Special AnnouncementTesting for Chronic Kidney Disease: A Position Statement From the National Kidney Foundation
Section snippets
CKD Prevalence, Risk Factors, and Outcomes
CKD is common in the United States. In 2000, approximately 398,000 people (0.2%) were treated by dialysis or transplantation for chronic kidney failure, the end stage of CKD.7 By 2030, this number is expected to rise to more than 2 million people.8 The estimated prevalence of earlier stages of CKD in US adults was 20 million (11.7%) in 2000, based on the National Health and Nutrition Examination Survey (NHANES)9; there are not yet projections for future prevalence of CKD. Worldwide prevalence
CKD Definition and Testing
CKD is defined by the presence of kidney damage or glomerular filtration rate (GFR) less than 60 mL/min/1.73 m2 (1.0 mL/s/1.73 m2) for 3 or more months, irrespective of cause (Table 4).5, 6 Markers of kidney damage include abnormalities in the serum or urine, or on imaging studies, and reflect the underlying pathology. Proteinuria is the earliest marker of kidney damage in diabetes, hypertension, and glomerular diseases; thus it is the most common marker of kidney damage in adults.5 GFR is
Proteinuria
Proteinuria refers to increased excretion of any urinary protein, including albumin and other serum proteins, and proteins synthesized by the tubule (Tamm-Horsfall protein) or in the lower urinary tract. Albuminuria refers to increased excretion of albumin only. In this article, we refer to testing for proteinuria as tests for detection of proteinuria, including tests for albumin only. We refer to testing for albuminuria as tests for detection of albumin only.
Healthy individuals usually excrete
Interpretation of CKD Tests
Persistent proteinuria or reduction in GFR to below 60 mL/min/1.73 m2 (1.0 mL/s/1.73 m2) is defined as CKD. The lesser accuracy of current estimating equations at higher levels of GFR may make it difficult to interpret GFR estimates near 60 mL/min/1.73m2 (1.0 mL/s/1.73 m2) in some people. In this range, interpretation of GFR estimates depends on the results of tests for markers of kidney damage and the clinical context (Table 9). Patients with proteinuria have CKD even if GFR estimates are 60
Limitations
There are 3 main limitations to the current testing recommendations. First, there is a variable rate of false-positive tests for both urine protein and estimated GFR, depending upon the population screened. Repeated measurements, with confirmation of persistence of abnormal results over 3 months, will diminish the false-positive rate of urine protein testing. Attention to the clinical setting will facilitate proper interpretation of both urine protein and estimated GFR. Second, there is
Application to Public Health Programs
The strategy of screening for CKD by testing both for markers of kidney damage and for the level of kidney function has now been applied in NHANES and in the National Kidney Foundation’s Kidney Early Evaluation Program (KEEP). NHANES is an ongoing survey of a stratified random sample of the noninstitutionalized US population. Data from more than 25,000 people since 1988 has been critical to demonstrate prevalence of CKD, associations with comorbid conditions, and trends over time.9, 41 In the
Acknowledgements
This paper has been approved as the official position of the National Kidney Foundation by the Scientific Advisory Board and Board of Directors.
Support: Dr Vassalotti is the Chief Medical Officer of the National Kidney Foundation. Dr Stevens is Program Director, Implementation, at the National Kidney Foundation Center for Guideline Development and Implementation at Tufts-New England Medical Center; Dr Levey is Director of that center and Editor-in-Chief of AJKD.
Financial Disclosure: Dr Levey
References (42)
- et al.
CKD: Common, harmful, and treatable—World Kidney Day 2007
Am J Kidney Dis
(2007) - et al.
Definition and classification of chronic kidney disease: A position statement from Kidney Disease: Improving Global Outcomes (KDIGO)
Kidney Int
(2005) - et al.
Prevalence of decreased kidney function in Chinese adults aged 35 to 74 years
Kidney Int
(2005) - et al.
Testing for microalbuminuria in 2002: Barriers to implementing current guidelines
Am J Kidney Dis
(2003) - et al.
World Kidney Day: An idea whose time has come
J Am Soc Nephrol
(2006) - et al.
Chronic kidney disease as a global public health problem: Approaches and initiatives: A Position Statement from KDIGO
Kidney Int
(2007) - et al.
Chronic kidney disease; A public health problem that needs a public health action plan
Prev Chronic Dis
(2006) K/DOQI clinical practice guidelines for chronic kidney disease: Evaluation, classification, and stratificationKidney Disease Outcome Quality Initiative
Am J Kidney Dis
(2002)USRDS 2006 Annual Data Report
(2006)- et al.
Projecting the number of patients with end-stage renal disease in the United States to the year 2015
J Am Soc Nephrol
(2005)