Table 1.

Surrogate biomarkers in kidney transplantation: Surrogate end points shown to correlate with post-transplant outcome

Sample Source/Measurement	Strengths	Weaknesses
Serum
Renal function	Serial measurements; provides insight into current graft function	Often involves surrogates (i.e., serum creatinine) to estimate function
DSA (HLA)	Early marker of antibody injury	Uncommon early post-transplant; no effective treatment
Urine
Proteinuria	Shown to be associated with current/future graft status	Results can be influenced by many factors (infection, recurrent disease, etc.)
Tissue
Graft histology (protocol and biopsy for cause)	Visual evidence of what is happening in the graft	Invasive; costly; variable sampling/interpretation