Biomarkers for incident CKD: a new framework for interpreting the literature.

Biomarkers are a useful tool for the investigation of chronic kidney disease (CKD), although the design, analytical tools and outcomes used in many biomarker studies are suboptimal. In part, this situation might reflect a lack of appreciation of the nature of different biomarkers. A particular biomarker could, for example, be implicated in the pathogenesis of CKD because it is a physiological risk factor for declining kidney function, an indicator of impaired kidney function, or a marker of ongoing injury within the kidney. Such risk factors enable us to understand the process of disease and to identify treatment targets. By contrast, risk markers enable us to distinguish persons who will or will not develop CKD, even though the markers themselves are not required to be modifiable by (or directly involved in) the disease process. Accurate prediction of CKD risk will probably require a combination of biomarkers of several types, however. This Review offers a conceptual framework for interpreting the results of studies evaluating biomarkers of declining kidney function and incident CKD.