Despite the substantial successes of kidney transplantation, this field continues to be hampered by the inability to monitor the intensity of the immunosuppressive regimens. As a result, chronic antibody-mediated rejection (under-immunosuppression), as well as drug-related toxicity, malignancies, and opportunistic infections (over-immunosuppression) continue to be the leading causes of allograft loss.
In addition, counter to all the predictions, the vast improvement in the early acute rejection rate has not resulted in similar improvement in long-term allograft survival. Serum creatinine, the traditional marker to monitor kidney function, is highly unreliable in predicting renal injury of any kind. Protocol kidney biopsies, in addition