单项选择题

A.尿素生成率(Urea Nitrogen Appearance,UNA)
B.蛋白质分解代谢率(Protein Catabolic Rcite,PCR)
C.血尿素氮(Blood Urea Nitrogen,BUN)
D.溶质清除指数(Solute Removal Index,SRI )
E.尿素下降率(Urea Reduction Rale,URR)