Table 4.

Application of the NIH-FDA BEST (Biomarker, EndpointS, and other Tools) framework to CKDu biomarkers

Biomarker type	Definition	Example of use in CKDu
Diagnostic biomarker	A biomarker used to detect or confirm presence of a disease or condition of interest or to identify individuals with a subtype of the disease.	Community screening in conjunction with standard measures of kidney function to identify subclinical disease
Monitoring/response biomarker	A biomarker measured repeatedly for assessing status of a disease or medical condition or for evidence of exposure to (or effect of) a medical product or an environmental agent.	Serial monitoring in high-risk occupations or geographic regions to identify subclinical injury
Predictive biomarker	A biomarker used to identify individuals who are more likely than similar individuals without the biomarker to experience a favorable or unfavorable effect from exposure to a medical product or an environmental agent.	Preoccupational screening
Prognostic biomarker	A biomarker used to identify likelihood of a clinical event, disease recurrence or progression in patients who have the disease or medical condition of interest.	Predicting risk of progression to kidney failure; selection of individuals for closer clinical monitoring
Safety biomarker	A biomarker measured before or after an exposure to a medical product or an environmental agent to indicate the likelihood, presence, or extent of toxicity as an adverse effect.	Preoccupational screening
Susceptibility/risk biomarker	A biomarker that indicates the potential for developing a disease or medical condition in an individual who does not currently have clinically apparent disease or the medical condition.	Preoccupational screening; community screening to identify subclinical disease

CKDu, chronic kidney disease of uncertain etiology; eGFR, estimated glomerular filtration rate; UCr, urinary creatinine; UKIM-1, urinary kidney injury molecule-1.