<International Circulation>:   How do creatinine levels impact on eGFR?

　　《国际循环》：肌酐水平对eGFR有什么影响吗？
　　Dr Oparil: Creatinine is a protein derived from the breakdown of skeletal muscle and it is filtered by the kidneys. It is used as a marker for kidney failure. If it is elevated， it means that kidney function is poor. We used to use it as the sole marker of determining the level of kidney function but it is very variable coming from skeletal muscle. For example， a 250lb seven foot tall basketball player produces much more creatinine than a 90lb female. So creatinine on its own is not very reliable， so we rely on eGFR which is a lab determined entity. We look at creatinine but it is not precise enough on its own， but it is required as a component of determining eGFR. The four factor MDRD equation includes age， gender， race and serum creatinine. To physically measure GFR， you would have to inject a substance like iothalamate which is filtered by the kidney， but that is an invasive procedure which is useful for research but not done clinically.

　　Dr Oparil: 肌酐是一种来源于骨骼肌降解的蛋白，而且它通过肾脏滤过。我们用肌酐作为肾功能衰竭的标志。如果肌酐水平升高，就意味着肾脏功能的损害。过去我们常常用肌酐来作为评价肾功能水平的唯一标志物，但是它受骨骼肌变异的影响比较大。例如，一名250磅7英尺高的篮球运动员和一个90磅的女性相比，其产生的肌酐要远多于后者。所以单独用肌酐来评价肾功能不是十分可靠，因此我们依靠实验室测量所得的实体eGFR来评价肾功能。我们需要依靠肌酐但是单用这个标志并不非常精确，而要确定eGFR就必须依靠肌酐水平。四因素的MDRD方程包括年龄，性别，种族和血清肌酐水平。为了用物理的方法测量GFR值，我们可能需要注射一种物质比如由肾脏滤过的碘酞酸盐，但是这种侵入性的操作常常用于实验室研究而非临床。