Utility and limitations of the use of donor-derived cell-free DNA in kidney transplantation

Table 1 Comparison of advantages and disadvantages between absolute and fractional values

Metric	Advantages	Disadvantages
Absolute value	Not influenced by fluctuations in WBC - derived cfDNA levels	Poor comparability between different experimental platforms
	Not affected by variations in the extent of inflammation in different pathological conditions	Long-term storage of plasma/urine samples, even within the same experimental platform, can also impact results
	Not influenced by recipient cell lysis during blood drawn
Fractional value	Not influenced by total cfDNA degradation and extraction reagents	Prone to fluctuations in WBC levels, such as during rejection detection in infection states
	Strong compatibility between different experimental platforms

WBC: White blood cell; cfDNA: Cell-free DNA.