Which laboratory finding would most strongly indicate possible graft dysfunction in a renal transplant recipient?

• A. BUN 56 mg/dL and creatinine 1.9 mg/dL.
• B. Hemoglobin 9.6 g/dL.
• C. Temperature 100.6° F.
• D. Potassium 4.2 mEq/L.

Answer: (A)

Rising waste products in the blood signal that the transplanted kidney isn’t filtering properly. Creatinine is a direct measure of glomerular filtration rate, so a value of 1.9 mg/dL indicates the graft’s filtration is decreased. BUN at 56 mg/dL further supports reduced renal clearance. When both markers are markedly elevated, it points to graft dysfunction, such as acute rejection, nephrotoxic effects from medications, or ischemic injury to the graft.

Anemia (low hemoglobin) can occur after transplantation for various reasons but doesn’t specifically indicate the transplanted kidney’s function. A fever can accompany inflammation or infection but isn’t a direct sign of graft function. A normal potassium level does not reveal dysfunction, since electrolyte disturbances can be variable and are not as specific to the graft’s filtration status.