmHg.
• C. Sub therapeutic immunosuppression levels.
• D. BUN 56 mg/dL and creatinine 1.9 mg/dL.

Answer: (C)

Acute kidney transplant rejection happens when the immune system mounts a response against the donated organ. The clearest data pointing to rejection is evidence of under-immunosuppression: if the trough levels of the immunosuppressant are subtherapeutic, the immune system isn’t adequately suppressed and is more likely to attack the graft. This directly links the lack of sufficient immunosuppression to the risk of, or actual, rejection, guiding clinicians to adjust therapy promptly.

Other findings like pain, high blood pressure, or elevated BUN and creatinine indicate kidney stress or dysfunction but are not specific to rejection. They can occur with dehydration, nephrotoxicity, or other forms of kidney injury and don’t by themselves prove an immune-mediated rejection. Thus, subtherapeutic immunosuppression levels best support the diagnosis and management decision in this context.